IC 9515 

INFORMATION CIRCULAR/2009 

Compendium of Structural Testing Data 

for 20-psi Coal Mine Seals 

Department of Health and Human Services 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health 
 

Information Circular 9515 

Compendium of Structural Testing Data for 

20-psi Coal Mine Seals 

By R. Karl Zipf, Jr., Ph.D., P.E., Eric S. Weiss, Samuel P. Harteis, P.E., 

 and Michael J. Sapko 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health
 

Pittsburgh Research Laboratory 

Pittsburgh, PA 

August 2009 
This document is in the public domain and may be freely copied 

or reprinted. 

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DHHS (NIOSH) Publication No. 2009–151 

August 2009 

SAFER • HEALTHIER • PEOPLETM 
CONTENTS
 

Page 

Abstract............................................................................................................................................1 

Introduction......................................................................................................................................2 

Experimental mine and test procedures ...........................................................................................5 

Lake Lynn experimental mine (LLEM)..................................................................................5 

Explosion tests in the LLEM ..................................................................................................6
 

Hydrostatic chamber tests in the LLEM .................................................................................7 

Instrumentation and data collection.................................................................................................8 

Pressure waves from test explosions.......................................................................................8 

Pressure and displacement measurement locations ................................................................9 

Loading conditions for seal tests...........................................................................................10
 

Boundary conditions for seal tests ........................................................................................11 

Response times, time constants, and frequency responses for sensors used in the LLEM .....11 

Data acquisition system characteristics ................................................................................16 

Quality of pressure-time and displacement-time measurements ..........................................17 

Adequacy of pressure-time and displacement-time measurements for structural analysis .....20 

Comments on smoothing ......................................................................................................21 

General construction details for category 1 through 6 seals..........................................................21 

Category 1 seals: concrete or concretelike materials with internal steel reinforcement 

 and anchorage to rock .......................................................................................................21 

Category 2 seals: pumpable cementitious materials with no steel reinforcement and 

 no hitching ........................................................................................................................27 

Category 3 seals: articulated structures – solid and hollow-core concrete blocks with 

 or without hitching............................................................................................................30 

Category 4 seals: polymer and aggregate materials without hitching..................................38 

Category 5 seals: wood-crib-block seals with or without hitching ......................................40 

Category 6 seals: articulated structures – lightweight blocks with or without hitching.......45 

Structural testing data for 20-psi coal mine seals ..........................................................................49 

Summary and conclusions .............................................................................................................57 

References......................................................................................................................................58 

Appendix.—Detailed summary of seal structure tests and test data..............................................60 

ILLUSTRATIONS 

1. Plan view of the Lake Lynn experimental mine (LLEM)...........................................................5 

2. Plan view of the LLEM showing the multiple-entry area and the seal and stopping

 locations ..................................................................................................................................6 

3. Schematic of the hydrostatic chamber ........................................................................................7 

4. Schematic of pressure and displacement measurement points for typical explosion tests 

in the LLEM............................................................................................................................9 

5. Dimensionless response function for instantaneous unit step input .........................................12 

6. Calculated pressure response for instantaneous 100-psi step input..........................................13 

7. Calculated pressure response for instantaneous 300-psi step input..........................................14 

8. Calculated displacement response for instantaneous 6-in step input (10-ms response time)......15 

9. Calculated displacement response for instantaneous 6-in step input (75-ms response time)......16 
CONTENTS—Continued 

Page 

10. Typical P-t and D-t data for the entire duration of an explosion test in the LLEM................17 

11. Expanded time-scale view of P-t data from two separate pressure transducers .....................18 

12. Expanded time-scale view of P-t data from the same pressure transducer recorded with 

 separate data acquisition systems operating at 1,500 and 5,000 samples per second.........18 

13. Expanded time-scale view of D-t data from the same displacement transducer recorded 

 with separate data acquisition systems operating at 1,500 and 5,000 samples per 

second .................................................................................................................................19 

14. Computed D-t responses for hypothetical structure using P-t curves in Figure 12 as 

input for structural analysis.................................................................................................20 

15. Front-, plan-, and side-view drawings of category 1A structure: Insteel 3-D seal from

 Precision Mine Repair, Inc. ................................................................................................22 

16. Detailed plan-view drawing of category 1A structure: Insteel 3-D seal from Precision 

Mine Repair, Inc. ................................................................................................................23 

17. Closeup of a rear Insteel panel with Stayform backing and the horizontal #3 steel 

 reinforcement bars ..............................................................................................................23 

18. Insteel 3-D seal under construction showing the rear Insteel panel with stayform backing, 

 one plane of vertical #8 steel reinforcement bars and anchors, the horizontal #8 steel 

 reinforcement bar anchors, and the horizontal #3 steel reinforcement bars .......................24 

19. Insteel 3-D seal under construction with the addition of the front Insteel panel and the 

 front plane of vertical #8 steel reinforcement bars .............................................................25 

20. Front-, plan-, and side-view drawings of category 1B structure: Meshblock seal from

 R. G. Johnson Co., Inc. .......................................................................................................26 

21. Closeup of Meshblock seal under construction showing the Meshblocks and the vertical 

 #8 steel reinforcement bars and anchors.............................................................................27 

22. Meshblock seal under construction showing the lower Meshblocks, the vertical #8 steel 

 reinforcement bars and anchors, and placement of shotcrete .............................................27 

23. Front-, plan-, and side-view drawings of category 2 structure made from pumpable 

 cementitious materials with no steel reinforcement and no hitching..................................28 

24. Formwork for a typical pumpable seal showing the vertical posts, the horizontal boards, 

 and the brattice liner (partially removed)............................................................................29 

25. Inside the formwork of a typical pumpable seal showing the brattice liner and the 

 cementitious filling material ...............................................................................................29 

26. Front-, plan-, and side-view drawings of category 3A structure: standard solid-concreteblock seal with simulated hitching......................................................................................31 

27. Solid-concrete-block seal under construction showing the center pilaster and the fully 

 mortared joints on all sides .................................................................................................32 

28. In background, top of a solid-concrete-block seal showing small cut blocks and mortar 

 filling at the seal top............................................................................................................32 

29. Completed solid-concrete-block seal without a center pilaster showing the angle iron 

hitch on the ribs and floor only...........................................................................................33 

30. Front-, plan-, and side-view drawings of category 3B structure: solid-concrete-block seal

 with Packsetter bags............................................................................................................34 
CONTENTS—Continued 

Page 

31. Tongue-and-groove, solid-concrete-block seal with center pilaster using pressurized 

 Packsetter grout bags in lieu of hitching around the seal perimeter ...................................35 

32. Front-, plan-, and side-view drawings of category 3C structure: solid- or hollow-core 

concrete block ventilation stoppings...................................................................................36 

33. Dry-stacked concrete block stopping showing wedges used to fit the stopping to ribs and 

 small cut blocks and a wood plank at the top .....................................................................37 

34. Dry-stacked concrete block stopping showing application of an approved sealant to the 

surface.................................................................................................................................37 

35. Front-, plan-, and side-view drawings of category 4 structure: polymer and aggregate seal ....38 

36. Polymer and aggregate seal from MICON showing the rear dry-stacked, hollow-core 

 concrete block wall, the partially completed front wall, a polymer coating on the 

 inside surface of the form walls, and an approved sealant on the outside surface of the 

 form wall.............................................................................................................................39 

37. Polymer and aggregate seal from MICON showing the rear and front form wall, the 

 polymer coating on the inner surfaces of the form walls, and the polyurethane foam

 and aggregate mixture filling the inner core of the seal......................................................40 

38. Front-, plan-, and side-view drawings of category 5A structure: wood-crib-block seal 

 with plywood facing and simulated hitching......................................................................41 

39. Closeup of a hitched wood-crib-block seal showing the layer of rock dust placed 

 between each layer of wood crib blocks.............................................................................41 

40. Construction of a hitched wood-crib-block seal without plywood facing showing the 

 wood crib blocks separated by a rock dust layer, the angle iron hitching around the 

 ribs and floor only, and the final coating with an approved sealant ...................................42 

41. Front-, plan-, and side-view drawings of category 5B structure: wood-crib-block seal 

with Packsetter bags............................................................................................................43 

42. Construction of a wood-crib-block seal with pressurized Packsetter grout bags in lieu of 

 hitching showing the application of glue between all wood-crib-block surfaces...............44 

43. Construction of a wood-crib-block seal with pressurized Packsetter grout bags in lieu of 

 hitching showing the glued wood crib blocks and the grout bags used along the roof 

and ribs................................................................................................................................44 

44. Front-, plan-, and side-view drawings of category 6A structure: lightweight block seal, 

24 in thick with hitching .....................................................................................................46 

45. Construction of a 24-in-thick Omega block seal with hitching and a center pilaster.............46 

46. Construction of an Omega block seal showing the wood board and wedges used to secure

 the seal at the roof...............................................................................................................47 

47. Completed 24-in-thick Omega block seal showing the angle iron hitch along the ribs 

 and floor and the outer surface coated with an approved sealant .......................................47 

48. Front-, plan-, and side-view drawings of category 6B structure: lightweight block seal, 

40 in thick without hitching ................................................................................................48 

49. Construction of a 40-in-thick Omega block seal without hitching and no center pilaster......49 
CONTENTS—Continued 

Page 

A-1. Category 1A - structure #1 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #419.............................................................80 

A-2. Category 1A - structure #2 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #419.............................................................80 

A-3. Category 1A - structure #3 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #419.............................................................81 

A-4. Category 1A - structure #4 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #420.............................................................81 

A-5. Category 1A - structure #5 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #420.............................................................82 

A-6. Category 1A - structure #6 - test 1 - static, nonuniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - LLEM test #420.............................................................82 

A-7. Category 1A - structure #7 - test 1 - static, uniform loading; Insteel 3-D seal - 

 shotcrete with reinforcement - PR-1...............................................................................83 

A-8. Category 1B - structure #1 - tests 1 to 4 - static, nonuniform loading; Meshblock seal - 

 shotcrete with reinforcement - LLEM tests #347–350 ...................................................83 

A-9. Category 1B - structure #1 - tests 5 to 8 - static, nonuniform loading; Meshblock seal - 

 shotcrete with reinforcement - LLEM tests #351–358 ...................................................84 

A-10. Category 1B - structure #1 - tests 9 to 12 - static, nonuniform loading; Meshblock seal - 

 shotcrete with reinforcement - LLEM tests #359–362 ...................................................84 

A-11. Category 1B - structure #1 - tests 13 to 16 - static, nonuniform loading; Meshblock 

 seal - shotcrete with reinforcement - LLEM tests #363–366..........................................85 

A-12. Category 1B - structure #2 - tests 1 to 3 - static, nonuniform loading; Meshblock seal - 

 shotcrete with reinforcement - LLEM tests #347–349 ...................................................85 

A-13. Category 1B - structure #2 - tests 4 and 5 - static, nonuniform loading; Meshblock 

 seal - shotcrete with reinforcement - LLEM tests #350–351..........................................86 

A-14. Category 1B - structure #3 - tests 1 to 3 - static, nonuniform loading; Meshblock 

 seal - shotcrete with reinforcement - LLEM tests #347–349..........................................86 

A-15. Category 1B - structure #4 - tests 1 and 2 - static, nonuniform loading; Meshblock 

 seal - shotcrete with reinforcement - LLEM tests #347–348..........................................87 

A-16. Category 1B - structure #5 - tests 1 and 2. Meshblock seal - shotcrete with reinforce- 

 ment - LLEM tests #347–348 .........................................................................................87 

A-17. Category 1B - structure #6 - tests 1 and 2 - static, nonuniform loading; Meshblock seal - 

 shotcrete with reinforcement - LLEM tests #350–351 ...................................................88 

A-18. Category 2A - structure #1 - test 1 - reflected, uniform loading; pumpable 48 in - 

LLEM test #508 ..............................................................................................................88 

A-19. Category 2A - structure #1 - test 2 - reflected, uniform loading; pumpable 48 in - 

LLEM test #509 ..............................................................................................................89 

A-20. Category 2A - structure #2 - test 1 - static, uniform loading; pumpable 48 in - test 

C3-44E ............................................................................................................................89 

A-21. Category 2A - structure #3 - test 1 - static, uniform loading; pumpable 48 in - test 

C7-64W...........................................................................................................................90 
CONTENTS—Continued 

Page 

A-22. Category 2A - structure #3 - test 2 - static, uniform loading; pumpable 48 in - test 

C7-68W...........................................................................................................................90 

A-23. Category 2A - structure #3 - test 3 - static, uniform loading; pumpable 48 in - test 

C7-70W...........................................................................................................................91 

A-24. Category 2A - structure # 4 - test 1 - static, uniform loading; pumpable 48 in - test 

L2-51E ............................................................................................................................91 

A-25. Category 2B - structure #1 - tests 1 and 2 - static, nonuniform loading; pumpable 36 in - 

LLEM tests #354–355.....................................................................................................92 

A-26. Category 2C - structure #1 - tests 1 and 2 - static, nonuniform loading; pumpable 24 in - 

LLEM tests #354–355.....................................................................................................92 

A-27. Category 2C - structure #2 - tests 1 and 2 - static, nonuniform loading; pumpable 24 in - 

LLEM tests #354–355.....................................................................................................93 

A-28. Category 2C - structure #3 - tests 1 and 2 - static, nonuniform loading; pumpable 24 in - 

LLEM tests #354–355.....................................................................................................93 

A-29. Category 2C - structure #4 - test 1 - static, nonuniform loading; pumpable 24 in - 

LLEM test #403 ..............................................................................................................94 

A-30. Category 2C - structure #4 - test 2 - static, nonuniform loading; pumpable 24 in - 

LLEM test #404 ..............................................................................................................94 

A-31. Category 2C - structure #4 - test 3 - static, nonuniform loading; pumpable 24 in - 

LLEM test #405 ..............................................................................................................95 

A-32. Category 2C - structure #4 - test 4 - static, nonuniform loading; pumpable 24 in - 

LLEM test #406 ..............................................................................................................95 

A-33. Category 3A - structure #1 - test 1 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #403............................................................................96 

A-34. Category 3A - structure #1 - test 2 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #404............................................................................96 

A-35. Category 3A - structure #1 - test 3 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #405............................................................................97 

A-36. Category 3A - structure #1 - test 4 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #406............................................................................97 

A-37. Category 3A - structure #2 - tests 1 to 6 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM tests #500–505 ..................................................................98 

A-38. Category 3A - structure #2 - tests 7 to 10 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM tests #506–509 ..................................................................98 

A-39. Category 3A - structure #3 - test 1 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #506............................................................................99 

A-40. Category 3A - structure #3 - test 2 - static, nonuniform loading; standard solid- 

 concrete-block seal - LLEM test #507............................................................................99 

A-41. Category 3A - structure #4 - test 1 - static, uniform loading; standard solid-concreteblock seal - test C1-5E ..................................................................................................100 

A-42. Category 3A - structure #4 - test 2 - static, uniform loading; standard solid-concreteblock seal - test C1-8E ..................................................................................................100 
CONTENTS—Continued 

Page 

A-43. Category 3A - structure #4 - test 3 - static, uniform loading; standard solid-concreteblock seal - test C1-9E ..................................................................................................101 

A-44. Category 3A - structure #4 - test 4 - static, uniform loading; standard solid-concreteblock seal - test C1-10E ................................................................................................101 

A-45. Category 3A - structure #4 - test 5 - static, uniform loading; standard solid-concreteblock seal - test C1-11E ................................................................................................102 

A-46. Category 3A - structure #5 - test 1 - static, uniform loading; standard solid-concreteblock seal - test C6-60W...............................................................................................102 

A-47. Category 3A - structure #5 - test 2 - static, uniform loading; standard solid-concreteblock seal - test C6-62E ................................................................................................103 

A-48. Category 3A - structure #6 - test 1 - static, uniform loading; standard solid-concreteblock seal - test L1-37E ................................................................................................103 

A-49. Category 3A - structure #7 - test 1 - static, uniform loading; standard solid-concreteblock seal - test SRCM 1 ..............................................................................................104 

A-50. Category 3B - structure #1 - test 1 - static, nonuniform loading; solid-concrete-block 

 seal with Packsetter bags - LLEM test #365.................................................................104 

A-51. Category 3B - structure #2 - tests 1 and 2 - static, nonuniform loading; solid-concrete- 

 block seal with Packsetter bags - LLEM tests #365–366 .............................................105 

A-52. Category 3B - structure #3 - tests 1 and 2 - static, nonuniform loading; solid-concrete- 

 block seal with Packsetter bags - LLEM tests #365–366 .............................................105 

A-53. Category 3C - structure #1 - test 1 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #427...............................................................106 

A-54. Category 3C - structure #1 - test 2 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #428...............................................................106 

A-55. Category 3C - structure #2 - test 1 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #427...............................................................107 

A-56. Category 3C - structure #2 - test 2 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #428...............................................................107 

A-57. Category 3C - structure #3 - test 1 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #427...............................................................108 

A-58. Category 3C - structure #3 - test 2 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #428...............................................................108 

A-59. Category 3C - structure #3 - test 3 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #429...............................................................109 

A-60. Category 3C - structure #3 - test 4 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #430...............................................................109 

A-61. Category 3C - structure #3 - test 5 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #432...............................................................110 

A-62. Category 3C - structure #3 - test 6 - static, nonuniform loading; hollow-core concrete- 

 block ventilation stopping - LLEM test #433...............................................................110 

A-63. Category 3C - structure #4 - test 1 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #427...............................................................111 
CONTENTS—Continued 

Page 

A-64. Category 3C - structure #4 - test 2 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #428...............................................................111 

A-65. Category 3C - structure #4 - test 3 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #429...............................................................112 

A-66. Category 3C - structure #4 - test 4 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #430...............................................................112 

A-67. Category 3C - structure #4 - test 5 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #432...............................................................113 

A-68. Category 3C - structure #4 - test 6 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #433...............................................................113 

A-69. Category 3C - structure #4 - test 7 - static, nonuniform load; hollow-core concrete- 

 block ventilation stopping - LLEM test #434...............................................................114 

A-70. Category 3C - structure #5 - test 1 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #457.........................................................................114 

A-71. Category 3C - structure #5 - test 2 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #458.........................................................................115 

A-72. Category 3C - structure #5 - test 3 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #459.........................................................................115 

A-73. Category 3C - structure #5 - test 4 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #460.........................................................................116 

A-74. Category 3C - structure #5 - test 5 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #461.........................................................................116 

A-75. Category 3C - structure #5 - test 6 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #462.........................................................................117 

A-76. Category 3C - structure #6 - test 1 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #457.........................................................................117 

A-77. Category 3C - structure #6 - test 2 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #458.........................................................................118 

A-78. Category 3C - structure #6 - test 3 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #459.........................................................................118 

A-79. Category 3C - structure #6 - test 4 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #460.........................................................................119 

A-80. Category 3C - structure #6 - test 5 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #461.........................................................................119 

A-81. Category 3C - structure #6 - test 6 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #462.........................................................................120 

A-82. Category 3C - structure #6 - test 7 - static, nonuniform loading; solid-concrete-block 

ventilation stopping - LLEM test #463.........................................................................120 

A-83. Category 3C - structure #7 - tests 1 to 3 - static, nonuniform loading; solid-concrete- 

 block ventilation stopping - LLEM tests #510–512 .....................................................121 

A-84. Category 3C - structure #7 - tests 4 to 6 - static, nonuniform loading; solid-concrete- 

 block ventilation stopping - LLEM tests #513–515 .....................................................121 
CONTENTS—Continued 

Page 

A-85. Category 3C - structure #7 - tests 7 to 10 - static, nonuniform loading; solid- 

 concrete-block ventilation stopping - LLEM tests #516–519.....................................122 

A-86. Category 3C - structure #8 - test 1 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #510.......................................................................122 

A-87. Category 3C - structure #8 - test 2 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #511.......................................................................123 

A-88. Category 3C - structure #8 - test 3 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #512.......................................................................123 

A-89. Category 3C - structure #8 - test 4 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #513.......................................................................124 

A-90. Category 3C - structure #8 - test 5 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #514.......................................................................124 

A-91. Category 3C - structure #8 - test 6 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #515.......................................................................125 

A-92. Category 3C - structure #8 - test 7 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #516.......................................................................125 

A-93. Category 3C - structure #8 - test 8 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #517.......................................................................126 

A-94. Category 3C - structure #8 - test 9 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #518.......................................................................126 

 A-95. Category 3C - structure #8 - test 10 - static, nonuniform loading; solid-concrete-block 

 ventilation stopping - LLEM test #519.......................................................................127 

A-96. Category 4 - structure #1 - test 1 - static, uniform loading; polymer and aggregate 

seal - test C8................................................................................................................127 

A-97. Category 4 - structure #1 - test 1 - static, uniform loading; polymer and aggregate 

seal - test C8................................................................................................................128 

A-98. Category 4 - structure #1 - test 1 - static, uniform loading; polymer and aggregate 

seal - test C8................................................................................................................128 

A-99. Category 4 - structure #1 - test 1 - static, uniform loading; polymer and aggregate 

seal - test C8................................................................................................................129 

A-100. Category 5B - structure #1 - test 1 - static, nonuniform loading; wood-crib-block seal 

 with Packsetter bags - LLEM test #396......................................................................129
 

A-101. Category 5B - structure #1 - test 2 - static, nonuniform loading; wood-crib-block seal 

 with Packsetter bags - LLEM test #399......................................................................130
 

A-102. Category 6A - structure #3 - test 1 - static, nonuniform loading; lightweight blocks - 

 24 in with hitching - LLEM test #508 ........................................................................130 

A-103. Category 6A - structure #3 - test 2 - static, nonuniform loading; lightweight blocks - 

 24 in with hitching - LLEM test #509 ........................................................................131 

A-104. Category 6A - structure #2 - test 1 - static, uniform loading; lightweight blocks - 

24 in with hitching - test 4-48.....................................................................................131 

A-105. Category 6B - structure #1 - test 1 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #403...........................................................................132 
CONTENTS—Continued 

Page 

A-106. Category 6B - structure #1 - test 2 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #404...........................................................................132 

A-107. Category 6B - structure #1 - test 3 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #405...........................................................................133 

A-108. Category 6B - structure #1 - test 4 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #406...........................................................................133 

A-109. Category 6B - structure #2 - test 1 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #501...........................................................................134 

A-110. Category 6B - structure #2 - test 2 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #502...........................................................................134 

A-111. Category 6B - structure #2 - test 3 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #503...........................................................................135 

A-112. Category 6B - structure #2 - test 4 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #504...........................................................................135 

A-113. Category 6B - structure #2 - test 5 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #505...........................................................................136 

A-114. Category 6B - structure #2 - test 6 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #506...........................................................................136 

A-115. Category 6B - structure #2 - test 7 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #507...........................................................................137 

A-116. Category 6B - structure #2 - tests 8 and 9 - static, nonuniform loading; lightweight 

blocks - 40 in, no hitching - LLEM tests #508–509 ...................................................137 

A-117. Category 6B - structure #3 - test 1 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #501...........................................................................138 

A-118. Category 6B - structure #3 - test 2 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #502...........................................................................138 

A-119. Category 6B - structure #4 - test 1 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #503...........................................................................139 

A-120. Category 6B - structure #4 - test 2 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #504...........................................................................139 

A-121. Category 6B - structure #4 - test 3 - static, nonuniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #505...........................................................................140 

A-122. Category 6B - structure #5 - test 1 - reflected, uniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #502...........................................................................140 

A-123. Category 6B - structure #6 - test 1 - reflected, uniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #503...........................................................................141 

A-124. Category 6B - structure #6 - test 2 - reflected, uniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #504...........................................................................141 

A-125. Category 6B - structure #6 - test 3 - reflected, uniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #505...........................................................................142 

A-126. Category 6B - structure #7 - test 1 - reflected, uniform loading; lightweight blocks - 

40 in, no hitching - LLEM test #506...........................................................................142 

A-127. Category 6B - structure #8 - test 1 - static, uniform loading; lightweight blocks - 

 40 in, no hitching - test C5-53E..................................................................................143 
CONTENTS—Continued 

TABLES 

Page 

1. Summary of seal types and structural testing data for 20-psi seal designs.............................3 

2. Total number and distribution of different seal categories as of November 2006..................4 

3. Response time, time constant, and frequency response for various pressure transducers 

used to record P-t data during LLEM tests .......................................................................13

 4. Response time, time constant, and frequency response for displacement transducers used 

 to record D-t data during LLEM tests...............................................................................15 

5. Summary of category 1 seal structures: concrete with steel reinforcement .........................51 

6. Summary of category 2 seal structures: pumpable cementitious materials..........................52 

7. Summary of category 3 seal structures: articulated structures .............................................54 

8. Summary of category 4 seal structures: polymer and aggregate structures .........................54 

9. Summary of category 5 seal structures: wood-crib-block structures ...................................55 

10. Summary of category 6 seal structures: lightweight block structures..................................56 

A-1. Detailed summary of seal structure tests ..............................................................................60 
 

 

ACRONYMS AND ABBREVIATIONS USED IN THIS REPORT 

ASTM American Society for Testing and Materials 

CFR Code of Federal Regulations 

D-t displacement-time 

KS Kinetic Systems 

LLEM Lake Lynn Experimental Mine 

LVDT linear variable displacement transducer 

MSHA Mine Safety and Health Administration 

NI National Instruments Corp. 

NIOSH National Institute for Occupational Safety and Health 

P-t pressure-time 

RMR Rock Mass Rating 

SRCM Safety Research Coal Mine 

WAC Wall Analysis Code 

X crosscut (e.g., “X-1” stands for “crosscut 1”) 

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

ft foot 

 ft2 

 square foot 

ft/s foot per second 

gal gallon 

hr hour 

 Hz hertz

 in inch 

lb pound 

 lb/ft3  pound per cubic foot 

m meter 

 min minute

 ms millisecond

 pcf pound per cubic foot 

psi pound-force per square inch 

 psig pound-force per square inch gauge 

sec second 

t ton 

 

 

COMPENDIUM OF STRUCTURAL TESTING DATA 

FOR 20-psi COAL MINE SEALS 

By R. Karl Zipf, Jr., Ph.D., P.E.,1 Eric S. Weiss,2 Samuel P. Harteis, P.E.,3 and Michael J. Sapko4 

1

Senior Research Mining Engineer, Pittsburgh Research Laboratory, National Institute for Occupational Safety and 

Health, Pittsburgh, PA. 2

Team Leader (Senior Research Mining Engineer), Lake Lynn Laboratory Section, Pittsburgh Research Laboratory, 

National Institute for Occupational Safety and Health, Pittsburgh, PA. 3

Research Mining Engineer, Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, 

Pittsburgh, PA. 4

Principal Research Physical Scientist (retired), Pittsburgh Research Laboratory, National Institute for Occupational 

Safety and Health, Pittsburgh, PA. 

ABSTRACT 

This report presents nearly all structural data available from explosion tests of 20-psi mine 

ventilation seals and concrete-block ventilation stoppings that were conducted by the National Institute 

for Occupational Safety and Health during 1997–2008. Although the seals tested were designed to 

meet the former federal 20-psi pressure design standard, the structural information contained herein on 

these seal tests will facilitate the analysis and design of coal mine seals that meet the new explosion 

pressure design criteria of 50 and 120 psi as set forth in the Mine Safety and Health Administration 

(MSHA)’s final rule on “Sealing of Abandoned Areas.” 

The seal testing data are organized into six broad categories of seal structures based on the 

materials used and the construction method for those 20-psi seals: 

1.	 Concretelike materials with steel reinforcement and reinforcement bar anchorage to rock 

2.	 Pumpable cementitious materials of varying compressive strengths with no steel 

reinforcement and no hitching 

3.	 Articulated structures such as solid-concrete-block seals and ventilation stoppings made of 

solid and hollow-core concrete blocks 

4.	 Polymer and aggregate materials without hitching 

5.	 Wood-crib-block seals with or without hitching 

6.	 Articulated structures such as lightweight blocks with or without hitching 

This summary contains data on 52 different structures in the above categories—44 seals and 

8 ventilation stoppings. The structural data sets include the applied loading on the tested seal represented by a pressure-time curve and, when available, the measured seal response represented by a 

displacement-time curve. The structural data sets enable the calibration and verification of numerical 

models of seal behavior at the 20-psi level, which may then facilitate future structural analyses of seal 

designs for the new 50- and 120-psi explosion pressure design criteria. 
2 

INTRODUCTION 

Seals are barriers constructed in underground coal mines throughout the United States to isolate 

abandoned mining areas from the active workings. Prior to the Sago Mine disaster in 2006, federal 

regulations required seals to withstand a 20-psi explosion pressure. On April 18, 2008, the Mine Safety 

and Health Administration (MSHA) issued “Sealing of Abandoned Areas; Final Rule,” which includes 

requirements for seal strength, design, and construction of seals [73 Fed. Reg.5

 5

Federal Register. See Fed. Reg. in references. 

21182 (2008)]. In the 

final rule [30 CFR6

 6

Code of Federal Regulations. See CFR in references. 

75.335(a)], seals must: 

(1) Withstand 50 psi if the sealed area is monitored and maintained inert; 

(2) Withstand 120 psi if the sealed area is not monitored; or 

(3) Withstand greater than 120 psi if the area is not monitored and certain conditions exist that 

might lead to higher explosion pressure. 

30 CFR 75.335(b)(1) specifies the content of an engineering design application for seals. The design 

application must address the pressure-time (P-t) curve, engineering design and analysis, material 

properties, and other pertinent factors. To facilitate the analysis and design of seal structures that meet 

the new explosion pressure criterion, this report presents all structural data available from explosion 

tests conducted by NIOSH during 1997–2008 on seals designed to meet the former 20-psi pressure 

design standard. 

This report organizes and presents the applied loading or P-t curves and, when available, the 

measured displacement-time (D-t) curves for 44 different seal structures tested prior to 2006 when the 

former 20-psi explosion pressure design criterion applied to mine seals. Also included in this data set 

are the applied loading P-t curves and response D-t curves for eight different ventilation stoppings 

constructed with solid or hollow-core concrete blocks. These structural test results against the stoppings are included as supplemental information pertinent to the design of seals that incorporate concrete blocks in some capacity. 

Table 1 summarizes the testing program for seals designed to meet the former 20-psi pressure 

design standard for seals as conducted by the National Institute for Occupational Safety and Health 

(NIOSH) during 1997–2008. The program included tests on six broad categories of seal structures 

organized by the main seal construction material used and the construction method. 

Category 1 includes seals made of concrete or concretelike materials such as shotcrete or 

gunite with internal steel reinforcement and anchorage to surrounding rock via additional steel 

reinforcement bars. Seals in this category are the Insteel 3-D seal (Precision Mine Repair, Inc., 

Ridgway, IL) and the Meshblock seal (Tecrete Industries Pty. Ltd., New South Wales, Australia, and 

R. G. Johnson Co., Inc., Washington, PA). 

Category 2 includes the so-called pumpable seals constructed with different thicknesses of 

pumpable cementitious material depending on its compressive strength. Category 2 seals do not 

contain internal steel reinforcement and are not hitched7

 7

 “Hitching” a seal involves constructing a foundation for the seal, usually by excavation or trenching into competent 

floor rock and rib coal. 

 to the surrounding rock except through 

friction between the seal material and the rock. Manufacturers of seals in this category include Minova 

(Georgetown, KY), HeiTech Corp. (Cedar Bluff, VA, and Morgantown, WV), and R. G. Johnson Co., 

Inc. (Washington, PA). 

 
Table 1.—Summary of seal types and structural testing data for 20-psi seal designs 

Structure type 

Total No. of 

structures 

tested 

No. of 

structures 

tested with 

multiple 

loads 

No. of 

structures 

tested to 

failure 

No. of tests 

with P-t

data only

No. of tests 

with both

P-t and D-t

data

CATEGORY 1: Concrete or concretelike materials with internal steel reinforcement and anchorage to rock 

1A. Insteel 3-D seal 7 0 0 0 7 

1B. Meshblock seal 6 6 5 30 0 

CATEGORY 2: Pumpable cementitious materials with no steel reinforcement and no hitching 

2A. Compressive strength: 200 psi, 

 >48 in thick 

2B. Compressive strength: 433 psi, 

 >36 in thick 

2C. Compressive strength: 480–600 psi, 

24–30 in thick 

4 

1 

4 

2 

1 

4 

3 

0 

0 

0 

2 

6 

7 

0 

4 

CATEGORY 3: Articulated structures: solid and hollow-core concrete blocks with or without hitching 

3A. Standard solid-concrete-block seal 

 with hitching 

3B. Solid-concrete-block seal with

 Packsetter Bags and without 

 hitching 

3C. Ventilation stoppings: solid and 

 hollow-core concrete blocks 

7 

 3 

8 

5 

3 

8 

3 

1 

7 

11 

5 

10 

14 

0 

40 

CATEGORY 4: Polymer and aggregate materials without hitching 

4. Polymer and aggregate materials 1 0 1 0 1 

 (11 LVDTs) 

CATEGORY 5: Wood-crib-block seals with or without hitching 

5A. Wood-crib-block seal with hitching 

5B. Wood-crib-block seal with glue and 

 Packsetter Bags 

0 

1 

0 

1 

0 

0 

0 

0 

0 

2 

CATEGORY 6: Articulated structures: lightweight blocks with or without hitching 

6A. Lightweight blocks: 24 in thick 

with hitching 

6B. Lightweight blocks: 40 in thick 

without hitching 

2 

8 

1 

5 

2 

6 

0 

2 

3 

22 

TOTAL 52 36 28 66 100 

Category 3 seals are “articulated” structures made of discrete concrete blocks, either solid or 

hollow-core, which may or may not be hitched to the surrounding rock. Seals in this category are the 

standard solid-concrete-block seal, which required hitching, and the solid-concrete-block seal with 

Packsetter Bags supplied by Strata Mine Services (Strata Products Worldwide, LLC, Marietta, GA), 

which does not require hitching to withstand 20 psi. Also included in this category are ventilation 

stoppings designed to withstand 2-psi overpressure, which are made of solid or hollow-core concrete 

blocks and do not require hitching. 

Category 4 seals are made from polymer mixed with dry, crushed limestone aggregate, ranging 

in size from 0.25 to 1 in, placed between two, dry-stacked, hollow-core or solid-concrete-block 

form walls. This seal does not require hitching. The only example is the MICON 550 seal (MICON, 

Glassport, PA). 

Category 5 seals are made from stacked wood crib blocks nailed together with 4-in-long nails. 

These seals, used where high convergence is expected, require hitching into the surrounding rock. This 

category also includes wood-crib-block seals that were glued together. The use of Packsetter Bags supplied by Strata Mine Services eliminated the requirement for hitching. 

3 
Category 6 seals are made from lightweight Omega blocks (Burrell Mining Products International, Inc., New Kensington, PA), cemented together with an MSHA-approved bonding agent 

called BlocBond, product No. 1225-51, a fiber-reinforced surface bonding cement manufactured by 

Quikrete Co., Atlanta, GA. Lightweight block seals constructed 24 or 32 in thick required hitching, 

whereas lightweight block seals more than 40 in thick did not require hitching. Seals constructed from 

lightweight blocks are no longer permitted, but the data are included herein for completeness. 

This summary of NIOSH seal tests contains data on a total of 52 different structures including 

44 seals and 8 stoppings. As shown in Table 1, many of the structures were subject to multiple loadings, and many of the structures were tested to failure. In some cases, the applied explosion pressure 

severely damaged the structure or collapsed it completely in the first test. In most cases (36 of the 52), 

the structures were subjected to multiple explosion loads. Twenty-eight of the fifty-two structures 

tested were loaded to failure. Finally, as indicated in Table 1, most of the structures considered herein 

have measured response data in the form of a D-t curve from a linear variable displacement transducer 

(LVDT). 

Of the 52 different structures tested (44 seals and 8 stoppings), 41 were tested via explosion 

tests conducted at NIOSH’s Lake Lynn Experimental Mine (LLEM). In addition to the explosion tests, 

11 different structures were tested in one of the hydrostatic chambers located in the LLEM—9 in the 

small hydrostatic test chamber and 2 in the large chamber. Of the 15 tests reported with the small 

hydrostatic chamber in the LLEM, only 5 used water pressure as the loading medium. The other 

10 tests used a confined methane-air or similar gaseous mixture explosion within the hydrostatic 

chamber to develop the test pressure. Both of the tests in the large hydrostatic test chamber used a 

confined gas explosion to develop the test pressure. One test was conducted in an experimental 

chamber in the Safety Research Coal Mine (SRCM) at the NIOSH Pittsburgh Research Laboratory. 

This test used water pressure to develop the applied loading. 

NIOSH researchers also obtained data compiled by MSHA on the approximate number and 

seal type of all of the 20-psi seals in existence as of November 2006. Table 2 presents those numbers 

and the percentage of seals in each category. 

4 

Table 2.—Total number and distribution of different seal categories as of November 2006 

Seal type/ Percent of Description Number category total 

1 Concrete or concretelike materials with internal steel 2,602 20 

reinforcement and anchorage to rock 

2 Pumpable cementitious material with no steel reinforcement 3,153 24 

and no hitching 

3 Articulated structures: solid and hollow-core concrete blocks 2,692 21 

with or without hitching 

4 Polymer and aggregate materials without hitching 1,208 9 

5 Wood-crib-block seals with or without hitching 190 1 

6 Articulated structures: lightweight blocks with or without 3,210 25 

hitching

TOTAL 13,055 100 
EXPERIMENTAL MINE AND TEST PROCEDURES 

Lake Lynn Experimental Mine (LLEM) 

The structural tests on coal mine seals and stoppings were conducted at the NIOSH Lake Lynn 

Laboratory [Mattes et al. 1983; Triebsch and Sapko 1990]. Lake Lynn is one of the world’s foremost 

mining laboratories for conducting large-scale surface and underground research in mining health and 

safety technology. It is located about 50 miles southeast of Pittsburgh, near Fairchance, Fayette 

County, PA, and occupies a former limestone mine. 

The underground LLEM (Figure 1) is unique in that it can simulate current U.S. coal mine 

geometries for a variety of mining scenarios, including multiple-entry room-and-pillar mining and 

longwall mining. The old limestone mine workings are shown on the left in Figure 1.

Figure 1.—Plan view of the Lake Lynn Experimental Mine (LLEM). 

 Five new drifts 

(horizontal passageways in a mine) were developed to simulate the geometries of typical U.S. coal 

mines. The LLEM has four parallel drifts: A, B, C, and D. Drifts C and D are connected by E-drift, 

a 500-ft-long drift that simulates a longwall face. D-drift is a 1,640-ft-long single entry that can be 

separated from E-drift by an explosion-resistant bulkhead door. Drifts A, B, and C simulate longwall 

gate road entries or room-and-pillar workings. These three drifts are each approximately 1,600 ft long, 

5 
 

with seven crosscuts at the inby end. A second explosion-resistant bulkhead door is used to separate 

the multiple entries from E-drift at the intersection with C-drift. 

Explosion tests can be conducted in the single-entry D-drift; the multiple-entry area of A-, B-, 

and C-drifts; or various other configurations including the longwall E-drift. The entries are about 20 ft 

wide by about 6.5 ft high with cross-sectional areas of 130–140 ft2. The crosscuts are 17–19 ft wide 

and about 7.2 ft high with a cross-sectional area of about 130 ft2. 

From August 1983 (when the first explosion test was conducted) to July 2008, a total of 

527 consecutively numbered explosion tests were conducted in the LLEM. 

Explosion Tests in the LLEM 

6 

Figure 2 shows an expanded view of the test area in the multiple-entry section of the LLEM. 

The faces, or inby (closed) ends, of A-, B-, and C-drifts are on the right in the figure. For most of the 

seal and stopping tests, the explosions were conducted in C-drift and the structures were built in crosscuts 1, 2, and 3 between B- and C-drifts, as shown in Figure 2. The evaluation of one type of seal was 

conducted in A-drift with the seals located in the crosscuts between A- and B-drifts. The evaluations of 

some of the ventilation stoppings were also conducted in A-drift as part of another explosion program 

with the stoppings located in X-68

8

The abbreviation “X” stands for “crosscut” throughout this report, e.g., “X-1” stands for “crosscut 1.” 

 and X-7 between A- and B-drifts and seals located in X-1 through 

X-5. For clarity, the A-drift testing scenarios are not shown in Figure 2. 

Figure 2.—Plan view of the LLEM showing the multiple-entry area and the seal and stopping locations. 

The first crosscut, designated as “#1”, is nearest the dead end of drifts A, B, or C. 

Before each explosion test, a 60-t pneumatically operated, track-mounted, concrete and steel 

bulkhead was positioned near the intersection of C- and E-drifts to contain the explosion pressures 

within the multiple-entry area. The LLEM bulkhead door and some of the other infrastructure were 

designed to withstand explosion overpressures of up to 100 psi. Higher pressures have been recorded 

at areas away from these structures. 
For the LLEM explosion tests, natural gas was injected into the ignition zone. This natural gas 

is composed of ~97%–98% methane, ~1.5% ethane, and small percentages of other higher-order 

hydrocarbons. Sample lines within the ignition zone were used to draw gas samples to an infrared 

analyzer on the surface for measurement of the methane concentration. In addition, samples were 

collected in evacuated test tubes and sent to verify the analyses using gas chromatography. Most of the 

tests used a ~9%–10% methane-air concentration within an ignition zone contained in the C-drift face 

area with a clear plastic diaphragm. A few of the tests used a larger gas ignition zone. A fan with an 

explosion-proof motor housing mixed the natural gas and air prior to ignition. Electrically activated 

matches located either at the face (closed end) or outby the face within the gas ignition zone, depending on the explosion overpressure desired, were used to ignite the methane-air mixtures. In some of the 

tests, shelves of pulverized bituminous coal dust were also suspended in the drifts as a means to 

increase the explosion overpressures. For each of these explosion tests, the gas was ignited and the 

explosion pressure traveled out C-drift. For the explosion tests conducted in A-drift, the length of the 

gas ignition zone was varied to obtain higher total explosion overpressures at the stopping locations, 

i.e., the methane-air concentration was contained within a 50- or 85-ft-long gas ignition zone 

(as measured from the closed end of A-drift) for the different tests. 

Hydrostatic Chamber Tests in the LLEM 

Two hydrostatic chambers located within the high-roof section of the LLEM beyond the mouth 

of D-drift (Figure 1) enable researchers to impart pneumatic, hydrostatic, or explosion pressure loadings on test seals. Figure 3 is a schematic of the chamber design showing the test seal in front of a 

dead-end section of tunnel excavation, the support steel surrounding the seal for simulating hitching, 

and the pressurization system using high-pressure water, compressed air, or some combination of the 

two. Sapko et al. [2005] describe the large and small hydrostatic test chambers in the LLEM in greater 

detail. 

7 

Figure 3.—Schematic of the hydrostatic chamber. 
 

 

INSTRUMENTATION AND DATA COLLECTION 

Pressure Waves From Test Explosions 

Upon ignition with the electric matches, the methane-air mixture in the gas zone begins to burn 

and the flame front accelerates rapidly. In some tests, NIOSH researchers placed water-filled 55-gal 

barrels in the gas zone to create additional turbulence, which accelerates the flame front more rapidly. 

In all seal-related tests, the explosion is characterized as a deflagration as opposed to a detonation, 

since the maximum flame speed never exceeds about 1,100 ft/s, which is the local sound speed for the 

unreacted methane-air mixture. 

The accelerating flame front produces pressure waves that travel at the local sound speed ahead 

of the flame front and are characterized by a static pressure component and a dynamic or velocity component. Both of these pressure components are time-dependent. In the free flow field, the sum of these 

two pressure components is the total pressure, which is also time-dependent. 

Initially, the pressure waves emanating from a methane-air explosion rise from initial static 

pressure to peak static pressure slowly over a period of many tens of milliseconds. The time to go from 

initial to peak static pressure is termed the “rise time.” The leading and lower pressure part of the blast 

wave travels at the local sound speed. However, at higher pressure, the local sound speed increases 

slightly. As the pressure wave propagates, the lagging higher pressure part of the wave, which is 

traveling slightly faster than the leading lower pressure part of the wave, will gain on the leading lower 

pressure edge of the wave. Via this mechanism, the rise time of the pressure wave will decrease and 

the blast wave may develop into a shock wave with instantaneous rise time. 

In practice, the blast waves created during some seal-related explosion tests in the LLEM had 

rise times on the order of 10 ms. Theoretical relationships for shock waves with instantaneous rise 

times apply satisfactorily to blast waves with finite rise times of this magnitude. 

The dynamic pressure pV at the shock front is related to the static overpressure pS by [Glasstone 

and Dolan 1977; Kinney 1962; Landau and Lifshitz 1987; Zucrow and Hoffman 1985]: 







5 













p

2 

S 

7 po + pS 







 pV =
 (1) 2
 

where po = initial pressure. 

For weak shock waves where pS goes to zero, pV also goes to zero; for strong shock waves 

where pS becomes large, pV also becomes large. 

When a shock wave strikes a surface such as a seal head on, reflected overpressure pR on the 

seal is given by [Glasstone and Dolan 1977; Kinney 1962; Landau and Lifshitz 1987; Zucrow and 

Hoffman 1985]: 









7 po + 4 pS 

7 po + pS 







 pR =
 2
 pS (2)
 

where pS = static overpressure, 

and po = initial pressure. 

8 
Equation 2 applies to a nonreactive shock or blast wave in which no chemical reactions are 

occurring when the reflecting surface is struck. For weak shock waves where pS approaches zero, 

the reflected overpressure pR is two times the incoming static overpressure pS. For strong shock waves 

where pS becomes large, the reflected overpressure pR can be up to eight times the incoming static 

overpressure. For example, if the static overpressure is 117 psig, then the reflected overpressure is 

about 595 psig, or about five times the incoming static overpressure. 

Pressure and Displacement Measurement Locations 

NIOSH researchers recorded the P-t history applied to seals using different instrumentation 

arrangements that evolved during the course of the 20-psi seal testing program. Figure 4 shows the 

different pressure measurement locations with respect to the tested seals. In all tests, pressure transducers in the data-gathering panels located on the rib of each drift in the LLEM recorded the static 

pressure of the blast waves. In some tests, supplemental instrument stations located in the middle of the 

test drift contained pressure transducers to record the total pressure of the blast waves in the free field. 

Additional instrument stations located in front of test seals in the crosscuts recorded static pressure of the passing blast waves (Figure 4). Test seals constructed in the crosscuts were recessed from 

the main drift anywhere from 0 to 8 ft. These supplemental instrument stations were placed anywhere 

from 1 to 4 ft in front of these crosscut seals. The number of instrument stations in front of each seal 

also varied from one to three, with instruments located either at the seal centerline, along the sides, or 

in combination. Again, the instrument stations in front of these test seals located in crosscuts generally 

recorded the static pressure of the passing blast wave. However, the measurements could also contain 

some of the dynamic component of the pressure wave as well as reflected pressure from wave impact 

on crosscut ribs facing the direction of wave propagation. 

9 

Figure 4.—Schematic of pressure and displacement measurement points for typical explosion tests in the LLEM. 
Also shown in Figure 4 are instrument stations located directly in front of test seals in the main 

test drift. These instruments, located about 1 ft in front of the test seal, recorded the reflected wave 

overpressure on the test seal. The number of instrument stations varied, and the stations were located 

either at the seal centerline, along the sides, or in combination. 

Figure 4 also shows the location of the LVDT to measure the displacement response of the 

structure. When used during a test, the LVDTs were located at midheight along the seal centerline. 

Loading Conditions for Seal Tests 

NIOSH researchers used four distinct test procedures for conducting tests on 20-psi seals. Each 

procedure subjected the test seal to different loading conditions as follows: 

1.	 Explosion tests on seals in crosscuts loaded seals with the static blast wave overpressure 

that is nonuniform across the tested seal face. 

2.	 Explosion tests on seals in C-drift loaded seals with the reflected blast wave overpressure 

that is assumed uniform across the seal. 

3.	 Hydrostatic chamber tests using water pressure loaded seals with a static pressure that is 

nearly uniform across the seal except for the minor gravity effect. 

4.	 Hydrostatic chamber tests using methane ignition pressure loaded seals with a static overpressure that is assumed uniform across the seal. 

Most of the structural tests on seals described herein are of the first type—explosion tests on 

seals in crosscuts. The test explosion began at the closed end of C-drift, and the blast wave propagated 

down the drift and loaded seals located in crosscuts perpendicular to the direction of the main blast 

wave. That test procedure induced a nonuniform, static pressure that swept across the seal face as the 

pressure wave propagated down the entry. The rise times of the loading are longer than the natural 

period of the seals, so for structural purposes, the loading is considered static. The test seal could also 

experience some of the dynamic pressure component and the effects of turbulence depending on how 

far into the crosscut the test seal is recessed. At this time, these effects are unknown and are assumed 

negligible. 

The blast wave propagates at the local sound speed of about 1,100 ft/s, and since the seal has a 

width of about 20 ft, the blast wave traverses past the seal in about 18 ms. The nonuniform, sweeping 

static pressure across the seal at some point in time is represented approximately by an 18-ms window 

from the P-t curve of the blast wave. The magnitude, duration, and shape of the blast wave varied 

considerably from test to test. Thus, the static pressure on the seal could vary significantly from the 

upstream to downstream edge of the seal. For structural analysis purposes, each test will require 

evaluation to determine the significance of this nonuniform pressure distribution on the seal face. 

Several recent structural tests on seals were of the second type—explosion tests on seals in 

C-drift. The test explosion began at the closed end of C-drift, and the blast wave loaded seals located 

across C-drift. This test procedure induced a reflected blast wave overpressure on the seal face that is 

assumed uniform. 

10 
The hydrostatic chamber tests using either water pressure (type 3 test) or methane ignition pressure (type 4 test) applied a static pressure across the seal face. In both test procedures, the pressure on 

the seal face is assumed uniform. For the water pressure test (type 3), the gravity component of the 

water pressure behind the test seal is assumed negligible. In the case of the methane ignition tests, the 

elapsed time (rise time) to develop the pressure is very long with respect to the natural period of the 

tested seals. Therefore, the loading is considered static for structural analysis. 

Boundary Conditions for Seal Tests 

The roof, rib, and floor rocks in the LLEM are limestone with a compressive strength of about 

24,200 psi and a modulus of elasticity of about 9,600,000 psi, based on laboratory tests conducted by 

Dolinar [2008]. The rock mass in the LLEM using the 1989 version of the Rock Mass Rating (RMR) 

system is a good-quality rock mass, with an RMR ranging from 77 to 79 according to Esterhuizen 

[2008]. Therefore, the foundation conditions for seal structures constructed and tested in the LLEM 

represent best-case circumstances and can be described as “rigid” or “unyielding.” The foundation 

conditions for the seal tests in the LLEM as reported here do not represent typical conditions found in 

underground coal mines where the roof and floor rock and the coal ribs may have lower stiffness and 

strength. 

Response Times, Time Constants, and Frequency Responses for 

Sensors Used in the LLEM 

The response of a sensor to a step input depends on the range of the sensor and the time 

constant or frequency response of the sensor as given by the following relations: 

P
  − t  =
 1− exp   (3) PC  T
  

T = 1 / F	 (4)

where P = magnitude of a step input, 

PC = full-scale range of sensor, 

t = response time of sensor, 

T = time constant of sensor, 

and F = frequency response of sensor. 

Figure 5 shows a plot of Equation 3 in dimensionless form. For an instantaneous unit step input 

(P / PC = 1), an electronic sensor will require about three dimensionless time units to reach 95% of the 

step input. 

11 
0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1 

Dimensionless response - P/Pc 

0 0.5 1 1.5 2 2.5 3 3.5 4

Dimensionless time - t/T
 

Figure 5.—Dimensionless response function for instantaneous unit step input. 

Given the measured response time of a sensor to some fraction of the full-scale range of the 

sensor, the time constant and frequency response of the instrument are derived from Equations 3 and 4 

as follows: 

 P  T
 = t / ln 



1− 

 (5)  PC  

 P  F
 = −
 ln 1−
   /t (6)  PC  

NIOSH researchers used numerous brands of pressure transducers during the 20-psi seal testing 

program, including Patriot (AMETEK APT, Clawson, MI), Viatran (Viatran Corp., Grand Island, NY), 

and Transmetrics (Trans Metrics, Division of United Electric Controls, Watertown, MA). All transducers used a strain-gauge array that is bonded to a flat diaphragm to measure pressure-induced deflections of the diaphragm. The capacity of the pressure transducers ranged from 50 to 300 psi depending 

on requirements of a particular explosion test. Table 3 presents the response time (t) provided by 

Transmetrics, the manufacturer for the pressure transducers used in the most recent explosion tests, and 

the calculated time constant (T) and frequency response (F). In the calculations, it is assumed that the 

response time (t) is measured at 90% of the full-scale range of the sensor, i.e., P / PC = 0.9. 

12 
Table 3.—Response time, time constant, and frequency response for various pressure transducers 

used to record P-t data during LLEM tests 

Full-scale range Measured response time t at Calculated time Calculated frequency 

of sensor (psi) 90% of full-scale (ms) constant T (ms) response F (Hz) 

50 <1.6 0.70 1,439 

100 <1.0 0.43 2,300 

200 <0.7 0.30 3,290 

300 <0.37 0.16 6,220 

The data in Table 3 provide a means to judge whether pressure data measured with a particular 

instrument accurately record the actual phenomena. Figure 6 presents the calculated P-t response function for a 100-psi step input using a 100-psi transducer with a 1.0-ms response time. As indicated by 

Figure 6, the 100-psi transducer subject to a 100-psi step input will develop 95% of its response in 

about 1.4 ms. When subject to a smaller step input, the transducer will respond according to the time 

function shown in Figure 6. Using a 100-psi pressure transducer, which is typical for most of the data 

presented herein, the transducer will record the actual phenomena to within 10% of the actual pressure 

as long as the rise time is more than about 1.4 ms. Therefore, when a data point defined by the 

rise time of the recorded response and the magnitude of the peak pressure lies below the response 

function shown in Figure 6, the transducer will record the phenomena reliably. 

13 

 

Response pressure - psi 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 

Time - ms 

Figure 6.—Calculated pressure response for instantaneous 100-psi step input. Pressure transducer has 

1.0-ms response time to 90% of full-scale and 2,300-Hz frequency response. 
Figure 7 presents the calculated P-t response function for a 300-psi step input using a 300-psi 

transducer with a 0.37-ms response time. As indicated in Figure 7, a 300-psi transducer will develop 

95% of its response in about 0.4 ms. With a 300-psi pressure transducer, which was used in some of 

the more recent, higher-pressure explosion tests in the LLEM, the transducer will record the actual 

phenomena to within 10% of the actual pressure as long as the rise time is more than about 0.4 ms. 

The recorded P-t curve is acceptable if a data point defined by the rise time of the recorded response 

and the magnitude of the peak pressure lies below the response function shown in Figure 7. 

 

0 

50 

100 

150 

200 

250 

300 

Response pressure - psi 

0 0.1 0.2 0.3 0.4 0.5 0.6 

Time - ms 

Figure 7.—Calculated pressure response for instantaneous 300-psi step input. Pressure transducer has 

0.37-ms response time to 90% of full-scale and 6,220-Hz frequency response. 

NIOSH researchers closely examined all of the P-t curves presented in the appendix to this 

report to confirm that the data meet the response time criteria presented by the information in Table 3 

and the response time functions shown in Figures 6 and 7. In general, the initial rise times are much 

greater than 10 ms, which is well within the response capabilities of the pressure transducers used in 

these experiments. A point defined by the measured rise time and the magnitude of the peak pressure 

always lies below the calculated response function, indicating that the data quality is acceptable and 

that the measured pressure data accurately reflect the actual pressure developed during the test. 

NIOSH researchers used LVDTs manufactured by Honeywell Sensotec (Columbus, OH) to 

measure displacement response of a seal at its centerline. Measurement range for these instruments is 

up to 6 in. The frequency response for these instruments as stated by the manufacturer is 300 Hz, 

which applies when the measurement rod of the displacement transducer is coupled directly to the 

structure. As will be discussed later, this method of coupling was generally not done in the D-t test data 

14 
reported herein. Table 4 presents the frequency response provided by the manufacturer and the calculated time constant and response time assumed at 95% of the full-scale range of the sensor, i.e., 

P / PC = 0.95. Figure 8 presents the calculated D-t response to a 6-in step input using a 6-in transducer 

with a 10-ms response time. The measured D-t data will reliably reflect the actual D-t phenomena 

when the rise time up to full-scale exceeds 10 ms. For the few tests presented here where the displacement transducer was coupled directly to the structure, the measured rise times exceed 10 ms and the 

recorded D-t curves are therefore considered reliable. 

15 

Table 4.—Response time, time constant, and frequency response for displacement transducers 

used to record D-t data during LLEM tests 

Full-scale range of Response time t at 95% of Calculated time Frequency response F 

sensor (in) full-scale (ms) constant T (ms) (Hz) 

6 <10 300 3.33 with direct coupling (calculated) (from manufacturer) 

6 <75 40 with nylon filament 25.0 (measured in LLEM) (calculated) coupling 

 

Response displacement - inches 

6 

5 

4 

3 

2 

1 

0 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

Time - ms 

Figure 8.—Calculated displacement response for instantaneous 6-in step input. Displacement transducer 

is coupled directly to the structure and has 10-ms response time to 95% of full-scale and 300-Hz frequency 

response. 
NIOSH researchers also employed another method to couple the displacement transducer to the 

structure using a spring-loaded nylon filament to protect the LVDT from damage during an explosion 

test. NIOSH researchers measured the full-scale response time of the LVDT using this experimental 

arrangement as about 75 ms. Based on this measured response time, the calculated time constant and 

frequency response for the LVDT are shown in Table 4. Figure 9 presents the calculated D-t response 

to a 6-in step input using a 6-in transducer with a 75-ms response time. The measured D-t data will 

reliably reflect the actual D-t phenomena when the rise time up to full-scale exceeds 75 ms. For all of 

the tests presented herein where the displacement transducer was coupled to the structure with a 

spring-loaded nylon filament, the measured rise times exceed 75 ms and the recorded D-t curves are 

therefore considered reliable. 

0 

1 

2 

3 

4 

5 

6 

Response displacement - inches 

0 10 20 30 40 50 60 70 80 90 100 

Time - ms 

Figure 9.—Calculated displacement response for instantaneous 6-in step input. Displacement transducer 

is coupled via nylon filament to the structure and has 75-ms response time to 95% of full-scale and 40-Hz 

frequency response. 

Data Acquisition System Characteristics 

A PC-based data acquisition system by National Instruments Corp. (NI) (Austin, TX) recorded 

data from the various instruments at a sampling rate of 1,500 per second. In recent tests, a data acquisition system by Kinetic Systems (KS) (Boston, MA) also recorded data from the various instruments in 

parallel at a sampling rate of 5,000 per second. For consistency, all data reported here come from the 

NI system operating at 1,500 samples per second. 

16 
Quality of Pressure-Time and Displacement-Time Measurements 

Figure 10 presents the P-t and D-t data for the entire duration of an explosion test in the LLEM. 

Beyond the initial arrival and decay of the first pressure wave, the data exhibit noise spikes and other 

extraneous features caused by a variety of experimental realities. Two questions arise with any experimental data: 

1. Are the data real and representative of the physical phenomena under study? 

2. Are the transducers and data acquisition system adequate to record the phenomena with 

sufficient detail for analysis? 

0 

50 

100 

150 

200 

250 

Pressure - psi 

0 

1 

2 

3 

4 

5 

6 

Displacement - inches 

Pressure_1_NI_System 1500/sec 

Displacement_NI_System 1500/sec 

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 

Time - seconds 

Figure 10.—Typical P-t and D-t data for the entire duration of an explosion test in the LLEM. Note noise 

spikes in data beyond 0.7 sec. 

To answer these questions, Figures 11–12 present a close examination of P-t data from a recent 

LLEM test that generated a reflected (head-on) explosion pressure of about 200 psi; Figure 13 presents 

the D-t data. 

Figure 11 presents P-t curves from two separate pressure transducers located close together 

using an expanded time scale centered near the arrival of the first pressure wave. These transducers 

were located on the upstream side of a seal installed across the explosion entry. The green curve is an 

expanded view of the same P-t curve shown in Figure 10. The NI data acquisition system recorded the 

data at 1,500 samples per second. By inspection, both pressure transducers record similar signals with 

similar peak pressures of about 200 psi and similar rise times to peak pressure of about 3–4 ms. The 

observed pressure rise of 200 psi over a rise time of about 3–4 ms is within the capability of the instrument, as shown in Figure 6. NIOSH researchers conclude that the observed peak pressures and rise 

times represent the pressure waves under study. 

17 
 

0 

50 

100 

150 

200 

250 

Pressure - psi 

Pressure_1_NI_System 1500/sec 

Pressure_2_NI_System 1500/sec 

0.51 0.515 0.52 0.525 0.53 0.535 0.54 

Time - seconds 

Figure 11.—Expanded time-scale view of P-t data from two separate pressure transducers. 

Data are recorded with the NI system at 1,500 samples per second. The green P-t curve is the 

same P-t curve shown in Figure 10. 

 

250 

200 

Pressure - psi 

0 

50 

100 

150 

Pressure_1_NI_System 1500/sec 

Pressure_1_KS_System 5000/sec 

0.51 0.515 0.52 0.525 0.53 0.535 

Time - seconds 

Figure 12.—Expanded time-scale view of P-t data from the same pressure transducer recorded 

with separate data acquisition systems operating at 1,500 and 5,000 samples per second. 

0.54 

18 
Figure 12 presents an expanded view of the same P-t curve shown in Figure 10, but as recorded 

with two separate data acquisition systems operating at 1,500 samples per second (the NI system) and 

5,000 samples per second (the KS system). By inspection, both recording systems captured similar 

signals, although the faster KS system provides more detail. NIOSH researchers conclude that the 

pressure transducers and data acquisition system are adequate to record the P-t curves from these 

explosion tests. 

Figure 13 presents an expanded view of the D-t curve shown in Figure 10 as recorded with two 

separate data acquisition systems operating at 1,500 and 5,000 samples per second. For a displacement 

transducer coupled directly to the structure, the observed displacement of about 5.7 in over a time of 

25 ms is within the capability of the instrument, as shown in Figure 8. NIOSH researchers conclude 

that the displacement transducer and data acquisition system are well matched to record the D-t curves 

from these explosion tests. However, NIOSH researchers note that while the system can measure the 

initial displacement response of the seal structures, it may not measure the later vibratory response of 

the structures because of the technique used to couple the LVDT to the structure. Thus, the displacement data are only reliable up to the initial peak displacement and not beyond that point in time. 

19 

0 

1 

2 

3 

4 

5 

6 

Displacement - inches 

Displacement_NI_System 1500/sec 

Displacement_KS_System 5000/sec 

0.51 0.52 0.53 0.54 0.55 0.56 

Time - seconds 

Figure 13.—Expanded time-scale view of D-t data from the same displacement transducer recorded with 

separate data acquisition systems operating at 1,500 and 5,000 samples per second. 
Adequacy of Pressure-Time and Displacement-Time Measurements 

for Structural Analysis 

A final question about the P-t data concerns its adequacy for reliable structural analysis. As 

demonstrated in the previous sections, the pressure transducers and data acquisition system adequately 

capture pressure data with a rise time of at least 100 psi/ms. Higher-frequency components may exist 

in the P-t data that may not be captured adequately. The question arises as to whether these higherfrequency components are important in structural analysis of seals. NIOSH researchers performed a 

simple structural analysis aimed at discerning the possible importance of these higher-frequency 

P-t components. 

For this structural analysis, NIOSH researchers used the Wall Analysis Code (WAC) from the 

U.S. Army Corps of Engineers [Slawson 1995]. WAC is a single-degree-of-freedom structural dynamics model that solves the equation of motion to determine the D-t history at midheight of a wall given 

some P-t curve applied to the wall. The analysis considered a simply supported, 2-ft-thick concrete 

wall. Figure 12 shows the P-t curves considered in the analysis, which were measured with the NI and 

KS data acquisition systems at sampling rates of 1,500 and 5,000 samples per second, respectively. 

Presumably, the data set collected with the KS system contains more of the higher-frequency components of the P-t curve. 

Figure 14 shows the computed D-t responses from these two different P-t curves. The different 

responses are purposely offset in time for clarity. As seen by inspection, no significant difference 

exists between the two computed D-t responses. NIOSH researchers conclude that the P-t data collected by the NI system at 1,500 samples per second are adequate for structural analysis of seals under 

the conditions of the explosion tests conducted in the LLEM for evaluating 20-psi seals. 

20 

0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

Displacement - inches 

WAC calculated displacement - 1500 sample / second data 

WAC calculated displacement - 5000 sample / second data 

0 5 10 15 20 25 30 

Time - milliseconds 

Figure 14.—Computed D-t responses for hypothetical structure using P-t curves in Figure 12 as input for 

structural analysis. Calculated displacements are offset in time for clarity. 
 

Comments on Smoothing 

The P-t data reported here are raw data. All data reported came from the NI system in the 

LLEM, which records data at 1,500 samples per second for 5 sec. In prior NIOSH publications, the 

P-t data reported were smoothed data derived from the raw data using a 15-point moving-average 

algorithm. In this simple algorithm, the midpoint (point 8) in a 15-point data set is replaced with the 

average value of those 15 data points. Each data point in the moving 15-point set is given equal weight 

in the averaging. This smoothing algorithm tends to remove the highest peaks in the pressure data. 

It will also slow the rate of change in the pressure data, i.e., the rise time for fast pressure changes due 

to blast waves and other pressure transients will decrease. Although this smoothing algorithm can 

remove spurious data points due to noise or other transients in the data acquisition system, structural 

analysis requires the use of the raw data. The actual peak pressures and rise times measured are within 

the capabilities of the instruments and data acquisition system. True peak pressures and pressure-rise 

times are important when computing the response of a structure to some applied load. Because the data 

reported here are raw, there will be discrepancies with the smoothed (15 points, or over a 10-ms-wide 

moving window) peak pressures reported in previous NIOSH reports. The pressure data herein are 

always higher than data reported previously. 

GENERAL CONSTRUCTION DETAILS FOR CATEGORY 1 THROUGH 6 SEALS
 

Category 1 Seals: Concrete or Concretelike Materials With 

Internal Steel Reinforcement and Anchorage to Rock 

Category 1 seals are made of concrete or concretelike materials such as shotcrete or gunite. 

The seal structure contains internal steel reinforcement and is anchored to the surrounding rock with 

steel reinforcement bars. Two varieties of 20-psi seals are reported here—the Insteel 3-D seal from 

Precision Mine Repair, Inc., made with shotcrete and steel reinforcement bar, and the Meshblock seal 

from R. G. Johnson Co., Inc., made with pumped cement or shotcrete and steel reinforcement bar. 

Category 1A seal: Insteel 3-D seal – shotcrete with reinforcement 

The Insteel 3-D seal made by Precision Mine Repair, Inc., is constructed with shotcrete, steel 

reinforcement bar, and reinforcement wire. Steel reinforcement bars also anchor the seal to the surrounding rock. NIOSH researchers tested seven different structures using these concepts and materials 

during development of a seal that met the previous 20-psi seal design standard (Table 1). Test results 

from one of these structures were reported by Sapko et al. [2005]. 

Figures 15 and 16 show front-, plan-, and side-view drawings of the Insteel 3-D seal for the 

former 20-psi seal design standard. The seal consists of a three-dimensional welded wire space frame 

called an Insteel 3-D panel that is encased in concrete. The structural components of the seal are the 

rear Insteel 3-D panel with Stayform backing, the front Insteel 3-D panel without Stayform backing, 

#3 steel reinforcement bars laid horizontally from rib to rib within the Insteel 3-D panels, a plane of 

vertical #8 reinforcement bars and #8 reinforcement bar anchors into the roof and floor in front of each 

Insteel 3-D panel, and horizontal #8 reinforcement bar anchors into each rib. The panels are filled completely with fast-setting concrete mix applied from the front side of the seal using a shotcrete machine 

at a pressure of 100 psi. This mix hardens within 15 min and is nearly fully cured to design strength 

21 
within 24 hr. The minimum design uniaxial compressive strength requirement of this shotcrete is 

2,500 psi. The finished seal is at least 11.5 in thick. 

To construct the seal, the rear Insteel 3-D panels are trimmed to fit opening dimensions at the 

installation site and laid horizontally across the opening. Each horizontal panel contains a #3 steel 

reinforcement bar laid horizontally from rib to rib and spaced less than 16 in apart. The rear panel contains Stayform backing on the inby side, which serves as a backing for spraying the shotcrete from the 

outby side. Figure 17 shows a closeup view of a rear Insteel 3-D panel with the Stayform backing. 

Vertical holes are drilled into the roof and floor for two rows of 36-in-long, #8 steel 

reinforcement bar anchors. The holes are at least 12 in deep and evenly spaced across the entry on less 

than 24-in centers. The front and rear rows of holes are offset laterally from each other (Figure 15). 

Figure 15.—Front-, plan-, and side-view drawings of Category 1A structure: Insteel 3-D seal from Precision 

Mine Repair, Inc. 

The #8 steel reinforcement bar anchors in the rear row are epoxy-grouted in place, and vertical 

#8 reinforcement bars are tied in place using preformed clamps between corresponding roof and floor 

anchors. The rear Insteel 3-D panel with Stayform backing is then tied with wire to the rear row of 

vertical #8 steel reinforcement bar. Three holes are also drilled on 24-in centers into each rib at least 

12 in deep for additional anchorage, and #8 steel reinforcement bar anchors are epoxy-grouted into 

place and tied to the #3 steel reinforcement bars within the Insteel 3-D panels. Figure 18 shows the 

reinforcement construction at this stage. 

22 
Figure 16.—Detailed plan-view drawing of Category 1A structure: Insteel 3-D seal from Precision Mine Repair, Inc. 

 Figure 17.—Closeup of a rear Insteel panel with Stayform backing and the horizontal #3 steel 

reinforcement bars. 

23 
Figure 18.—Insteel 3-D seal under construction showing the rear Insteel 

panel with Stayform backing, one plane of vertical #8 steel reinforcement 

bars and anchors, the horizontal #8 steel reinforcement bar anchors, and 

the horizontal #3 steel reinforcement bars. 

The front Insteel 3-D panels without Stayform backing are then trimmed to fit the opening 

dimensions and laid horizontally in front of the rear plane of vertical #8 steel reinforcement bar. The 

front row of #8 steel reinforcement bar anchors is epoxy-grouted into place, and vertical #8 steel 

reinforcement bars are tied in place using preformed clamps between corresponding roof and floor 

anchors. The front Insteel 3-D panel is tied with wire to the front row of vertical #8 steel reinforcement 

bars. Figure 19 shows the reinforcement construction at this stage. The wire mesh and steel reinforcement bar network is now ready for spraying with shotcrete with a minimum design uniaxial compressive strength of 2,500 psi to a depth of at least 11.5 in. 

24 
 

Figure 19.— Insteel 3-D seal under construction with the addition of the front 

Insteel panel and the front plane of vertical #8 steel reinforcement bars. 

Category 1B seal: Meshblock seal – shotcrete with reinforcement 

The Meshblock seal made by R. G. Johnson Co., Inc., is constructed with shotcrete, steel 

reinforcement bar, and reinforcement wire. Steel reinforcement bars also anchor the seal to the surrounding rock. NIOSH researchers tested six different structures using these concepts and materials 

during development of a seal that met the previous 20-psi seal design standard (Table 1). Weiss et al. 

[1999] and Sapko et al. [2005] provide additional construction details and test results for seals in this 

category, along with some test results. 

Figure 20 shows front-, plan-, and side-view drawings of the Meshblock for the previous 20-psi 

seal design standard. The seal consists of three-dimensional welded-wire Meshblocks that are pumped 

full with concrete. The major structural components of the seal are a plane of vertical #8 steel 

reinforcement bars and #8 steel reinforcement bar anchors that attach the seal to the roof, floor, and 

both ribs. Figure 21 shows part of a typical Meshblock, which is made from 6-in by 6-in welded-wire 

mesh overlain by metal hardware cloth. The diameter of the 6-in by 6-in welded wires is about 0.16 in, 

25 
and the opening size in the hardware cloth is about 0.12 in. Overall dimensions for a Meshblock are 

42 in wide by 18.25 in high by 12 in deep. The space between the Meshblocks is filled with shotcrete 

(Figure 22). The shotcrete brand used is Quikrete MB-500, which is a mixture of cement and minus 

0.20-in aggregate and has a minimum design uniaxial compressive strength of 5,800 psi. 

To construct the seal, vertical holes are drilled 24 in deep into the roof and floor on 24-in 

centers. Additional horizontal holes are drilled 24 in deep into ribs on 40-in centers. Steel 

reinforcement bars, 48 in long and 1 inch in diameter, are resin-anchored into each hole (Figure 20). 

Vertical #8 steel reinforcement bars that overlap the anchor bars by 24 in are tied using preformed 

clamps to the corresponding roof and floor anchors. This reinforcement plane is centered in the 

Meshblock formwork. 

The Meshblock formwork is then pumped full with shotcrete. The metal hardware cloth facing 

on the Meshblocks allows the nozzleman to examine the shotcrete flowing into the formwork 

(Figure 22). Normally, two layers of Meshblock units are filled at a time. Care is required to limit 

pouring delays to less than 30 min to prevent cold joints in the finished structure. The top 6–12 in of 

the seal requires cutting and fitting the Meshblock units to create a back wall, which is filled in with 

the shotcrete using the spray nozzle. Finally, the perimeter is sprayed to stabilize and seal the surrounding strata. 

26 

Figure 20.—Front-, plan-, and side-view drawings of Category 1B structure: Meshblock seal from 

R. G. Johnson Co., Inc. 
Figure 21.—Closeup of Meshblock seal under construction showing the 

Meshblocks and the vertical #8 steel reinforcement bars and anchors. 

Figure 22.—Meshblock seal under construction showing the lower Meshblocks, 

the vertical #8 steel reinforcement bars and anchors, and placement of shotcrete. 

Category 2 Seals: Pumpable Cementitious Materials With No Steel Reinforcement 

and No Hitching 

Category 2 seals are also called pumpable seals and are made from cementitious materials of 

various compositions. Different formulations will produce different compressive strengths for the 

pumpable cementitious material. Lower-strength materials will require a thicker seal. These seals 

do not contain any internal steel reinforcement and are not hitched to the surrounding rock. Friction 

between the seal material and the surrounding rock holds the seal in place. Three varieties of 20-psi 

seals are reported here with different compressive strength materials and different seal thicknesses. 

27 
Category 2A seal: Pumpable cementitious material with uniaxial compressive strength of 

200 psi constructed 48 in thick 

Category 2A seals include Tekseal manufactured by Minova, Inc., and Celuseal manufactured 

by R. G. Johnson Co., Inc. These seals are made from a pumpable cementitious material with a minimum design uniaxial compressive strength of at least 200 psi and a thickness of at least 48 in. NIOSH 

researchers tested four different structures in this category during development of a seal that met the 

previous 20-psi seal design standard (Table 1). Greninger et al. [1991], Weiss et al. [1993, 1996], 

Weiss and Harteis [2008], and Sapko et al. [2005] provide additional details on constructing the 

pumpable, cementitious material seals in this category along with some test results. 

Figure 23 shows front-, plan-, and side-view drawings of the typical formwork for a pumpable 

cementitious material seal. The two form walls must have sufficient strength to resist the pressure from 

the uncured cementitious seal material. The formwork shown in Figures 23 and 24 consists of 4-in by 

4-in vertical wood posts installed on 3-ft centers across the entry, 1-in by 6-in wood boards nailed horizontally across the timbers on less than 2-ft centers, and MSHA-approved brattice material nailed to 

the inside of the frame. The brattice material must overlap approximately 4 in and is secured onto each 

rib, the roof, and the floor. The forms do not add any significant structural strength to the seal. Finally, 

the volume between the two forms is pumped full of cementitious material (Figure 25). 

28 

Figure 23.—Front-, plan-, and side-view drawings of Category 2 structure made from pumpable cementitious 

materials with no steel reinforcement and no hitching. 
 Figure 24.—Formwork for a typical pumpable seal showing the vertical posts, 

the horizontal boards, and the brattice liner (partially removed). 

 Figure 25.—Inside the formwork of a typical pumpable seal showing the brattice liner and the cementitious filling material. 

Tekseal and Celuseal are both lightweight, noncombustible cement-based products. Cementitious powder, water, and air are metered into a continuous mixer and then pumped between the forms. 

The amount of cementitious material used per cubic yard of seal determines the density and strength of 

the seal material. These seals should normally be installed using a continuous pour during construction 

so that a solid plug with no cold joints is obtained. 

29 
 

 

 

Category 2B seal: Pumpable cementitious material with uniaxial compressive strength of 

433 psi constructed 36 in thick 

Category 2B seals include the Ribfill seal made by HeiTech Corp. Again, these seals are made 

from a pumpable cementitious material with a minimum design uniaxial compressive strength of at 

least 433 psi and a thickness of at least 36 in. NIOSH researchers tested one structure in this category 

during development of a seal that met the previous 20-psi seal design standard (Table 1). Weiss et al. 

[2002] provide additional details on constructing the pumpable, cementitious material seals in this 

category along with test results. 

Construction of the seal uses a formwork similar to that shown in Figures 23 and 24, except 

that the distance between form walls is at least 36 in and the minimum design uniaxial compressive 

strength of the cementitious material must exceed 433 psi. 

Category 2C seal: Pumpable cementitious material with uniaxial compressive strength of 

480–600 psi constructed 24–30 in thick 

Category 2C seals include the Rockfast seals also made by HeiTech Corp. NIOSH researchers 

tested four different structures in this category during development of a seal that met the previous 

20-psi seal design standard (Table 1). Weiss et al. [2002] provide additional details on constructing the 

seals in this category along with test results. 

The Rockfast M-FGL material used for these seals is a modified, portland cement-based, fiberreinforced, pumpable grout that exhibits rapid gelation and high early strength. The 24-in-thick version 

of this seal requires material with a minimum design uniaxial compressive strength of 677 psi, while 

the 30-in-thick version requires material with a minimum design uniaxial compressive strength of 

480 psi. Construction of the seal uses a formwork similar to that shown in Figures 23 and 24, except 

that the distance between form walls is 24–30 in. 

Category 3 Seals: Articulated Structures – Solid and Hollow-Core Concrete Blocks 

With or Without Hitching 

Category 3 seals are articulated structures made from discrete concrete blocks bonded together 

with a mortar. These seals may or may not be hitched into the surrounding rock, and they do not contain any internal steel reinforcement. Two varieties of seal structures are reported here: the standard 

solid-concrete-block seal, which is hitched into the surrounding rock, and a variant of the standard seal 

that uses pressurized grout bags in lieu of hitching to attach the seal structure to the surrounding rock 

through friction. Also included in this category are ventilation stoppings made from solid and hollowcore concrete blocks. These stoppings are constructed by dry stacking the blocks without mortar and 

without hitching and only wedging along the ribs and roof. Test results from these structures are 

included here since these structures can form an integral part of other seal structures in other seal 

categories. 

30 
Category 3A seal: Standard solid-concrete-block seal with hitching 

The seal design in Category 3A is the original 20-psi standard seal, also known as the MitchellBarrett mine seal. The seal is constructed with wet-laid, solid concrete blocks, a central pilaster for 

added strength, and hitching into the ribs and floor. NIOSH researchers tested seven different structures in this category (Table 1). Greninger et al. [1989, 1991], Weiss et al. [1993, 1996] and Sapko 

et al. [2005] provide additional details on constructing the standard solid-concrete-block seals in this 

category along with test results. 

Figure 26 shows front-, plan- and side-view drawings of the typical standard solid-concreteblock seal as constructed in the LLEM. The seal is constructed with solid concrete blocks measuring 

either 8-in by 8-in by 16-in or 6-in by 8-in by 16-in (laid flat) and placed with ASTM Type S mortar. 

The mortar is applied on all vertical and horizontal block joints to a nominal thickness of 3/8 in. The 

blocks in the first course are placed with their long axis parallel to the rib. Blocks in the second course 

are oriented perpendicular to the first course, and the front and back rows in this course may or may 

not be staggered. 

31 

Figure 26.—Front-, plan-, and side-view drawings of Category 3A structure: standard solid-concrete-block 

seal with simulated hitching. 
The seal is constructed 16 in thick with a center pilaster measuring 16 in wide by 32 in thick for 

added strength (Figures 26–27). Blocks are cut and laid on the last course so that a gap approximately 

1–2 in high exists between the top course of block and the mine roof (Figure 28). This gap is filled 

completely with mortar across the width and depth of the seal. No wedges are used in the seal construction. Finally, the faces on both sides of the seal are coated with mortar or other surface sealant 

approved by MSHA. 

 Figure 27.—Solid-concrete-block seal under construction showing 

the center pilaster and the fully mortared joints on all sides. 

 Figure 28.—In background, top of a solid-concrete-block seal showing 

small cut blocks and mortar filling at the seal top. 

In practice, the standard solid-concrete-block seal is hitched into the floor and rib by excavating 

at least 6 in into solid competent material. To simulate hitching during tests in the LLEM, NIOSH 

researchers use 6-in by 6-in by 0.5-in-thick steel angle (Figure 29), anchored on 18-in centers using 

1-in-diam by 9-in-long anchor bolts. The nominal uniaxial compressive strength of the block material 

is 1,900 psi, although recent full-scale block testing by Barczak and Batchler [2008] indicates a solidconcrete-block uniaxial compressive strength of 1,330–1,780 psi. Design uniaxial compressive 

strength of the mortar exceeds 1,900 psi. 

32 
Figure 29.—Completed solid-concrete-block seal without a center pilaster 

showing the angle iron hitch on the ribs and floor only. 

Category 3B seal: Solid-concrete-block seal with Packsetter Bags 

and without hitching 

The 20-psi seal design in Category 3B is similar to the standard solid-concrete-block design 

described above, except that Packsetter Bags distributed by Strata Mine Services are used in place of 

conventional hitching. NIOSH researchers tested three different structures in this category (Table 1). 

Weiss et al. [2002] provide additional details on constructing the concrete block with grout bag seals in 

this category along with test results. 

Figure 30 shows front-, plan-, and side-view drawings of the typical standard solid-concreteblock seal with Packsetter Bags as constructed in the LLEM. The seal is constructed with tongue-andgroove, solid concrete blocks measuring either 8 in by 8 in by 16 in or 6 in by 8 in by 16 in (laid flat) 

and placed with mortar on all surfaces to a nominal thickness of 3/8 in. The mortar used must meet 

ASTM C270-91a as Type N, S, or M mortar. BlocBond from Quikrete is also considered an acceptable 

mortar. The seal has a central pilaster measuring 16 in wide by 32 in deep. 

Construction of this seal begins with placement of the first course of tongue-and-groove block 

laid parallel to the rib in wet mortar to within 2 in of each rib. A Packsetter Bag is laid flat and positioned at least 6 in under the outside corners of the first course of blocks. Placement of wet-laid concrete blocks continues until the blocks come within 2–5 in of the roof and ribs. Packsetter Bags placed 

along the ribs and across the roof overlap adjacent bags by a minimum of 6 in and overlap the front 

and back face of the seal by at least 3 in. The top-right and top-left corner Packsetter Bags are placed 

with half the bag down the rib side and half the bag across the roof side of the seal. Because of possible 

rib and roof undulations, if the distance between seal and strata is up to 8 in due to a localized cavity, 

a spacer Packsetter Bag can be used. 

33 
Figure 30.—Front-, plan-, and side-view drawings of Category 3B structure: solid-concrete-block seal with 

Packsetter Bags. 

After all seal material and Packsetter Bags are in position, grout is pumped into the bags in a 

sequence beginning with the top-right and top-left bags, followed by the bags along the roof line, 

followed by the bottom-right and bottom-left bags, and concluding with the bags along the rib lines. 

Each bag is pressurized with grout to 36–44 psi using a compressor-driven or hand pump, and the bags 

will load the seal horizontally and vertically upon installation. The Packsetter Bag grout is a specially 

formulated portland cement-based mixture blended and packaged for Strata Mine Services by 

Quikrete. It develops a uniaxial compressive strength of 580 psi after 28 days. 

After the grout bags are filled, polyurethane foam is used to fill any small gaps at the roof and 

ribs or between Packsetter Bags. Finally, the outby side of the seal is coated with an MSHA-approved 

general-purpose sealant to minimize leakage through the seal. Figure 31 shows a nearly complete 

tongue-and-groove, solid-concrete-block seal with Packsetter Bags. 

34 
Figure 31.—Tongue-and-groove, solid-concrete-block seal with center pilaster 

using pressurized Packsetter grout bags in lieu of hitching around the seal 

perimeter. The worker is coating the seal with an approved sealant. 

Category 3C seal: Ventilation stoppings – solid and hollow-core concrete blocks 

Ventilation stoppings are sometimes constructed from dry-stacked solid or hollow-core concrete blocks. Numerous such stoppings have been explosion tested in the LLEM. Although this kind of 

ventilation stopping is not a seal, it is a type of articulated structure. Solid or hollow-core concrete 

blocks are often part of seal construction, serving either as an integral part of the seal structure or as a 

form wall for some other seal construction material. The applied loads and measured responses from 

tests on these ventilation stoppings may provide useful structural information for analyzing and designing other mine seals, so the test results are included here. NIOSH researchers tested eight different 

structures in this category (Table 1)—four constructed with solid concrete blocks and four with 

hollow-core concrete blocks. Weiss et al. [2008] provide additional details on constructing the ventilation stoppings in this category along with test results. 

Figure 32 shows front-, plan-, and side-view drawings of the typical ventilation stopping constructed with either solid or hollow-core concrete blocks. The hollow-core concrete blocks measure 

6 in by 8 in by 16 in and have a nominal uniaxial compressive strength for the block material of 

1,900 psi. Recent full-scale wall testing by Barczak and Batchler [2008] indicates a hollow-core concrete block uniaxial compressive strength of less than 1,000 psi. For three of the solid-concrete-block 

structures, the blocks also measure 6 in by 8 in by 16 in; for the other structure, the blocks measure 

8 in by 8 in by 16 in. The nominal uniaxial compressive strength of the solid-concrete-block material 

was 1,900 psi. However, recent full-scale wall testing by Barczak and Batchler [2008] indicated a 

solid-concrete-block compressive strength of 1,330–1,780 psi. 

Wood wedges are used to tighten each course of blocks along the ribs and on the top course of 

blocks against the roof (Figures 32–33). Finally, a layer of Quikrete BlocBond sealant is applied to 

both faces of the stopping (Figure 34). 

35 
36 

Figure 32.—Front-, plan-, and side-view drawings of Category 3C structure: solid or hollow-core concrete 

block ventilation stoppings. 
Figure 33.—Dry-stacked concrete block stopping showing wedges used to fit 

the stopping to ribs and small cut blocks and a wood plank at the top. 

 Figure 34.—Dry-stacked concrete block stopping showing 

application of an approved sealant to the surface. 

37 
Category 4 Seals: Polymer and Aggregate Materials Without Hitching 

The MICON 550 permanent ventilation seal constructed by MICON is the sole representative 

of the Category 4 seals. This seal is constructed with two dry-stacked hollow-core concrete block stopping walls separated by about 18 in and filled with a mixture of two-component polyurethane foam and 

crushed limestone aggregate. No hitching of this structure is used except through friction with the surrounding rock. We present data from only one structure in this category (Table 1). Weiss et al. [1996] 

provide additional details on constructing polymer and aggregate seals in this category along with test 

results. 

Figure 35 shows front-, plan-, and side-view drawings of the MICON 550 seal. The back drystacked, hollow-core concrete block wall is constructed first. Upon placement of the last block of each 

row, a wedge is driven between the block and rib to firmly tighten the blocks in that row. All notches 

and holes are filled with the largest block fragments possible and wedged in place. The back wall is 

coated on the outside surface with an MSHA-approved sealant for dry-stacked concrete block walls. 

Note that MSHA-approved sealants for dry-stacked walls are listed separately from general-purpose 

sealants. 

38 

Figure 35.—Front-, plan-, and side-view drawings of Category 4 structure: polymer and aggregate seal. 
The front block wall is constructed to a height of 2–3 ft depending on seal height, and the 

central portion of the front wall is constructed all the way to the roof in a pyramid shape (Figure 36). 

After one or two top blocks are in place, wedges are driven between the block and roof to hold the wall 

in place. 

Figure 36.—Polymer and aggregate seal from MICON showing the rear 

dry-stacked, hollow-core concrete block wall, the partially completed front wall, 

a polymer coating on the inside surface of the form walls, and an approved 

sealant on the outside surface of the form wall. 

With the back wall completed and part of the front wall in place, construction of the inner core 

can begin. Construction of the inner core continues simultaneously with additional construction of the 

front wall. The outside of the front wall is also coated with an MSHA-approved sealant for dry-stacked 

concrete block walls. Note that the concrete blocks must be dry for adequate bonding of the polyurethane foam in the inner core. 

The initial step in constructing the inner core is to coat the floor, the inside of the block walls, 

the roof, and the ribs within the core area with a high-density, 70 lb/ft3

 polymer to prevent moisture 

from affecting the density of the polyurethane core. This coating on the inner wall is indicated in 

Figures 35–36. Installation then proceeds as follows: 

1.	 A 4-in-thick layer of dry crushed limestone aggregate, ranging in size from 0.25 to 1 in, 

is placed as the initial lift. 

2.	 The initial layer of limestone is completely coated with polyurethane foam (Figure 37) having 

a density of at least 10 lb/ft3

. As the polymer reacts, it expands and rises through with the 

crushed limestone, then hardens within 5 min. 

3.	 Steps 1 and 2 are repeated to the roof to complete the seal. 

The polyurethane foam and aggregate core must achieve a density of at least 35 lb/ft3 after curing for 

24 hr. 

The dry-stacked and coated concrete block walls remain in place after seal construction since 

these walls are an integral part of the structure. If the wall deteriorates, it will require repair. Any 

exposed polyurethane is coated with an MSHA-approved fire-retardant sealant, both immediately after 

seal construction and at any later time in the life of the seal. 

39 
Figure 37.—Polymer and aggregate seal from MICON showing the rear and 

front form wall, the polymer coating on the inner surfaces of the form walls, and 

the polyurethane foam and aggregate mixture filling the inner core of the seal. 

 

 

Category 5 Seals: Wood-Crib-Block Seals With or Without Hitching 

Category 5 seals made mainly from wood crib blocks are intended for use where high convergence is expected. These wood seals crush substantially, but may still retain their ability to resist 

explosion pressure and not leak air in or out of the sealed area. Two varieties of wood seals are 

described here: the wood-crib-block seal, which is nailed together and hitched into the surrounding 

rock; and a variant of this wood seal, which is glued together with construction adhesive and uses 

pressurized grout bags in lieu of hitching to attach the seal structure firmly to the surrounding rock. 

Category 5A seal: Wood-crib-block seal with hitching 

Category 5A wood crib seals are used in mines with high convergence where the forces resulting from convergence might crack the standard solid-concrete-block seal, rendering it ineffective. 

We have no data to report on this structure, but describe it here for completeness. Weiss et al. [1993] 

provide details on constructing wood-crib-block seals in this category. 

Figure 38 shows front-, plan-, and side-view drawings of the typical construction of a modified 

wood-crib-block seal. Crib blocks are at least 36 in long and measure either 5 in by 5 in or 6 in by 6 in. 

They are installed horizontally with their length parallel to the ribs. Each crib block is toenailed to the 

crib block in the lower course using three 4-in-long common nails spaced on 9-in centers, or a 0.5-inthick layer of rock dust is placed between courses of crib blocks (Figure 39). Voids around the perimeter are wedged tight. In practice, the seal is hitched into the ribs and floor by excavating into solid 

material at least 6 in. For testing in the LLEM, NIOSH researchers simulate hitching with 6-in by 6-in 

by 0.5-in-thick steel angle on the floor and ribs (Figure 40). The steel angle is anchored on 18-in 

centers using 1-in-diam by 9-in-long anchor bolts. Additionally, 5/8-in-thick exterior plywood sheeting 

is nailed on both sides of the seal using 4-in common nails on 6-in centers. An approved sealant is 

applied around the perimeter and at the joints in the plywood sheeting on both faces (Figure 40). 

40 
Figure 38.—Front-, plan-, and side-view drawings of Category 5A structure: wood-crib-block seal with 

plywood facing and simulated hitching. 

 

Figure 39.—Closeup of a hitched wood-crib-block seal showing the layer 

of rock dust placed between each layer of wood crib blocks. 

41 
Figure 40.—Construction of a hitched wood-crib-block seal without plywood facing 

showing the wood crib blocks separated by a rock dust layer, the angle iron hitching 

around the ribs and floor only, and the final coating with an approved sealant. 

Category 5B seal: Wood-crib-block seal with glue and Packsetter Bags 

Category 5B wood crib seals are also used in mines that have high convergence where other 

seals might fail because of cracking. The seals are constructed similar to the ordinary Category 5A 

wood-crib-block seals, except that Packsetter Bags are used in place of hitching. We present data from 

only one structure in this category (Table 1). Sapko et al. [2003] provide details on constructing the 

wood crib block with grout bag seals in this category. 

Figure 41 shows front-, plan-, and side-view drawings of the typical construction of a woodcrib-block seal with Packsetter Bags. The seal consists of 30-in-long wood crib blocks that measure 

from about 5-in by 5-in to 6-in by 6-in, appropriate glue and applicator, and Packsetter Bags with the 

necessary grout. Construction of the seal begins by applying a layer of adhesive to the mine floor. The 

first course of wood crib blocks is then laid across the floor or footer in the adhesive. The length of the 

crib block is oriented parallel with the ribs. No hitching to the roof, ribs, or floor is necessary. 

A Packsetter Bag is positioned under the corners of the first course of crib blocks by at least 6 in. The 

crib blocks are glued together with FOMO Handi-Stick adhesive and a special applicator (Figure 42). 

Each crib block requires three rows of adhesive about 0.5 in wide applied to the top and each side of 

each crib block along its entire length. 

In subsequent rows of crib blocks, the vertical joints are staggered (Figures 41 and 43). The 

wood crib blocks are placed to within 2–5 in of the roof and ribs to allow space for the Packsetter 

Bags. The bags along the ribs and across the roof overlap adjacent bags by a minimum of 6 in and the 

front and back face of the seal by at least 3 in. The top-right and top-left corner Packsetter Bags are 

placed with half the bag down the rib side and half the bag across the roof side of the seal. A spacer 

Packsetter Bag is used to fill gaps up to 8 in caused by rib and roof undulations. The Packsetter Bag 

grout is a specially formulated portland cement-based mixture blended and packaged for Strata Products, Inc., by Quikrete and has a compressive strength of 580 psi after 28 days. 

After wood crib blocks and Packsetter Bags are in position, grout is pumped into the bags to a 

pressure of 50 psi in a sequence beginning with the top-right and top-left bags, followed by the bags 

42 
along the roof line, then the bottom-right and bottom-left bags, and concluding with the bags along the 

rib lines. This pressurization provides artificial horizontal and vertical loading on the seal upon 

installation. Polyurethane foam is used to fill any small gaps at the roof, ribs, or between Packsetter 

Bags. The active mine side of the seal is covered with brattice secured with several pieces of wood 

nailed to the seal. The brattice overlaps the seal perimeter at the roof, rib, and floor by at least 1 ft. 

Finally, the active mine side of the seal is coated with an MSHA-approved general-purpose sealant. 

Figure 41.—Front-, plan-, and side-view drawings of Category 5B structure: wood-crib-block seal with 

Packsetter Bags. 

43 
 

Figure 42.—Construction of a wood-crib-block seal with pressurized 

Packsetter grout bags in lieu of hitching showing the application of glue 

between all wood-crib-block surfaces. 

 

Figure 43.—Construction of a wood-crib-block seal with pressurized Packsetter grout 

bags in lieu of hitching showing the glued wood crib blocks and the grout bags used 

along the roof and ribs. The active-mine-side surface is later covered with brattice and 

coated with an approved sealant. 

44 
 

 

Category 6 Seals: Articulated Structures – Lightweight Blocks 

With or Without Hitching 

Category 6 seals are articulated structures made from lightweight Omega blocks manufactured 

by Burrell Mining Products International, Inc. The Omega blocks are noncombustible, glass-fiber 

reinforced blocks measuring 8 in by 16 in by 24 in, weighing about 46 lb and having a compressive 

strength of 70–110 psi. The blocks can be cut with a handsaw to fit into spaces between seal and rib or 

roof where full blocks will not fit. Two varieties of seal structures composed of lightweight blocks are 

reported here: 24-in-thick seals that require hitching and 40-in-thick seals that do not require hitching. 

In Omega block seal construction, all horizontal and vertical joints are coated with 0.25-inthick BlocBond mortar manufactured by Quikrete Company. BlocBond, a mortar mix containing portland cement, fiberglass fiber, and additives, is the only mortar permitted in the construction of Omega 

Block seals. A layer of BlocBond is applied to the floor for setting the first course of blocks. BlocBond 

is also placed between the blocks and the coal ribs and between the top blocks and the mine roof. 

Loose material is brushed off of each block, then blocks are wetted before applying the BlocBond. 

Finally, all outside faces are coated completely with a 0.25-in-thick layer of the BlocBond mortar. 

Category 6A seal: Lightweight blocks 24 in thick with hitching 

The Category 6A 20-psi seal designs are made with Omega blocks constructed 24 in thick with 

a 48-in by 48-in center pilaster for added strength. NIOSH researchers tested two different structures in 

this category (Table 1). Sapko et al. [2005] and Cashdollar et al. [2007] provide additional details on 

constructing the lightweight block seals in this category along with test results. 

Figure 44 shows front-, plan-, and side-view drawings, and Figure 45 shows the construction of 

this Omega block seal with hitching. All block surfaces are coated with a 0.25-in-thick layer of 

BlocBond mortar. Two wood planks are placed across the top of the blocks and wedged against the 

roof (Figure 46). Wood planks are also placed on top of each pilaster and wedged against the roof. 

Spaces between the wood planks and wedges are filled with BlocBond mortar. To simulate hitching 

during the LLEM tests, NIOSH researchers use a 6-in by 6-in by 0.5-in-thick steel angle on the floor 

and ribs that is anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolts. Figure 47 

shows a completed Omega block seal with the angle iron to simulate hitching. 

45 
 Figure 44.—Front-, plan-, and side-view drawings of Category 6A structure: lightweight block seal, 

24 in thick with hitching. 

 Figure 45.—Construction of a 24-in-thick Omega block seal with hitching 

and a center pilaster. All surfaces are coated with BlocBond mortar. 

46 
 Figure 46.—Construction of an Omega block seal showing the wood board 

and wedges used to secure the seal at the roof. 

 Figure 47.—Completed 24-in-thick Omega block seal showing 

the angle iron hitch along the ribs and floor and the outer surface 

coated with an approved sealant. 

Category 6B seal: Lightweight blocks 40 in thick without hitching 

The Category 6B 20-psi seal designs are made with Omega blocks constructed 40 in thick and 

without a center pilaster for added strength or simulated hitching with steel angle at the floor and ribs. 

NIOSH researchers tested eight different structures in this category (Table 1). Weiss et al. [1993, 

1996], Weiss and Harteis [2008], Sapko et al. [2003], and Cashdollar et al. [2007] provide additional 

details on constructing the lightweight block seals in this category along with test results. 

Figure 48 shows front-, plan-, and side-view drawings of the typical Omega block seal without 

hitching. Figure 49 shows the same seal design under construction. Joints in alternate courses of blocks 

are staggered. Three rows of 1-in by 12-in wood planks are placed from rib to rib across the top of the 

47 
seal. One row of planks is placed along the center of the seal; the other two rows are placed with their 

edges flush with the inby and outby faces of the seal, respectively. Joints in the planking are staggered, 

and the planking is set in a thin layer of BlocBond. Wedges are driven on 6- to 12-in centers between 

the planks and roof to compress the planks uniformly against the Omega blocks. BlocBond is used to 

fill all the gaps between the mine roof and the top block course, including the areas between the rows 

of wood planks and the gaps between the wooden wedges. Finally, all exposed wood and the outside 

faces are coated with BlocBond. 

48 

 Figure 48.—Front-, plan-, and side-view drawings of Category 6B structure: lightweight block seal, 

40 in thick without hitching. 
Figure 49.—Construction of a 40-in-thick Omega block seal without hitching 

and no center pilaster. All surfaces are coated with BlocBond mortar. 

STRUCTURAL TESTING DATA FOR 20-psi COAL MINE SEALS 

Table 1 provides an overview of the NIOSH testing program on 44 different seal structures and 

8 stoppings. As the table indicates, the program subjected many structures to multiple or repeated pressure loads and tested many structures to failure. For some of the structures tested, the only data available are the applied P-t curve and an indicator of whether the structure survived or failed under that 

applied load. However, for most of the tests, the applied P-t curve and the measured D-t response are 

reported here. 

Tables 5 through 10 provide expanded information for each of the six seal categories, including 

the structure number for each individual seal structure constructed and tested, the type and number of 

tests on that structure, the loading condition on that structure (static or reflected, nonuniform or uniform), a reference figure that most closely describes that structure, and a brief description of the structure. Again, the test program includes 52 separate structures (44 seals and 8 stoppings). 

Table A-1 in the appendix provides detailed information for each seal structure and each test 

on that structure. Column 1 in the table gives the seal category and structure, a brief description, 

the name of the manufacturer or constructor, NIOSH publications related to that particular seal 

structure, and the name of the Excel file containing the raw data for the P-t and D-t curves associated 

with that seal. The Excel data files will be posted and available on the NIOSH Mining Web site 

(http://www.cdc.gov/niosh/mining). 

Column 2 in Table A-1 gives the location where the structure was constructed and tested; 

the exact height, width, and thickness for that particular seal structure; the type of test from previous 

tables; and the loading condition (also from previous tables). For most of the LLEM explosion tests, 

the location is the crosscut number between either the A- and B-drifts or B- and C-drifts. Other structures were tested in the small or large hydrostatic test chambers in the LLEM. 

For each unique structure tested, column 3 in Table A-1 gives a detailed description of how that 

seal was constructed. This information comes directly from the LLEM test descriptions. Although the 

construction details will generally follow the descriptions given in the previous section, each structure 

49 
 

tested is unique. For example, the shotcrete thickness in the Category 1A seals will vary from structure 

to structure, and the steel reinforcement may change somewhat from structure to structure. Those 

details, if available, are provided in the description in column 3. 

Column 4 in Table A-1 gives the LLEM test numbers that subjected the particular structure to 

an explosion loading. Each explosion test in the LLEM since the inception of the facility in 1983 has 

been assigned a sequential number. As indicated in Table 1, most of the structures reported herein were 

subjected to multiple explosion loadings prior to either failure of that structure or cessation of further 

testing. Note that individual LLEM tests will generally load from three to five different structures during the same test. 

Column 5 in Table A-1 indicates the test outcome. Either the structure withstood the explosion 

without significant damage, was damaged to some degree, or failed catastrophically, foregoing the 

possibility of any further test loadings. 

Column 6 in Table A-1 gives the maximum pressure to which the structure was subjected during the explosion test. The pressure data reported are from the raw test data (nonsmoothed). 

Column 7 in Table A-1 gives the maximum displacement recorded, if available. As indicated 

in Table 1, D-t data from an LVDT exist for most of the 52 structures tested and are reported here. 

In many of the earlier explosion tests of seal structures, NIOSH researchers did not measure the 

D-t response of the structure with an instrument. Seal testing and approval at the time were based on a 

pass or fail explosion test, and there was usually no immediate need for measuring the structural 

response. 

Column 8 in Table A-1 refers to the figure in the appendix that graphically displays the applied 

P-t curve and the measured D-t response of the structure to each explosion or water pressure test. 

These plots and the data they contain are valuable for calibrating and verifying computer models for 

the structural response of seals. Most of these plots had not been previously published, as such structural information was not necessary in the “build and test” approach used for the previous 20-psi seal 

designs [Gadde et al. 2007]. 

Data available for certain seal subcategories should enable model calibration and extrapolation 

to new seal designs and possible development of structure failure criteria for various seal designs. 

Available data for other seal subcategories are less complete, since NIOSH researchers may have conducted studies in those subcategories prior to 1997 and that information is no longer available. Below 

are discussions on the structural data available for each seal subcategory. 

Category 1A: Insteel 3-D seal – shotcrete with reinforcement.—This data set includes tests on 

seven different structures where all seven data sets have both the P-t and D-t curves. For structural 

analysis, the best data sets come from structures 1, 4, and 7, which were constructed similar to the 

schematic shown in Figure 15. Structures 1 through 6 were subject to a static, nonuniform explosion 

pressure that swept across the seal face, whereas structure 7 was subject to a static, uniform, water 

pressure load from a hydrostatic chamber test (Table 5). Test data from structures 4 and 7, plus data 

from structure 1, which is a thinner version of the same, should provide useful information for 

developing structural failure criteria for these seal designs and similar structures. Structures 2, 3, 5, and 

6 are variations of the seal geometry shown in Figure 15; these data sets may also contribute to model 

calibration and failure criteria development. 

50 
Category 1B: Meshblock seal – shotcrete with reinforcement.—This data set includes tests on 

six different structures. Unfortunately, good D-t data are not available from any of the tests. Structures 2 and 3 were constructed exactly as shown in Figure 20. Structures 4, 5, and 6 are thinner versions of the previous structures, but are constructed similar to the schematic shown in Figure 20. 

Structure 1 has some resemblance to the construction shown in Figure 20, but is much thicker and 

may be more akin to the Category 2 pumpable cementitious material seals. Each structure was loaded 

repeatedly by a static, nonuniform explosion pressure that swept across the seal face (Table 5). Three 

of those structures survived and three failed during the last test. This data set should provide a good 

basis for model calibration and possible development of a failure criterion. 

51 

Table 5.—Summary of Category 1 seal structures: concrete with steel reinforcement 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition 

Reference 

figure Structure description 

CATEGORY 1A 

Insteel 3-D seal: Concrete or concretelike materials with internal steel reinforcement and anchorage to rock 

1 

2 

3 

Explosion 

Explosion 

Explosion 

1 

1 

1 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Similar to 

Figure 15 

Similar to 

Figure 15 

Similar to 

Figure 15 

1 Insteel 3-D panel, 1 plane of steel reinforcement, 

 7-in-thick shotcrete 

1 Insteel 3-D panel, 1 plane of steel reinforcement, 

 3-in-thick foam core, 3-in-thick shotcrete on both sides 

1 Insteel 3-D panel, 1 plane of steel reinforcement, 

 3-in-thick foam core, 1.5-in-thick shotcrete on one 

 side, 3-in-thick shotcrete on other side 

4 

5 

6 

7 

Explosion 

Explosion 

Explosion 

Hydrostatic 

1 

1 

1 

1 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Uniform 

Identical to 

Figure 15 

Based on 

Figure 15 

Based on 

Figure 15 

Identical to 

Figure 15 

2 Insteel 3-D panels, 2 planes of steel reinforcement, 

 12-in-thick shotcrete 

1 Insteel 3-D panel, 1 plane of steel reinforcement, 

 8-in-thick shotcrete, 48-in-wide pilaster in center 

1 Insteel 3-D panel, 1 plane of steel reinforcement, 

 8-in-thick shotcrete, 48-in-wide pilaster in center 

2 Insteel 3-D panels, 2 planes of steel reinforcement, 

 12-in-thick shotcrete 

CATEGORY 1B 

Meshblock seal: Concrete or concretelike materials with internal steel reinforcement and anchorage to rock 

1 

2 

3 

4 

5 

6 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

20 

5 

3 

2 

2 

2 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Similar to 

Figure 20 

Identical to 

Figure 20 

Identical to 

Figure 20 

Similar to 

Figure 20 

Similar to 

Figure 20 

Similar to 

Figure 20 

1 plane of steel reinforcement, 4-ft-thick seal with

 533-psi compressive strength material 

13 in thick with 4,200-psi compressive strength material 

13 in thick with 4,200-psi compressive strength material 

7 in thick with 4,200-psi compressive strength material 

3 in thick with 4,200-psi compressive strength material 

1.75 in thick with 4,200-psi compressive strength 

material 
Category 2A: Pumpable cementitious material with compressive strength of 200 psi constructed 48 in thick.—This data set includes tests on four different structures, all of which have good 

P-t and D-t data. Two of the structures were loaded repeatedly, and three were eventually loaded to 

failure. Construction of these structures is identical to that shown in Figure 23. Structure 1 was subject 

to a reflected explosion pressure that was uniform across the seal face; structures 2, 3, and 4 were 

subject to static, uniform pressure developed by methane ignition tests and water pressure tests in a 

hydrostatic test chamber (Table 6). This data set should provide an excellent basis for model calibration and possible development of a failure criterion. 

Table 6.—Summary of Category 2 seal structures: pumpable cementitious materials 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition 

Reference 

figure Structure description 

CATEGORY 2A 

Pumpable cementitious materials: 200 psi and 48 in thick, no steel reinforcement and no hitching 

1 

2 

3 

4 

Explosion 

Hydrostatic 

Hydrostatic 

Hydrostatic 

2 

1 

3 

1 

Reflected 

Uniform 

Static 

Uniform 

Static 

Uniform 

Static 

Uniform 

Similar to 

Figure 23 

Identical to 

Figure 23 

Identical to 

Figure 23 

Identical to 

Figure 23 

48 in thick with 143-psi compressive strength

 material with retrofit 

48 in thick with 350-psi compressive strength

material 

48 in thick with 350-psi compressive strength

material 

48 in thick with 350-psi compressive strength

material 

CATEGORY 2B 

Pumpable cementitious materials: 433 psi and 36 in thick, no steel reinforcement and no hitching 

1 Explosion 2 Static 

Nonuniform 

Identical to 

Figure 23 

36 in thick with 450- to 500-psi compressive

strength material 

CATEGORY 2C 

Pumpable cementitious materials: 480–600 psi and 24–30 in thick, no steel reinforcement and no hitching 

1 

2 

3 

4 

Explosion 

Explosion 

Explosion 

Explosion 

2 

2 

2 

4 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Similar to 

Figure 23 

Identical to 

Figure 23 

Identical to 

Figure 23 

Identical to 

Figure 23 

34 in thick with 600- to 840-psi compressive

 strength material, 1 plane of steel reinforcement 

30 in thick with 390- to 565-psi compressive

 strength material 

24 in thick with 600- to 750-psi compressive

 strength material 

30 in thick with 597-psi compressive strength

 material 

Category 2B: Pumpable cementitious material with compressive strength of 433 psi constructed 36 in thick.—This data set includes just one structure identical to that shown in Figure 23. 

The structure was loaded twice by a static, nonuniform explosion pressure that swept across the seal 

face, but it did not fail. While P-t data are available, D-t data are not. This data set provides a limited 

basis for model calibration and extrapolation; however, it provides some data on the structural 

behavior of stronger construction materials. 

Category 2C: Pumpable cementitious material with compressive strength of 480–600 psi 

constructed 24–30 in thick.—This data set includes tests on four different structures, all of which were 

loaded repeatedly and all of which survived. D-t data are available for just one of these structures. 

Construction of these structures is identical to that shown in Figure 23. The structures were loaded by a 

static, nonuniform explosion pressure that swept across the seal face. This data set provides a limited 

basis for model calibration and extrapolation; however, it does provide additional data on the structural 

behavior of stronger construction materials. 

52 
 

 

 

 

Category 3A: Standard solid-concrete-block seal with hitching.—This data set includes tests 

on seven distinct structures, five of which were subject to repeated pressure loads and three of which 

were loaded to failure. Complete P-t data are presented for each test on all seven structures, and 

D-t data are available for each test on six of the seven structures in this subcategory. Construction of 

these structures is identical to that shown in Figure 26, except for structure 1, which lacks the center 

pilaster. The structures were loaded by different methods (Table 7). Structures 1 through 3 were loaded 

by a static, nonuniform explosion pressure that swept across the seal face. Structures 4 through 7 were 

loaded by a static, uniform pressure developed by methane ignition tests and water pressure tests in a 

hydrostatic test chamber. This data set should provide an excellent basis for model calibration and possible development of a failure criterion. 

Category 3B: Solid-concrete-block seal with Packsetter Bags and without hitching.—This 

data set includes tests on three structures where only one was loaded to failure. P-t data are available 

for all tests; however, no D-t data were recorded. Construction of structure 2 is identical to that shown 

in Figure 30, whereas structures 1 and 3 are similar. The structures were loaded by a static, nonuniform 

explosion pressure that swept across the seal face (Table 7). This data set may be combined with data 

from Subcategory 3A and 3C structures for model calibration and possible development of a failure 

criterion. 

Category 3C: Ventilation stoppings – solid and hollow-core concrete blocks.—This data set 

contains tests on eight different structures where all were loaded repeatedly and all failed eventually. 

Complete P-t data are available for all tests on all structures, and complete D-t data are available for all 

but one of the structures tested. Construction of these structures is identical to that shown in Figure 32. 

All structures were loaded by a static, nonuniform explosion pressure that swept across the stopping 

face (Table 7). Although this data set is not for mine seals per se, it has significant value for model 

calibration and development of failure criteria since concrete blocks, both solid and hollow-core, 

can be a significant part of many seal designs. These tests provide information on the arching behavior 

of articulated structures on a rigid foundation [Weiss et al. 2008]. 

Category 4: Polymer and aggregate materials without hitching.—This data set includes just 

one test on one structure, which resulted in failure. Both P-t and D-t data are presented. Dolinar et al. 

[2008] provide additional, new structural data on polymer and aggregate seals that were not incorporated into this report. Construction of this structure is similar to that shown in Figure 35. The structure 

was loaded by a static, uniform pressure developed by a methane ignition test in a hydrostatic test 

chamber (Table 8). This single test provides useful information for model calibration and possible 

development of a failure criterion. 

53 
Table 7.—Summary of Category 3 seal structures: articulated structures 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition Reference figure Structure description 

CATEGORY 3A 

Articulated structures: Standard solid-concrete-block seal with hitching 

1 

2 

3 

4 

5 

6 

7 

Explosion 

Explosion 

Explosion 

Hydrostatic 

Hydrostatic 

Hydrostatic 

Hydrostatic 

4 

10 

2 

5 

2 

1 

1 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Uniform 

Static Uniform 

Static Uniform 

Static Uniform 

Similar to Figure 26 

Identical to Figure 26 

Identical to Figure 26 

Identical to Figure 26 

Identical to Figure 26 

Identical to Figure 26 

Identical to Figure 26 

No center pilaster, but with hitching 

Center pilaster and with hitching 

Center pilaster and with hitching 

Center pilaster and with hitching 

Center pilaster and with hitching 

Center pilaster and with hitching 

Center pilaster and with hitching 

CATEGORY 3B 

Articulated structures: Standard solid-concrete-block seal with Packsetter Bags and without hitching 

1 

2 

3 

Explosion 

Explosion 

Explosion 

2 

2 

2 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Similar to Figure 30 

Identical to Figure 30 

Similar to Figure 30 

Center pilaster and with hitching, 

 mortared joints 

Center pilaster and no hitching, 

 mortared joints 

Center pilaster and no hitching, 

 dry-stacked blocks 

CATEGORY 3C 

Articulated structures: Ventilation stoppings – solid and hollow-core concrete blocks 

1 

2 

3 

4 

5 

6 

7 

8 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

2 

2 

6 

7 

6 

7 

10 

10 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Static Nonuniform 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Identical to Figure 32 

Dry-stacked, hollow-core concrete 

blocks 

Dry-stacked, hollow-core concrete 

blocks 

Dry-stacked, hollow-core concrete 

blocks 

Dry-stacked, hollow-core concrete 

blocks 

Dry-stacked, solid concrete blocks 

Dry-stacked, solid concrete blocks 

Dry-stacked, solid concrete blocks 

Dry-stacked, solid concrete blocks 

Table 8.—Summary of Category 4 seal structures: polymer and aggregate structures 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition 

Reference 

figure Structure description 

Polymer a

CATEGORY 4 

nd aggregate materials without hitching 

1 Hydrostatic 1 Static Similar to 11-in-thick polyurethane foam and 

Uniform Figure 35 aggregate core 

54 
 

 

 

 

Category 5A: Wood-crib-block seal with hitching.—No structural data are available. 

Category 5B: Wood-crib-block seal with glue and Packsetter Bags.—This data set contains 

test results from one structure that was loaded twice and survived both tests. P-t and D-t data are available for both tests. Construction of this structure is identical to that shown in Figure 41. The structure 

was loaded by a static, nonuniform explosion pressure that swept across the seal face (Table 9). This 

single test provides useful information for model calibration and possible development of a failure 

criterion. 

Table 9.—Summary of Category 5 seal structures: wood-crib-block structures 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition 

Reference 

figure Structure description 

CATEGORY 5A 

Wood-crib-block seal with hitching 

None — 0 — Similar to 

Figure 38 

— 

CATEGORY 5B 

Wood-crib-block seal with glue and Packsetter Bags 

1 Explosion 2 Static Identical to 30-in-thick wood-crib-block seal with 

Nonuniform Figure 41 Packsetter Bags 

Category 6A: Lightweight blocks, 24 in thick with hitching.—This data set contains results 

from tests on two different structures. All tests have both P-t and D-t data. Construction of these structures is identical to that shown in Figure 44. One structure was loaded by a static, nonuniform explosion pressure that swept across the seal face, while the other was loaded by a static, uniform pressure 

developed by a methane ignition test in a hydrostatic test chamber (Table 10). Both tests provide useful 

information for model calibration and possible development of a failure criterion. This data set is 

included for completeness, although lightweight blocks may or may not have use in future seal 

designs. 

Category 6B: Lightweight blocks, 40 in thick without hitching.—This data set includes results 

from tests on eight different structures. Three of the structures failed on the first test, three of the structures failed after repeated tests, and two survived repeated tests. Nearly complete P-t and D-t data are 

available for all tests on all structures. Construction of these structures is identical or very similar to 

that shown in Figure 48. As indicated in Table 10, four structures were loaded by a static, nonuniform 

explosion pressure that swept across the seal face. Three were loaded by a reflected explosion pressure 

that was uniform across the seal face; and one was loaded by a static, uniform pressure developed by a 

methane ignition test in a hydrostatic test chamber. All tests provide useful information for model calibration and possible development of a failure criterion; however, lightweight blocks may or may not 

have utility in future seal designs. 

55 
Table 10.—Summary of Category 6 seal structures: lightweight block structures 

Structure 

No. 

Type of 

test 

No. of 

tests 

Loading 

condition 

Reference 

figure Structure description 

CATEGORY 6A 

Articulated structures: Lightweight blocks, 24 in thick with hitching 

1 

2 

Explosion 

Hydrostatic 

2 

1 

Static 

Nonuniform 

Static 

Uniform 

Identical to 

Figure 44 

Identical to 

Figure 44 

Properly constructed, 24-in-thick Omega block 

 seal with hitching 

Properly constructed, 24-in-thick Omega block 

 seal with hitching 

CATEGORY 6B 

Articulated structures: Lightweight blocks, 40 in thick without hitching 

1 

2 

3 

4 

5 

6 

7 

8 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Explosion 

Hydrostatic 

4 

9 

2 

3 

1 

3 

1 

1 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Nonuniform 

Static 

Uniform 

Static 

Uniform 

Static 

Uniform 

Static 

Uniform 

Identical to 

Figure 48 

Identical to 

Figure 48 

Similar to 

Figure 48 

Similar to 

Figure 48 

Identical to 

Figure 48 

Similar to 

Figure 48 

Similar to 

Figure 48 

Identical to 

Figure 48 

Properly constructed, 40-in-thick Omega block 

 seal without hitching 

Properly constructed, 40-in-thick Omega block 

 seal without hitching 

40-in-thick Omega block seal without hitching, 

 mortar on horizontal joints but not on vertical joints 

40-in-thick Omega block seal without hitching, 

 mortar on horizontal joints but not on vertical joints 

Properly constructed, 40-in-thick Omega block 

 seal without hitching 

40-in-thick Omega block seal without hitching, 

 mortar on horizontal joints but not on vertical joints 

40-in-thick Omega block seal without hitching, 

 mortar on horizontal joints but not on vertical joints 

Properly constructed, 40-in-thick Omega block 

 seal without hitching 

56 
SUMMARY AND CONCLUSIONS 

The seal testing data presented in this report are organized into six broad categories of seal 

structures: 

1. Concretelike materials with steel reinforcement and rebar anchorage to rock 

2. Pumpable cementitious materials of varying compressive strengths with no steel reinforcement and no hitching 

3. Articulated structures such as solid-concrete-block seals and ventilation stoppings made of 

solid and hollow-core concrete blocks with or without hitching 

4. Polymer and aggregate materials without hitching 

5. Wood-crib-block seals with or without hitching 

6. Articulated structures such as lightweight blocks with or without hitching 

This report provides a general description, including figures for each seal category and subcategory. The specific construction detail for individual structures in each seal category is included in 

the tables in the appendix. The report also describes the LLEM and the general procedures used to load 

the test seals. NIOSH researchers used four distinct test procedures that subjected the test seals to different loading conditions: 

1. Explosion tests on seals in crosscuts that loaded seals with the static blast wave overpressure that is nonuniform across the face. 

2. Explosion tests on seals in C-drift that loaded seals with the reflected blast wave overpressure that is assumed uniform across the face. 

3. Hydrostatic chamber tests using water pressure that loaded seals with a static, nearly uniform pressure. 

4. Hydrostatic chamber tests using methane ignition pressure that loaded seals with a static 

overpressure that is assumed uniform across the face. 

The report discusses and analyzes the loading conditions and boundary conditions for the seal 

tests. The foundation conditions for the seal tests in the LLEM as reported here do not represent typical 

conditions found in underground coal mines. The rocks in the LLEM have much greater stiffness and 

strength than typical rocks found in underground coal mines, where the roof and floor rock and the 

coal ribs may have lower stiffness and strength. 

We report and analyze the sensors and data acquisition systems used during the tests to collect 

the pressure loading data and the displacement response of the test seals. We report the response time, 

time constant, and frequency response for various pressure and displacement transducers used throughout the tests. With regard to the P-t data, we conclude that the recorded data accurately reflect the 

actual pressure developed during the tests. Similarly, the recorded displacement data accurately capture 

the initial displacement response of the test seals. However, the displacement data are only reliable up 

to the initial peak displacement and not beyond that point in time due to the experimental method used 

to link the structure to the displacement transducer. 

The structural data reported herein were collected at a rate of 1,500 samples per second. The 

P-t data could contain higher-frequency components that are not recorded by the data acquisition system. We conducted structural analyses and demonstrated that the P-t data collected at 1,500 samples 

per second are adequate for structural analysis of seals under the conditions of the explosion tests conducted in the LLEM. 

57 
This report presents test data on a total of 52 different structures in the above 6 categories. The 

appendix presents the P-t curve and the D-t curve for 100 separate tests on these structures. In addition, 

the appendix provides the P-t curve but not the D-t curve for 66 other tests on the remaining structures. 

Table A-1 in the appendix indicates whether those structures survived or failed during the test. 

The structural data assembled in the appendix will facilitate future structural analysis in each of 

the various categories of seal structures. Certain data sets may lead to development of structure failure 

criteria for certain seal designs. Calibrating and validating structural models of seal behavior from 

20-psi explosion tests should enable reliable extrapolation of those structural models to the analysis of 

50- and 120-psi seal designs intended to meet the MSHA final rule for sealing of abandoned areas. 

REFERENCES 

73 Fed. Reg. 21182 [2008]. Mine Safety and Health Administration, 30 CFR part 75: sealing of 

abandoned areas; final rule. 

Barczak TM, Batchler TJ [2008]. Comparison of the transverse load capacities of various block 

ventilation stoppings under arch loading conditions. In: Wallace KG Jr., ed. Proceedings of the 12th 

U.S./North American Mine Ventilation Symposium (Reno, NV, June 9–11, 2008). Reno, NV: University of Nevada, pp. 225–231. 

Cashdollar KL, Weiss ES, Harteis SP, Sapko MJ [2007]. Experimental study of the effect of 

LLEM explosions on various seals and other structures and objects. Appendix X in: Gates RA, Phillips 

RL, Urosek JE, Stephan CR, Stoltz RT, Swentosky DJ, Harris GW, O’Donnell JR Jr., Dresch RA. 

Report of investigation: fatal underground coal mine explosion, January 2, 2006, Sago mine, Wolf Run 

Mining Company, Tallmansville, Upshur County, West Virginia, ID No. 46-08791. Arlington, VA: 

U.S. Department of Labor, Mine Safety and Health Administration. 

CFR. Code of federal regulations. Washington, DC: U.S. Government Printing Office, Office 

of the Federal Register. 

Dolinar DR [2008]. Personal communication. 

Dolinar DR, Sapko MJ, Harteis SP [2008]. Performance of a polyurethane core seal tested in a 

hydrostatic chamber. Pittsburgh, PA: U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS 

(NIOSH) Publication No. 2008–129, RI 9674. 

Esterhuizen GS [2008]. Personal communication. 

Gadde MM, Beerbower D, Rusnak JA, Honse J, Worley P [2007]. Post PIB P06-16: how to 

design alternative mine seals? SME preprint 07-130. Littleton, CO: Society for Mining, Metallurgy, 

and Exploration, Inc. 

Glasstone S, Dolan PJ, eds. [1977]. The effects of nuclear weapons. 3rd ed. U.S. Department of 

Defense and the Energy Research and Development Administration. 

Greninger NB, Weiss ES, Luzik SJ, Stephan CR [1989]. Performance evaluation of solid 

cementitious seals. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, Pittsburgh 

Research Center, Internal Report 4809. Unpublished. 

Greninger NB, Weiss ES, Luzik SJ, Stephan CR [1991]. Evaluation of solid-block and 

cementitious foam seals. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9382. 

NTIS No. PB 92-152115. 

Kinney GF [1962]. Explosive shocks in air. New York: Macmillan. 

Landau LD, Lifshitz EM [1987]. Fluid mechanics. Course of theoretical physics, vol. 6. 2nd ed. 

Oxford, U.K.: Butterwork-Heinemann. 

58 
Mattes RH, Bacho A, Wade LV [1983]. Lake Lynn Laboratory: construction, physical 

description, and capability. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, IC 8911. 

NTIS No. PB 83-197103. 

Sapko MJ, Weiss ES, Trackemas J, Stephan CR [2003]. Designs for rapid in situ sealing. SME 

preprint 03-010. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc. 

Sapko MJ, Weiss ES, Harteis SP [2005]. Methods for evaluating explosion-resistant ventilation 

structures. In: Gillies ADS, ed. Proceedings of the Eighth International Mine Ventilation Congress 

(Brisbane, Queensland, Australia, July 6–8, 2005). Carlton, Victoria, Australia: Australasian Institute 

of Mining and Metallurgy, pp. 211–219. 

Slawson TR [1995]. Wall response to airblast loads: the wall analysis code (WAC). Prepared 

for the U.S. Army Energy Research and Development Center, Vicksburg, MS. 

Triebsch G, Sapko MJ [1990]. Lake Lynn Laboratory: a state-of-the-art mining research laboratory. In: Proceedings of the International Symposium on Unique Underground Structures. Vol. 2. 

Golden, CO: Colorado School of Mines, pp. 75-1 to 75-21. 

Weiss ES, Harteis SP [2008]. Strengthening existing 20-psi mine ventilation seals with carbon 

fiber-reinforced polymer reinforcement. Pittsburgh, PA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, DHHS (NIOSH) Publication No. 2008–106, RI 9673. 

Weiss ES, Greninger NB, Stephan CR, Lipscomb JR [1993]. Strength characteristics and airleakage determinations for alternative mine seal designs. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9477. NTIS No. PB94-111275. 

Weiss ES, Slivensky WA, Schultz MJ, Stephan CR. Jackson KW [1996]. Evaluation of polymer construction material and water trap designs for underground coal mine seals. Pittsburgh, PA: 

U.S. Department of Energy, RI 9634. NTIS No. PB96-123392. 

Weiss ES, Cashdollar KL, Mutton IVS, Kohli DR, Slivensky WA [1999]. Evaluation of 

reinforced cementitious seals. Pittsburgh, PA: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication No. 99-136, RI 9647. 

Weiss ES, Cashdollar KL, Sapko MJ [2002]. Evaluation of explosion-resistant seals, stoppings, 

and overcast for ventilation control in underground coal mining. Pittsburgh, PA: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2003-104, RI 9659. 

Weiss ES, Cashdollar KL, Harteis SP, Shemon GJ, Beiter DA, Urosek JE [2008]. Explosion 

effects on mine ventilation stoppings. Pittsburgh, PA: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

DHHS (NIOSH) Publication No. 2009–102, RI 9676. 

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Krieger Publishing Co. 

59 
60 

APPENDIX.—DETAILED SUMMARY OF SEAL STRUCTURE TESTS AND TEST DATA

Table A-1.—Detailed summary of seal structure tests 

Seal category – Structure No.

Description 

Manufacturer

NIOSH reference 

Excel data file name1 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 1A SEALS 

Concrete or concretelike materials with internal steel reinforcement and anchorage to rock 

Insteel 3-D seal: Shotcrete with reinforcement, 7 structures tested 

Category 1A: Structure 1

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#1_1Test.xls 

A-B drifts, X-1 

19.75 ft wide by

6.67 ft high by

7 in thick 

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel with Stayform backing and 1 plane of reinforcement bar anchorage similar to 

Figure 15. The framework, which extends across the 

entire width of the crosscut, is anchored in place by rebar 

partially imbedded into the roof, ribs, and floor with the exposed sections of the rebar tie wired to the rebar contained within the framework with 3 on each rib and about 

10 each on the roof and floor. Shotcrete (203 bags of PakMix Pro Line concrete mix or 15,631 lb dry mix) is then applied to the entire structure from the active (B-drift) side 

to a total thickness of about 7 in. Nearly fully cured in 24 hr. Minimum compressive strength of shotcrete is 2,500 psi. 

419 No damage 45.8 1.0 A-1 

Category 1A: Structure 2 

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#2_1Test.xls 

A-B drifts, X-2 

21 ft wide by

6.75 ft high by

9 in thick 

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel without Stayform backing and 

1 plane of reinforcement bar anchorage similar to 

Figure 15. The framework contains, between the wire mesh outside panels and rebar, a 3-in foam insert. A temporary opening (large enough to allow for the 

passage of a person) was installed through this seal to allow for the shotcrete application on the sealed (A-drift) 

side of the seal. 3 in of shotcrete was applied to both sides. A total of 166 bags of Pak Mix Pro Line concrete mix or 12,782 lb of dry mix used for seal. A metal covering was installed within the opening, reinforced with rebar, 

and completely filled with shotcrete. Nearly fully cured in 24 hr. Minimum compressive strength of shotcrete is 2,500 psi. 

419 No damage 33.8 3.2 A-2 

1Excel data files will be posted and available on the NIOSH Mining Web site (http://www.cdc.gov/niosh/mining). 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum

displacement

data

(in) 

Appendix

figure

No. 

Category 1A: Structure 3

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#3_1Test.xls 

A-B drifts, X-3 

About 19 ft wide 

by 7 ft high 

by 7.5 in thick 

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel without Stayform backing and 

1 plane of reinforcement bar anchorage similar to 

Figure 15. The framework contains, between the wire mesh outside panels and rebar, a 3-in foam insert. 1.5 in of shotcrete (Pak Mix Pro Line concrete mix) was applied 

to the A-drift side. 3 in of shotcrete was applied to the 

B-drift side. Nearly fully cured in 24 hr. Minimum compressive strength of shotcrete is 2,500 psi. 

419 No damage 44.5 3.2 A-3 

Category 1A: Structure 4

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#4_1Test.xls 

A-B drifts, X-1 

18.67 ft wide by

7.5 ft high by

11.5 in thick

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel with Stayform backing, 1 plane of reinforcement bar anchorage, 1 front Insteel 3-D panel 

without Stayform backing, and another plane of reinforcement bar anchorage identical to Figure 15. The framework, which extends across the entire width of the 

crosscut, was anchored in place by #8 rebar partially

imbedded into the roof, ribs, and floor with the exposed sections of the rebar tie wired to the rebar contained within the framework. Shotcrete (362 bags of Pak Mix Pro 

Line concrete mix or 25,340 lb of dry mix) was then 

applied to the entire structure from the active (B-drift) side 

to a total thickness of about 11.5 in. Nearly fully cured in 24 hr. Minimum compressive strength of shotcrete is 2,500 psi. 

420 No damage 57.5 0.08 A-4 

61 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum

displacement

data

(in) 

Appendix

figure

No. 

Category 1A: Structure 5

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#5_1Test.xls 

A-B drifts, X-2 

About 19 ft wide 

by 7 ft high 

by 8 in thick 

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel with Stayform backing and 1 plane of reinforcement bar anchorage similar to 

Figure 15. This framework contained a 48-in-wide center pilaster on both sides. A hinged door, the entire height of the seal and about 2 ft wide, was designed on the inby rib 

end of the seal. This door was then secured with rebar 

prior to the shotcrete operations. Shotcrete thickness is approximately 8 in. Minimum compressive strength of 

shotcrete is 2,500 psi. 

420 No damage 45.9 3.2 A-5 

Category 1A: Structure 6

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Not previously reported by

NIOSH

Cat1A_Struct#6_1Test.xls 

A-B drifts, X-3 

18.25 ft wide by

7.4 ft high by

about 6 in thick

Explosion test 

Quasi-static

Nonuniform 

1 rear Insteel 3-D panel with Stayform backing and 1 plane of reinforcement bar anchorage similar to 

Figure 15. No door through the seal. Diagonal stiffener 

units on the A-drift side of the framework between the center pilaster and each rib. 255 bags of Pak Mix Pro cement mix or 20,400 lb of dry mix was used. Minimum 

compressive strength of shotcrete is 2,500 psi. 11.5 in thick at diagonal pilasters and 17.5 in thick at the 48-inwide center pilaster. 

420 No damage 45.1 NA A-6 

Category 1A: Structure 7

Shotcrete with reinforcement 

Precision Mine Repair, Inc. 

Insteel 3-D

Sapko et al. [2005] 

Cat1A_Struct#7_1Test.xls 

Small hydrostatic 

test chamber

21 ft wide by

8.5 ft high

11 in thick

Water test

Quasi-static

Uniform 

1 rear Insteel 3-D panel with Stayform backing, 1 plane of reinforcement bar anchorage, 1 front Insteel 3-D panel 

without Stayform backing, and another plane of reinforcement bar anchorage identical to Figure 15. The framework, which extends across the entire width of the 

crosscut, was anchored in place by #8 rebar partially

imbedded into the roof, ribs, and floor with the exposed sections of the rebar tie wired to the rebar contained within the framework. Shotcrete was then applied to the 

entire structure from the active side to a total thickness of about 11 in. Nearly fully cured in 24 hr. Minimum compressive strength of shotcrete is 2,500 psi. 

PR-1 No damage 27 0.22 A-7 

62 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 1B SEALS 

Concrete or concretelike materials with internal steel reinforcement and anchorage to rock 

Meshblock seal: Shotcrete with reinforcement, 6 structures tested 

Category 1B: Structure 1

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Aquablend plug seal between 

Gunmesh stoppings 

Weiss et al. [1999] 

Cat1B_Struct#1_16Test.xls 

B-C drifts, X-1 

17.8 ft wide by

6.4 ft high by

4 ft thick 

Explosion tests 

Quasi-static

Nonuniform 

4-ft-thick seal similar in concept to Figure 20 with 2 reinforced Gunmesh walls sprayed with approximately

0.5-in-thick coating of MB-500 (4,200-psi compressive strength material) and 1 plane of anchored steel reinforcement bar. Aquablend injected between form walls 

(553-psi compressive strength material). Bolts embedded 24 in into roof/floor/ribs with 24 in extending into entry.

Vertical tie-in bolts between roof and floor bolts. 

347 No damage 27.0 NA A-8 

348 No damage 52.5 NA 

349 No damage 87.7 NA 

350 No damage 4 NA 

351 No damage 0.5 NA A-9 

352, 353 No damage — NA 

354 No damage 35.7 NA 

355 No damage 25.3 NA 

356, 357 No damage — NA 

358 No damage 4.2 NA 359 No damage 35.9 NA A-10 

360 No damage 97.4 NA 

361 No damage 0.5 NA 362 No damage 6.2 NA 363 No damage 10.0 NA A-11 

364 No damage 39.1 NA 

365 No damage 39.6 NA 

366 No damage 25.7 NA 

Category 1B: Structure 2

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Meshblock

Weiss et al. [1999] 

Cat1B_Struct#2_5Test.xls 

B-C drifts, X-2 

18.9 ft wide by

7.4 ft high by

13 in thick

Explosion tests 

Quasi-static

Nonuniform 

12-in-thick seal plus 1-in-thick coating identical to 

Figure 20. Stacked Meshblock baskets secured with bolts 

anchored 24 in into roof/floor/ribs. Sprayed MB-500 material (design 4,200 psi) into Meshblock baskets. 5,460-psi compressive strength after 7-day cure and 6,610 psi after 28-day cure. Seal tested on days 12, 19, 27, 40, and 41. 

347 No damage 36.1 NA A-12 

348 No damage 60.0 NA 

349 No damage 78.7 NA 

350 No damage 4 NA A-13 

351 Destroyed 6 NA 

63 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 1B: Structure 3

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Meshblock

Weiss et al. [1999] 

Cat1B_Struct#3_3Test.xls 

B-C drifts, X-3 

19.1 ft wide by

9 ft high by

13 in thick

Explosion tests 

Quasi-static

Nonuniform 

12-in-thick seal plus 1-in-thick coating identical to 

Figure 20 in an enlarged section (9-ft-high entry). Stacked 

Meshblock baskets secured with bolts anchored 24 in into roof/floor/ribs. Sprayed MB-500 material (design 4,200 

psi) into Meshblock baskets. Designed as a 24-hr seal. 

5,930-psi compressive strength of material after 1 day.

Seal tested 27.5 hr after installation and on days 8 

and 16. 

347 No damage 19.2 NA A-14 

348 No damage 74.1 NA 349 Destroyed 109.1 NA 

Category 1B: Structure 4

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Meshblock

Weiss et al. [1999] 

Cat1B_Struct#4_2Test.xls 

B-C drifts, X-4 

19.6 ft wide by

7.4 ft high by

7 in thick 

Explosion tests 

Quasi-static

Nonuniform 

6-in-thick seal plus 1-in-thick coating similar to Figure 20, but not as thick. Stacked Meshblock baskets secured with bolts anchored 24 in into roof/floor/ribs. Sprayed 

MB-500 material (4,200 psi) into Meshblock baskets. 6,010-psi compressive strength after 7-day cure and 

8,778 psi after 28-day cure. Seal tested on days 11 

and 18. 

347 No damage 25.0 NA A-15 348 Destroyed 76.1 NA 

Category 1B: Structure 5

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Gunmesh

Weiss et al. [1999] 

Cat1B_Struct#5_2Test.xls 

B-C drifts, X-5 

19 ft wide by

7.3 ft high by

3 in thick 

Explosion tests 

Quasi-static

Nonuniform 

3-in-thick stopping similar to Figure 20, but not as thick. 

Stacked Meshblock baskets secured with bolts anchored 

24 in into roof/floor/ribs. Sprayed with Tecrete to 3-in

thickness. 5,417-psi compressive strength after 7-daycure and 7,330 psi after 28-day cure. Stopping tested on days 13 and 20. 

347 No damage 18.7 NA A-16 348 Destroyed 59.4 NA 

64 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 1B: Structure 6

Pumped concretelike materials 

with reinforcement 

R. G. Johnson Co., Inc.

Gunmesh

Weiss et al. [1999] 

Cat1B_Struct#6_2Test.xls 

B-C drifts, X-3 

19.3 ft wide by

6.9 ft high by

1.75 in thick

Explosion tests 

Quasi-static

Nonuniform 

1.75-in-thick stopping similar to Figure 20, but not as 

thick. Constructed with reinforced Gunmesh screens and 

sprayed with MB-500 (4,200 psi) and Tecrete. Anchored

with bolts embedded 24 in into roof/floor/ribs with 24 in 

extending into entry. Vertical tie-in reinforcing bars between roof and floor bolts. No samples taken for 

compressive strength testing. Stopping tested on days 7 

and 8. 

350 No damage 3 NA A-17 351 Destroyed 6 NA 

CATEGORY 2A SEALS 

Pumpable cementitious materials with no steel reinforcement and no hitching and with and without carbon fiber retrofit 

Compressive strength of 200 psi and greater than 48 in thick, 4 structures tested 

Category 2A: Structure 1

Pumpable cementitious material 

with Blastseal

Seal retrofit by Transco Mine 

Services Co.

Weiss and Harteis [2008] 

Cat2A_ Struct#1_2Test.xls 

C drift at 320 ft

from closed end

18.7 ft wide by

7.3 ft high by

5.1 ft thick 

Explosion tests 

Reflected 

Uniform 

A 4-ft-thick pumpable cementitious seal similar to Figure 23. Celuseal material was used with a 100- to 

190-psi (143-psi average) compressive strength at 

36 days. A 13-in-thick retrofit structure using a solidconcrete-block wall, polyurethane, carbon fiber-reinforced polymer, and heavy steel angle iron reinforcement across 

the roof and floor was installed against the pumpable seal on the nonexplosion side. 

508 No damage 66 0.60 A-18 

509 Destroyed 195.5 >5.77 A-19 

Category 2A: Structure 2

Pumpable cementitious material 

seal

R. G. Johnson Co., Inc.

Sapko et al. [2005] 

Cat2A_Struct#2_1Test.xls 

Small hydrostatic 

test chamber

21.2 ft wide by

8.7 ft high by

4 ft thick 

Methane ignition

test

Quasi-static

Uniform 

4-ft-thick pumpable cementitious foam seal similar to Figure 23. 350-psi ±75-psi compressive strength. Methane ignition test. 

C3-44E Destroyed 32 >3 A-20 

65 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 2A: Structure 3

Pumpable cementitious material 

seal

R. G. Johnson Co., Inc.

Sapko et al. [2005] 

Cat2A_Struct#3_3Test.xls 

Small hydrostatic 

test chamber

21.2 ft wide by

8.7 ft high by

4 ft thick 

Water tests

Quasi-static

Uniform 

4-ft-thick pumpable cementitious foam seal similar to Figure 23. 350-psi ±75-psi compressive strength. Hydrostatic test. 

C7-64W No damage 21 0.35 A-21

C7-68W No damage 30.5 1.0 A-22 C7-70W No damage 25 0.65 A-23

Category 2A: Structure 4

Pumpable cementitious material 

seal

R. G. Johnson Co., Inc.

Sapko et al. [2005] 

Cat2A_Struct#4_1Test.xls 

Large hydrostatic 

test chamber

30.8 ft wide by

15.6 ft high by

4 ft thick 

Methane ignition

test

Quasi-static

Uniform 

4-ft-thick pumpable cementitious foam seal similar to Figure 23. 350-psi ±75-psi compressive strength. Methane ignition test. 

L2-51E Destroyed 27.5 >3 A-24 

CATEGORY 2B SEALS 

Pumpable cementitious materials with no steel reinforcement and no hitching

Compressive strength of 433 psi and greater than 36 in thick, 1 structure tested 

Category 2B: Structure 1

Pumpable cementitious material 

>36 in

HeiTech Corp. 

Ribfill

Weiss et al. [2002] 

Cat2B_ Struct#1_2Test.xls 

B-C drifts, X-3 

19.4 ft wide by

6.9 ft high by

36 in thick

Explosion tests 

Quasi-static

Nonuniform 

36-in-thick pumpable seal similar to Figure 23. 

Approximate compressive strength of 450–500 psi. 

354 No damage 37.9 NA A-25 355 No damage 32.5 NA 

66 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 2C SEALS 

Pumpable cementitious materials with no steel reinforcement and no hitching

Compressive strength of 480–600 psi and 24–30 in thick, 4 structures tested 

Category 2C: Structure 1 

Pumpable cementitious material 

24–30 in

HeiTech Corp. 

Hydrocrete seal 

Weiss et al. [2002] 

Cat2C_Struct#1_2Test.xls 

B-C drifts, X-2 

19.4 ft wide by

6.9 ft high by

34 in thick

Explosion tests 

Quasi-static

Nonuniform 

34-in-thick Hydrocrete/aggregate seal similar to Figure 23. 

7/8-in-thick reinforcement rods were equally spaced along ribs (2 each), floor (3), and roof (3). These bolts were 

grouted about 3 ft into strata with 3 ft extending into 

crosscut. Wood posts, cross boards, brattice, and wire screen used as forms. The aggregate was dry, crushed limestone aggregate ranging in size from 0.25 to 1 in. Compressive strength test results ranged from 600 to 

840 psi. 

354 No damage 36.0 NA A-26 355 No damage 38.2 NA 

Category 2C: Structure 2 

Pumpable cementitious material 

24–30 in

HeiTech Corp. Hydroseal 

Weiss et al. [2002] 

Cat2C_ Struct#2_2Test.xls 

B-C drifts, X-4 

19 ft wide by

7.55 ft high

by 30 in thick 

Explosion tests 

Quasi-static

Nonuniform 

30-in-thick pumpable seal similar to Figure 23. Formwork 

consisted of wood posts, cross boards, brattice, and wire screen. Injected slurry (Hydroseal) between form walls. Compressive strength tests results ranged from 390 to 

565 psi. 

354 No damage 30.1 NA A-27 355 No damage 28.5 NA 

Category 2C: Structure 3 

Pumpable cementitious material 

24–30 in

HeiTech Corp. Hydroseal 

Weiss et al. [2002] 

Cat2C_Struct#3_2Test.xls 

B-C drifts, X-5 

19.7 ft wide by

7.22 ft high by

24 in thick

Explosion tests 

Quasi-static

Nonuniform 

24-in-thick pumpable seal similar to Figure 23. Formwork consisted of wood posts, cross boards, brattice, and wire screen. Injected slurry (Hydroseal) between form walls. Compressive strength test results ranged from 600 to 

750 psi. 

354 No damage 30.1 NA A-28 

355 No damage 28.5 NA 

67 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 2C: Structure 4 

Pumpable cementitious material 

24–30 in

HeiTech Corp. rapid-construction

column bag pumpable seal 

Weiss et al. [2002] 

Cat2C_ Struct#4_4Test.xls 

B-C drifts, X-2 

19 ft wide by

6.75 ft high by

30 in thick

Explosion tests 

Quasi-static

Nonuniform 

30-in-thick HeiTech grout column seal consisting of six30-in-diam reinforced brattice bag columns spaced across the crosscut with 8- to 18-in gaps between bags and ribs. 

Bags were filled with 600- to 800-psi compressive strength pumpable cementitious slurry, which hardens within 10 min and is nearly fully cured in 24 hr. Similar bags without the reinforcement were then installed 

between the columns and filled with the same grout. 597-psi ±63-psi compressive strength after 13 days. Test 1 conducted 10 days after construction. No hitching. 

Polyurethane foam (Silent Seal) was sprayed around the 

seal perimeter and between the columns from the B-drift side. 

403 No damage 20.8 1.14 A-29 404 No damage 28.7 2.14 A-30 405 No damage 26.7 0.11 A-31 406 Damaged 35.4 >3.2 A-32 

CATEGORY 3A SEALS 

Articulated structures: Solid and hollow-core concrete blocks with or without hitching 

Standard solid-concrete-block seal with hitching, 7 structures tested 

Category 3A: Structure 1

Standard seal with hitching 

NIOSH constructed 

Sapko et al. [2005] 

Cat3A_Struct#1_4Test.xls 

B-C drifts, X-1 

18.3 ft wide by

6.7 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal without pilaster similar 

to Figure 26. Simulated rib and floor hitching with 6-in by6-in by 0.5-in-thick steel angle anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolt III. Fully mortared and staggered joints. 

403 No damage 18.1 0.00 A-33 404 No damage 22.4 0.00 A-34 405 No damage 28.3 0.00 A-35 406 No damage 30.8 0.10 A-36 

68 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 3A: Structure 2

Standard seal with hitching 

NIOSH constructed 

Not previously reported by

NIOSH

Cat3A_Struct#2_10Test.xls 

B-C drifts, X-1 

18.3 ft wide by

6.7 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal with 16-in-wide by

32-in-thick center pilaster identical to Figure 26. Simulated 

rib and floor hitching with 6-in by 6-in by 0.5-in-thick steel 

angle anchored on 18-in centers using 1-in-diam by 9-inlong Hilti Kwik Bolt III. Quikrete BlocBond (1225-51) was 

used as mortar. 

500 No damage 23 NA A-37 

501 No damage 22 NA 

502 No damage 22 NA 

503 No damage 15 NA 

504 No damage 16 NA 

505 No damage 24 NA 

506 No damage 34 NA A-38 

507 No damage 24 NA 

508 No damage 22 NA 

509 No damage 46 NA 

Category 3A: Structure 3

Standard seal with hitching 

NIOSH constructed 

Not previously reported by

NIOSH

Cat3A_Struct#3_2Test.xls 

B-C drifts, X-3 

18.6 ft wide by

6.8 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal with 16-in-wide by

32-in-thick center pilaster identical to Figure 26. Used Type S mortar and B-bond face coatings. Simulated rib 

and floor hitching with 6-in by 6-in by 0.5-in-thick steel 

angle anchored on 18-in centers using 1-in-diam by9-in-long Hilti Kwik Bolt III. 

506 No damage 63 0.11 A-39 

507 No damage 30 0.07 A-40 

Category 3A: Structure 4

Standard seal with hitching 

NIOSH constructed 

Sapko et al. [2005] 

Cat3A_Struct#4_5Test.xls 

Small hydrostatic 

test chamber

16.8 ft wide by

8.6 ft high by

16 in thick

Methane ignition

tests

Quasi-static

Uniform 

Standard solid-concrete-block seal identical to Figure 26. 

2,500 psi (±100-psi) concrete blocks. 16-in-wide by 32-inthick pilaster. Simulated rib and floor hitching with 6-in by

6-in by 0.5-in-thick steel angle anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolt III. Methane 

ignition tests. 

C1-5E No damage 56.5 0.13 A-41 C1-8E No damage 90.1 NA A-42 

C1-9E No damage 94.3 0.22 A-43 

C1-10E No damage 79.5 0.21 A-44 C1-11E Destroyed 99.7 >2.8 A-45 

69 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 3A: Structure 5

Standard seal with hitching 

NIOSH constructed 

Sapko et al. [2005] 

Cat3A_Struct#5_2Test.xls 

Small hydrostatic 

test chamber

16.8 ft wide by

8.6 ft high by

16 in thick

Water and

methane ignition

tests

Quasi-static

Uniform 

Standard solid-concrete-block seal identical to Figure 26. 

2,500-psi (±100-psi) concrete blocks. 16-in-wide by 32-inthick pilaster. Simulated rib and floor hitching with 6-in by

6-in by 0.5-in-thick steel angle anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolt III. Methane 

ignition and hydrostatic tests. 

C6-60W No damage 32 0.024 A-46 

C6-62E No damage 88 0.25 A-47 

Category 3A: Structure 6

Standard seal with hitching 

NIOSH constructed 

Sapko et al. [2005] 

Cat3A_Struct#6_1Test.xls 

Large hydrostatic 

test chamber

28 ft wide by

15.5 ft high by

16 in thick

Methane ignition

test

Quasi-static

Uniform 

Standard solid-concrete-block seal identical to Figure 26. 

2,500-psi (±100-psi) concrete blocks. 16-in-wide by 32-inthick pilaster. Simulated rib and floor hitching with 6-in by

6-in by 0.5-in-thick steel angle anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolt III. Methane 

ignition test. 

L1-37E Destroyed 32 >3 A-48 

Category 3A: Structure 7

Standard seal with hitching 

NIOSH constructed 

Sapko et al. [2005] 

Cat3A_Struct#7_1Test.xls 

SRCM hydrostatic 

test chamber

18 ft wide by

6.2 ft high by

16 in thick

Water test

Quasi-static

Uniform 

Standard solid-concrete-block seal identical to Figure 26. 

1,900- to 2,500-psi (±100-psi) concrete blocks. 16-in-wide by 32-in-thick pilaster. Simulated rib and floor hitching 

with 6-in by 6-in by 0.5-in-thick steel angle anchored on 18-in centers using 1-in-diam by 9-in-long Hilti Kwik Bolt III. Hydrostatic test. 

SRCM-1 Destroyed 20 0.15 A-49 

70 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 3B SEALS 

Articulated structures: Solid and hollow-core concrete blocks with or without hitching 

Solid-concrete-block seal with Packsetter Bags and without hitching, 3 structures tested 

Category 3B: Structure 1

Standard seal with grout bags 

Strata Mine Services Packsetter 

seals

Weiss et al. [2002] 

Cat3B_Struct#1_2Test.xls 

B-C drifts, X-2 

19 ft wide by

6.9 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal similar to Figure 30 

with center pilaster and floor hitching simulated by steel 

angle. Used tongue-and-groove, 8-in solid blocks with 

fully mortared joints and face coatings. Packsetter Bags from Strata Products used on roof and ribs to eliminate need for rib hitching in friable rib conditions. Packsetter Bags pressured to 44 psi. Compressive strength of grout 

in bags is 360 psi after 1 day, 435 psi after 7 days, and 580 psi after 28 days. 

365 No damage 33.9 NA A-50 366 No damage — NA 

Category 3B: Structure 2

Standard seal with grout bags 

Strata Mine Services Packsetter 

seals

Weiss et al. [2002] 

Cat3B_Struct#2_2Test.xls 

B-C drifts, X-3 

19.4 ft wide by

6.9 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal identical to Figure 30

with center pilaster. No floor hitching simulated by steel 

angle. Used tongue-and-groove, 8-in solid blocks with fully mortared joints and face coatings. Packsetter Bags from Strata Products used on roof and ribs to eliminate need for rib hitching in friable rib conditions. Packsetter Bags pressured to 36–40 psi. Compressive strength of grout in bags is 360 psi after 1 day, 435 psi after 7 days, and 580 psi after 28 days. 

365 No damage 49.5 NA A-51 366 No damage 40.4 NA 

Category 3B: Structure 3

Standard seal with grout bags 

Strata Mine Services Packsetter 

seals

Weiss et al. [2002] 

Cat3B_ Struct#3_2Test.xls 

B-C drifts, X-4 

19 ft wide by

7.2 ft high by

16 in thick

Explosion tests 

Quasi-static

Nonuniform 

Standard solid-concrete-block seal with center pilaster 

similar to Figure 30. No floor hitching simulated by steel angle. Used tongue-and-groove, 8-in solid blocks that were dry-stacked with face coatings. Packsetter Bags 

from Strata Products used on roof and ribs to eliminate need for rib hitching in friable rib conditions. Packsetter Bags pressured to 44 psi. Compressive strength of grout 

in bags is 360 psi after 1 day, 435 psi after 7 days, and 580 psi after 28 days. 

365 No damage 31.7 NA A-52 366 Destroyed 41.6 NA 

71 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 3C SEALS 

Articulated structures: Solid and hollow-core concrete blocks with or without hitching 

Ventilation stoppings: Solid and hollow-core concrete blocks without hitching, 8 structures tested 

Category 3C: Structure 1 

Ventilation stopping: 

Hollow-core concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#1_2Test.xls 

B-C drifts, X-4 

18.9 ft wide by

7.1 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, hollow-core concrete block 

stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut 

toward B-drift. Mortar used to level the first block course. 

3-core, concrete block with nominal dimensions of 6 in by

8 in by 16 in and 1,000-psi compressive strength. Wood 

wedges used to tighten each course at the ribs and wood header boards and wedges were used across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant (No. 1227-50; MSHA 

IC 36) applied to both faces of each stopping. 

427 No damage 0.60 0.00 A-53 428 Destroyed 4.0 >3.5 A-54 

Category 3C: Structure 2 

Ventilation stopping: 

Hollow-core concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#2_2Test.xls 

B-C drifts, X-5 

18.8 ft wide by

7.3 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, hollow-core concrete block 

stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut 

toward B-drift. Mortar used to level the first block course. 

3-core, concrete block with nominal dimensions of 6 in by

8 in by 16 in and 1,000-psi compressive strength. Wood 

wedges used to tighten each course at the ribs and wood header boards and wedges were used across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant (No. 1227-50; MSHA 

IC 36) applied to both faces of each stopping. 

427 No damage 0.60 0.00 A-55 428 Destroyed 4.0 >3.5 A-56 

72 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 3C: Structure 3 

Ventilation stopping: 

Hollow-core concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#3_6Test.xls 

B-C drifts, X-6 

17.2 ft wide by

7.1 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, hollow-core concrete block 

stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut 

toward B-drift. Mortar used to level the first block course. 

3-core, concrete block with nominal dimensions of 6 in by

8 in by 16 in with 1,000-psi compressive strength. Wood 

wedges used to tighten each course at the ribs and wood header boards and wedges were used across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant (No. 1227-50; MSHA 

IC 36) applied to both faces of each stopping. 

427 No damage 0.50 0.00 A-57 428 No damage 3.2 0.01 A-58 429 No damage 1.2 0.15 A-59 430 Damaged 3.2 1.0 A-60 432 Damaged 1.8 1.5 A-61 433 Destroyed 3.2 >4.0 A-62 

Category 3C: Structure 4 

Ventilation stopping: 

Hollow-core concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#4_7Test.xls 

B-C drifts, X-7 

16.8 ft wide by

7.3 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, hollow-core concrete block 

stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut 

toward B-drift. Mortar used to level the first block course. 

3-core, concrete block with nominal dimensions of 6 in by

8 in by 16 in with 1,000-psi compressive strength. Wood 

wedges used to tighten each course at the ribs and wood header boards and wedges were used across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant (No. 1227-50; MSHA IC 36) applied to both faces of each stopping. 

427 No damage 0.6 0.04 A-63 428 No damage 3.5 0.19 A-64 429 No damage 1.0 0.13 A-65 430 No damage 2.6 0.34 A-66 432 No damage 1.5 0.43 A-67 433 No damage 3.0 0.68 A-68 434 Damaged 2.5 0.93 A-69 

Category 3C: Structure 5 

Ventilation stopping: 

Solid concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#5_6Test.xls 

B-C drifts, X-4 

18.9 ft wide by

7.1 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, solid-concrete-block stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut toward B-drift. Mortar used to level the first block course. Standard solid concrete block with nominal dimensions of 6 in 

by 8 in by 16 in and 1,300- to 1,740-psi compressive 

strength. Wood wedges used to tighten each course at the ribs and wood header boards and wedges were used 

across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant 

(No. 1227-50; MSHA IC 36) applied to both faces of each stopping. 

457 No damage 0.80 0.00 A-70 458 No damage 1.60 0.06 A-71 459 No damage 4.7 0.67 A-72 460 Damaged 7.5 1.15 A-73 461 Damaged 4.2 0.60 A-74 462 Destroyed 7.7 >3.00 A-75 

73 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 3C: Structure 6 

Ventilation stopping: 

Solid concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#6_7Test.xls 

B-C drifts, X-5 

18.8 ft wide by

7.3 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

Dry-stacked, staggered-joint, solid-concrete-block stopping identical to Figure 32 on small concrete foundation located about 5 ft from the center of the crosscut toward B-drift. Mortar used to level the first block course. Standard solid concrete block with nominal dimensions of 6 in 

by 8 in by 16 in and 1,300- to 1,740-psi compressive 

strength). Wood wedges used to tighten each course at 

the ribs and wood header boards and wedges were used 

across the interface of the top course to the mine roof to tighten the stopping. Quikrete BlocBond sealant 

(No. 1227-50; MSHA IC 36) applied to both faces of each stopping. 

457 No damage 0.75 0.00 A-76 458 No damage 1.4 0.05 A-77 459 No damage 3.7 0.41 A-78 460 No damage 5.4 0.76 A-79 461 No damage 3.9 0.32 A-80 462 No damage 6.7 0.93 A-81 463 Destroyed 19.5 >3.2 A-82 

Category 3C: Structure 7 

Ventilation stopping: 

Solid concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#7_10Test.xls 

A-B drifts, X-6 

19.1 ft wide by

7.6 ft high by

8 in thick 

Explosion tests 

Quasi-static

Nonuniform 

8-in-thick, solid-concrete-block stopping identical to 

Figure 32 with fully mortared (Type S) joints. Quikrete 

B-Bond (No. 1227-50) applied 0.25 in thick on A-drift face. This stopping is located approximately 10 ft into the crosscut as measured from the A-drift rib line. 

510 No damage 16.8 NA A-83 511 No damage 12.1 NA 512 No damage 12.2 NA 513 No damage 11.3 NA A-84 514 No damage 18.1 NA 515 No damage 14.8 NA 516 No damage 19.6 NA A-85 

517 No damage 16.1 NA 518 No damage 13.7 NA 519 No damage 41.1 NA 

Category 3C: Structure 8 

Ventilation stopping: 

Solid concrete block 

NIOSH constructed 

Weiss et al. [2008] 

Cat3C_Struct#8_10Test.xls 

A-B drifts, X-7 

19.5 ft wide by

7.4 ft high by

6 in thick 

Explosion tests 

Quasi-static

Nonuniform 

6-in-thick, solid-concrete-block stopping identical to 

Figure 32 with fully mortared (Type S) joints. Quikrete 

B-Bond (No. 1227-50) applied 0.25 in thick on A-drift face. This stopping is located approximately 10 ft into the crosscut as measured from the A-drift rib line. 

510 No damage 19.1 0.51 A-86 511 No damage 11.0 0.41 A-87 512 No damage 11.2 0.45 A-88 513 No damage 11.3 0.47 A-89 514 No damage 12.2 0.54 A-90 515 No damage 17.5 0.72 A-91 516 No damage 14.4 0.68 A-92 517 No damage 15.3 0.74 A-93 

518 No damage 12.0 0.74 A-94 519 Destroyed 28.8 2.76 A-95 

74 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 4 SEAL 

Polymer and aggregate materials without hitching, 1 structure tested 

Category 4: Structure 1

Polyurethane foam and 

aggregate seal

NIOSH constructed 

Not previously reported by

NIOSH

Cat4_Struct#1_1Test.xls 

Small hydrostatic 

test chamber

20.4 ft wide by

9 ft high by

11 in thick

Methane ignition

test

Quasi-static

Uniform 

Polyurethane foam and aggregate seal similar toFigure 35. 

C8 Destroyed 19 0.5 A-96,

A-97,A-98,

A-99 

CATEGORY 5A SEALS 

Wood-crib-block seals with or without hitching 

Wood-crib-block seal with hitching, 0 structures tested 

Category 5A 

Wood-crib-block seal 

with hitching 

— No tests reported here.

See Figure 38 for typical plan. 

— — — — —

75 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

CATEGORY 5B SEALS 

Wood-crib-block seals with or without hitching 

Wood-crib-block seal with glue and Packsetter Bags, 1 structure tested 

Category 5B: Structure 1

Wood-crib-block seal with glue 

and Packsetter Bags Strata Mine Services 

wood block seal with 

Packsetter Bags

Sapko et al. [2003] 

Cat5B_Struct#1_2Test.xls 

B-C drifts, X-1 

18.4 ft wide by

6.5 ft high by

30 in thick

Explosion tests 

Quasi-static

Nonuniform 

30-in-thick seal identical to Figure 41 using 5-in by 6-in by

30-in-long Eastern Oak crib blocks. The wood blocks 

were installed on a level concrete pad lengthwise parallel with the crosscut ribs. Alternating courses with the 5- or 

6-in dimensions of the crib in the vertical dimension to 

achieve a staggered joint pattern. Approximately

36–40 blocks per course, 14 courses high and about 550 blocks total. 3 beads of adhesive applied between the blocks and block courses. 12 Packsetter Bags installed and injected with grout to about 60 psi along the mine roof and ribs. Compressive strength of grout in bags is 360 psi after 1 day, 435 psi after 7 days, and 580 psi after 28 days. Hitching along the floor and ribs was not used. Polyurethane foam was injected into the gaps between the Packsetter Bags and the mine strata/block interface. 

Each side was spray-coated with Eagle sealant; brattice 

curtain was installed across the B-drift face and sprayed 

with the sealant. Tested 14 days after construction. 

396 No damage 23.2 0.79 A-100 399 No damage 32.4 1.9 A-101 

CATEGORY 6A SEALS 

Articulated structures: Lightweight blocks with or without hitching 

Lightweight blocks: 24 in thick with hitching, 2 structures tested 

Category 6A: Structure 1

Omega blocks

with hitching 

Burrell Mining Products 

Omega block seal 

Cashdollar et al. [2007] 

Cat6A_Struct#1_2Test.xls 

B-C drifts, X-3 

18.8 ft wide by

6.75 ft high by

24 in thick

Explosion tests 

Quasi-static

Nonuniform 

24-in-thick Omega block seal identical to Figure 44 with 

fully mortared joints (Quikrete BlocBond), a 48-in by48-in interlocked center pilaster, and simulated hitch into 

the ribs and floor with 6-in by 6-in by 0.5-in-thick steel 

angle bolted to the ribs and floor. 

508 No damage 52.9 0.04 A-102 509 Damaged 70 2.2 A-103

76 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 6A: Structure 2

Omega blocks

with hitching 

Burrell Mining Products 

Omega block seal 

Sapko et al. [2005] 

Cat6A_Struct#2_1Test.xls 

Small hydrostatic 

test chamber

20 ft wide by

8.2 ft high by

24 in thick

Methane ignition

test

Quasi-static

Uniform 

Properly constructed, Omega block seal identical to Figure 44 with fully mortared joints (Quikrete BlocBond), 

a 48-in by 48-in interlocked center pilaster, and simulated hitch into the ribs and floor with 6-in by 6-in by 0.5-in-thick steel angle bolted to the ribs and floor. 100-psi ±20-psi compressive strength. Methane ignition test. 

C4-48E Destroyed 22 >3 A-104 

CATEGORY 6B SEALS 

Articulated structures: Lightweight blocks with or without hitching 

Lightweight blocks: 40 in thick without hitching, 8 structures tested 

Category 6B: Structure 1

Omega blocks, 

no hitching

Burrell Mining Products 

rapid-design Omega block seal

Sapko et al. [2003] 

Cat6B_Struct#1_4Test.xls 

B-C drifts, X-3 

19 ft wide by

6.75 ft high by

40 in thick

Explosion tests 

Quasi-static

Nonuniform 

Burrell’s 40-in-thick Omega 384 block seal identical to Figure 48 with fully mortared and staggered joints and full 

face coatings using Quikrete BlocBond. Rough-cut lumber was used across the top of the seal and then wedged tightly at the mine roof. No hitching. 

403 No damage 23.4 0.29 A-105 404 No damage 29.7 0.49 A-106 405 No damage 30.2 0.06 A-107 406 No damage 31.2 0.78 A-108 

Category 6B: Structure 2

Omega blocks, 

no hitching

Burrell Mining Products 

Omega block seal 

Cashdollar et al. [2007] 

Cat6B_Struct#2_9Test.xls 

B-C drifts, X-2 

18.8 ft wide by

6.7 ft high by

40 in thick

Explosion tests 

Quasi-static

Nonuniform 

Properly built, 40-in-thick Omega block seal identical to Figure 48 as built by Burrell with fully mortared and 

staggered joints and full face coatings using Quikrete BlocBond. Fully mortared at top of seal. No hitching. 

501 No damage 24.8 0.04 A-109 502 No damage 23.4 0.03 A-110 503 No damage 13.3 0.01 A-111 504 No damage 15.1 0.01 A-112 505 No damage 38.8 0.03 A-113 506 No damage 67.6 0.08 A-114 507 No damage 29.7 0.055 A-115 

508 No damage 29.1 NA A-116 

509 No damage 118.4 NA 

77 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 6B: Structure 3

Omega blocks, 

no hitching

Hybrid Omega block seal 

Cashdollar et al. [2007] 

Cat6B_Struct#3_2Test.xls 

B-C drifts, X-3 

18.8 ft wide by

6.75 ft high by

40 in thick

Explosion tests 

Quasi-static

Nonuniform 

Hybrid 40-in-thick Omega block seal similar to Figure 48. Dry layer of BlocBond applied to floor, then dampened before installing first block course. BlocBond was applied 

to top of first course and forced into vertical joints by

hand; other courses installed in similar manner. Wedgedtight (skin to skin) across top center boards (~18-in gapbetween centered board ends and each rib); attempts by

hand to fill all gaps with BlocBond. 

501 No damage 28.5 0.13 A-117 502 Destroyed 51.1 >5.8 A-118 

Category 6B: Structure 4

Omega blocks, 

no hitching

Omega block seal 

as built at Sago Mine

Cashdollar et al. [2007] 

Cat6B_Struct#4_3Test.xls 

B-C drifts, X-3 

18.8 ft wide by

6.75 ft high by

40 in thick

Explosion tests 

Quasi-static

Nonuniform 

Hybrid 40-in-thick Omega block seal similar to Figure 48. Dry layer of BlocBond applied to floor, then dampened before installing first block course. BlocBond was applied 

to top of first course and forced into vertical joints by

hand; other courses installed in similar manner. Wedgedtight (skin to skin) across top rib-to-rib boards; attempts byhand to fill all gaps with BlocBond. 

503 No damage 16.0 0.04 A-119 504 No damage 18.4 0.085 A-120 

505 Destroyed 42.4 >5.4 A-121 

Category 6B: Structure 5

Omega blocks, 

no hitching

Burrell Mining Products 

Omega block seal 

Cashdollar et al. [2007] 

Cat6B_Struct#5_1Test.xls 

C drift at 320 ft

18.7 ft wide by

7.3 ft high by

41 in thick

Explosion test 

Reflected 

Uniform 

Properly built, 40-in-thick Omega block seal identical to Figure 48 with staggered and fully mortared joints using 

BlocBond. Wedged tight across entire roof. Wedged tight (skin to skin) across top rib-to-rib boards; attempts byhand to fill all gaps with BlocBond. No hitching. 

502 Destroyed 61 >6.1 A-122 

78 
Table A-1.—Detailed summary of seal structure tests—Continued 

Seal category – Structure No. 

Description 

Manufacturer

NIOSH reference 

Excel data file name 

Seal test location, 

dimensions, 

test type, 

and loading 

conditions 

Seal description from LLEM test files 

LLEM

test

No. 

Test

outcome 

Maximum 

pressure

data(psi) 

Maximum 

displacement

data

(in) 

Appendix

figure

No. 

Category 6B: Structure 6

Omega blocks, 

no hitching

Omega block seal 

as built at Sago Mine

Cashdollar et al. [2007] 

Cat6B_Struct#6_3Test.xls 

C drift at 320 ft

18.7 ft wide by

7.3 ft high by

40 in thick

Explosion tests 

Reflected 

Uniform 

Hybrid 40-in-thick Omega block seal similar to Figure 48. Dry layer of BlocBond applied to floor, then dampened before installing first block course. BlocBond was applied 

to top of first course and forced into vertical joints by

hand; other courses installed in similar manner. Wedgedtight (skin to skin) across top rib-to-rib boards; attempts byhand to fill all gaps with BlocBond. 

503 No damage 17.2 0.045 A-123 

504 No damage 20.7 0.065 A-124 

505 Destroyed 63.2 >6.0 A-125 

Category 6B: Structure 7

Omega blocks, 

no hitching

Omega block seal 

as built at Sago Mine

using blocks from Sago 

Cashdollar et al. [2007] 

Cat6B_Struct#7_1Test.xls 

C drift at 320 ft

18.7 ft wide by

7.3 ft high by

40 in thick

Explosion test 

Reflected 

Uniform 

Hybrid 40-in-thick Omega block seal similar to Figure 48. Dry layer of BlocBond applied to floor, then dampened before installing first block course. BlocBond was applied 

to top of first course and forced into vertical joints by

hand; other courses installed in similar manner. Wedgedtight (skin to skin) across top rib-to-rib boards; attempts byhand to fill all gaps with BlocBond. 

506 Destroyed 118.2 >6.2 A-126 

Category 6B: Structure 8

Omega blocks, 

no hitching

Burrell Mining Products 

rapid-design Omega block Seal

Sapko et al. [2005] 

Cat6B_Struct#8_1Test.xls 

Small hydrostatic 

test chamber

20.6 ft wide by

8.8 ft high by

40 in thick

Methane ignition

test

Quasi-static

Uniform 

Omega block seal identical to Figure 48. 

100-psi ±20-psi compressive strength. 

C5-53E Destroyed 22.5 >3 A-127 

NA Not available. 

79 
50 2 

45 1.8 

Pressure - static, nonuniform loading 

Displacement 

40 1.6 

pressure - psi 

displacement - inches 

35 

30 

25 

20 

15 

10 

5 

0 

1.4 

1.2 

1 

0.8 

0.6 

0.4 

0.2 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-1.—Category 1A - structure #1 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #419. 

50 4

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

45 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

displacement - inches 

pressure - psi 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-2.—Category 1A - structure #2 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #419. 

80 
45 

3.5 

50 4 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

3 

2.5 

2 

1.5 

1 

0.5 

0 

pressure - psi 

displacement - inches 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-3.—Category 1A - structure #3 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #419. 

pressure - psi

displacement - inches 

60 

50 

40 

30 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 

0.05 

0.1 

0.09 

0.08 

0.07 

0.06 

0.04 

20 

0.03 

0.02 

10 

0.01 

0 0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-4.—Category 1A - structure #4 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #420. 

81 
0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

pressure - psi 

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

displacement - inches 

Pressure - static, nonuniform loading 

Displacement 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-5.—Category 1A - structure #5 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #420. 

45 

50 0.1 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-6— Category 1A - structure #6 - test 1 - static, nonuniform loading.
 

Insteel 3-D seal - shotcrete with reinforcement - LLEM test #420. 

0.09 

82 
pressure - psi 

35 0.25 

25 

30 

Pressure - static, uniform loading 

Displacement 0.20 

20 

0.15 

15 

0.10 

5 

10 

0.05 

0 

0 100 200 300 400 

time - seconds 

500 600 700 800 

0.00 

Figure A-7.—Category 1A - structure #7 - test 1 - static, uniform loading. 

Insteel 3-D seal - shotcrete with reinforcement - PR-1. 

displacement - inches 

 

 

 

 

pressure - psi 

100 

60 

70 

80 

90 

Pressure - LLEM#347 - static, nonuniform loading 

Pressure - LLEM#348 - static, nonuniform loading 

Pressure - LLEM#349 - static, nonuniform loading 

Pressure - LLEM#350 - static, nonuniform loading 

50 

40 

30 

20 

10 

0 

2.400 2.500 2.600 2.700 2.800 2.900 3.000 3.100 3.200 3.300 3.400 

time - seconds 

Figure A-8.—Category 1B - structure #1 - tests 1 to 4 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #347–350. 

83 
50 

pressure - psi 

45 Pressure - LLEM#351 - static, nonuniform loading 

40 Pressure - LLEM#354 - static, nonuniform loading 

35 Pressure - LLEM#355 - static, nonuniform loading 

30 

Pressure - LLEM#358 - static, nonuniform loading 

25 

20 

15 

10 

5 

0 

0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 

time - seconds 

Figure A-9.—Category 1B - structure #1 - tests 5 to 8 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #351–358. 

pressure - psi 

100 

90 

Pressure - LLEM#359 - static, nonuniform loading 

80 Pressure - LLEM#360 - static, nonuniform loading 

70 Pressure - LLEM#361 - static, nonuniform loading 

Pressure - LLEM#362 - static, nonuniform loading 60 

50 

40 

30 

20 

10 

0 

0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 

time - seconds 

Figure A-10.—Category 1B - structure #1 - tests 9 to 12 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #359–362. 

84 
0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

pressure - psi 

Pressure - LLEM#363 - static, nonuniform loading 

Pressure - LLEM#364 - static, nonuniform loading 

Pressure - LLEM#365 - static, nonuniform loading 

Pressure - LLEM#366 - static, nonuniform loading 

0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 

time - seconds 

Figure A-11.—Category 1B - structure #1 - tests 13 to 16 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #363–366. 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

pressure - psi 

Pressure - LLEM#347 - static, nonuniform loading 

Pressure - LLEM#348 - static, nonuniform loading 

Pressure - LLEM#349 - static, nonuniform loading 

2.400 2.500 2.600 2.700 2.800 2.900 3.000 3.100 3.200 3.300 3.400 

time - seconds 

Figure A-12.—Category 1B - structure #2 - tests 1 to 3 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #347–349. 

85 
0 

1 

2 

3 

4 

5 

6 

7 

8 

pressure - time 

Pressure - LLEM#350 - static, nonuniform loading 

Pressure - LLEM#351 - static, nonuniform loading 

3.000 3.100 3.200 3.300 3.400 3.500 3.600 3.700 3.800 3.900 4.000 

time - seconds 

Figure A-13.—Category 1B - structure #2 - tests 4 and 5 - static, nonuniform loading. 

Meshblock seal - shotcrete with reinforcement - LLEM tests #350–351. 

120 

pressure - psi 

0 

20 

40 

60 

80 

100 

Pressure - LLEM#347 - static, nonuniform loading 

Pressure - LLEM#348 - static, nonuniform loading 

Pressure - LLEM#349 - static, nonuniform loading 

2.700 2.750 2.800 2.850 2.900 2.950 3.000 3.050 3.100 3.150 3.200 

time - seconds 

Figure A-14.—Category 1B - structure #3 - tests 1 to 3 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #347–349. 

86 
0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

pressure - psi 

Pressure - LLEM#347 - static, nonuniform loading 

Pressure - LLEM#348 - static, nonuniform loading 

2.700 2.750 2.800 2.850 2.900 2.950 3.000 3.050 3.100 3.150 3.200 

time - seconds 

Figure A-15.—Category 1B - structure #4 - tests 1 and 2 - static, nonuniform loading.
 

Meshblock seal - shotcrete with reinforcement - LLEM tests #347–348. 

 

 

pressure - psi 

0 

10 

20 

30 

40 

50 

60 

70 

80 

Pressure - LLEM#347 - static, nonuniform loading 

Pressure - LLEM#348 - static, nonuniform loading 

2.700 2.750 2.800 2.850 2.900 2.950 3.000 3.050 3.100 3.150 3.200 

time - seconds 

Figure A-16.—Category 1B - structure #5 - tests 1 and 2. 

Meshblock seal - shotcrete with reinforcement - LLEM tests #347–348. 

87 
pressure - psi 

-1 

-2 

3.000 3.100 3.200 3.300 3.400 3.500 3.600 3.700 3.800 3.900 4.000 

time - seconds 

Pressure - LLEM#350 - static, nonuniform loading 

Pressure - LLEM#350 - static, nonuniform loading 

Figure A-17.—Category 1B - structure #6 - tests 1 and 2 - static, nonuniform loading. 

Meshblock seal - shotcrete with reinforcement - LLEM tests #350–351. 

6 

5 

4 

3 

2 

1 

0 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

pressure - psi 

0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1 

displacement - inches 

Pressure - reflected, uniform loading 

Displacement 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-18.—Category 2A - structure #1 - test 1 - reflected, uniform loading.
 

Pumpable 48 in - LLEM test #508. 

88 
0 

50 

100 

150 

200 

250 

pressure - psi 

0 

1 

2 

3 

4 

5 

6 

displacement - inches 

Pressure - reflected, uniform loading 

Displacement 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-19.—Category 2A - structure #1 - test 2 - reflected, uniform loading.
 

Pumpable 48 in - LLEM test #509. 

0 

5 

10 

15 

20 

25 

30 

35 

pressure - psi 

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

0 5 10 15 20 25 

time - seconds 

Figure A-20.—Category 2A - structure #2 - test 1 - static, uniform loading.
 

Pumpable 48 in - test C3-44E. 

89 
20 0.4 

25 

Pressure - static, uniform loading 

Displacement 

0.5 

0.45 

displacement - inches 

pressure - psi 

15
 

10
 

5
 

0 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

0 200 400 600 800 1000 1200
 

time - seconds 

Figure A-21.—Category 2A - structure #3 - test 1 - static, uniform loading.
 

Pumpable 48 in - test C7-64W. 

35 

pressure - psi 

1.2 

30
 

25
 

20
 

15
 

10
 

5
 

0 

Pressure - static, uniform loading 

Displacement 1
 

0.8 

0.6 

0.4 

0.2 

0 

displacement - inches 

0 200 400 600 800 1000 1200
 

time - seconds 

Figure A-22.—Category 2A - structure #3 - test 2 - static, uniform loading.
 

Pumpable 48 in - test C7-68W. 

90 
10 

pressure - psi 

displacement - inches 

30 

25 

20 

15 

0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

Pressure - static, uniform loading 

Displacement 

0 200 400 600 800 1000 1200 

time - seconds 

5 

0 

Figure A-23.—Category 2A - structure #3 - test 3 - static, uniform loading. 

Pumpable 48 in - test C7-70W. 

0 

5 

10 

15 

20 

25 

30 

pressure - psi 

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

0 0.5 1 1.5 2 2.5

time - seconds 

Figure A-24.—Category 2A - structure # 4 - test 1 - static, uniform loading.
 

Pumpable 48 in - test L2-51E. 

91 
pressure - psi 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - LLEM#354 - static, nonuniform loading 

Pressure - LLEM#355 - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-25.—Category 2B - structure #1 - tests 1 and 2 - static, nonuniform loading.
 

Pumpable 36 in - LLEM tests #354–355. 

pressure - psi 

50 

45 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - LLEM#354 - static, nonuniform loading 

Pressure - LLEM#355 - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-26.—Category 2C - structure #1 - tests 1 and 2 - static, nonuniform loading.
 

Pumpable 24 in - LLEM tests #354–355. 

92 
pressure - psi 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - LLEM#354 - static, nonuniform loading 

Pressure - LLEM#355 - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-27.—Category 2C - structure #2 - tests 1 and 2 - static, nonuniform loading.
 

Pumpable 24 in - LLEM tests #354–355. 

pressure - psi 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - LLEM#354 - static, nonuniform loading 

Pressure - LLEM#355 - static, nonuniform loading 

0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 

time - seconds 

Figure A-28.—Category 2C - structure #3 - tests 1 and 2 - static, nonuniform loading.
 

Pumpable 24 in - LLEM tests #354–355. 

93 
40 4 

35 3.5 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 

time - seconds 

Figure A-29.—Category 2C - structure #4 - test 1 - static, nonuniform loading.
 

Pumpable 24 in - LLEM test #403. 

pressure - psi 

displacement - inches 

40 4 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading Displacement 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 

time - seconds 

Figure A-30.—Category 2C - structure #4 - test 2 - static, nonuniform loading.
 

Pumpable 24 in - LLEM test #404. 

94 
35 3.5 

40 4 

pressure - psi 

displacement - inches 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 

time - seconds 

Figure A-31.—Category 2C - structure #4 - test 3 - static, nonuniform loading.
 

Pumpable 24 in - LLEM test #405. 

pressure - psi 

displacement - inches 

40 4 

35 3.5 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 

time - seconds 

Figure A-32.—Category 2C - structure #4 - test 4 - static, nonuniform loading.
 

Pumpable 24 in - LLEM test #406. 

95 
35 

0.18 

40 0.2 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

pressure - psi 

displacement - inches 

0.350 0.450 0.550 0.650 0.750 0.850 0.950 

time - seconds 

Figure A-33.—Category 3A - structure #1 - test 1 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #403. 

35 

40 

pressure - psi 

displacement - inches 

0.2 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 

0.18 

30 

25 

20 

15 

10 

5 

0 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

0.350 0.450 0.550 0.650 0.750 0.850 0.950 

time - seconds 

Figure A-34.—Category 3A - structure #1 - test 2 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #404. 

96 
0 

5 

10 

15 

20 

25 

30 

35 

40 

pressure - psi 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

0.2 

displacement - inches 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 

0.350 0.450 0.550 0.650 0.750 0.850 0.950 

time - seconds 

Figure A-35.—Category 3A - structure #1 - test 3 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #405. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

pressure - psi 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

0.2 

displacement - inches 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 

0.350 0.450 0.550 0.650 0.750 0.850 0.950 

time - seconds 

Figure A-36.—Category 3A - structure #1 - test 4 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #406. 

97 
-10 

-5 

0 

5 

10 

15 

20 

25 

30 

0.300 0.500 0.700 0.900 1.100 1.300 1.500 1.700 1.900 2.100 2.300 

pressure - psi 

Pressure - LLEM#500 - static, nonuniform loading 

Pressure - LLEM#501 - static, nonuniform loading 

Pressure - LLEM#502 - static, nonuniform loading 

Pressure - LLEM#503 - static, nonuniform loading 

Pressure - LLEM#504 - static, nonuniform loading 

Pressure - LLEM#505 - static, nonuniform loading 

time - seconds 

Figure A-37.—Category 3A - structure #2 - tests 1 to 6 - static, nonuniform loading. 

Standard solid-concrete-block seal - LLEM tests #500–505. 

-30 

-20 

-10 

0 

10 

20 

30 

40 

50 

0.300 0.400 0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 

pressure - psi 

Pressure - LLEM#506 - static, 

nonuniform loading 

Pressure - LLEM#507 - static, 

nonuniform loading 

Pressure - LLEM#508 - static, 

nonuniform loading 

Pressure - LLEM#509 - static, 

nonuniform loading 

time - seconds 

Figure A-38.—Category 3A - structure #2 - tests 7 to 10 - static, nonuniform loading. 

Standard solid-concrete-block seal - LLEM tests #506–509. 

98 
80 0.45 

90 0.5 

70 

60 

50 

40 

30 

20 

10 

0 

0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 1.000 

time - seconds 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 0.4 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

pressure - psi 

displacement - inches 

-10 0 

Figure A-39.—Category 3A - structure #3 - test 1 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #506. 

35 

pressure - psi 

displacement - inches 

40 0.2 

0.18 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 30 

25 

20 

15 

10 

5 

0 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 1.000 

time - seconds 

Figure A-40.—Category 3A - structure #3 - test 2 - static, nonuniform loading.
 

Standard solid-concrete-block seal - LLEM test #507. 

99 
0 

10 

20 

30 

40 

50 

60 

pressure - psi 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

0 5 10 15 20 25 

time - seconds 

Figure A-41.—Category 3A - structure #4 - test 1 - static, uniform loading.
 

Standard solid-concrete-block seal - test C1-5E. 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

pressure - psi 

Pressure - static, uniform loading 

0 5 10 15 20 25 

time - seconds 

Figure A-42.—Category 3A - structure #4 - test 2 - static, uniform loading.
 

Standard solid-concrete-block seal - test C1-8E. 

100 
100 0.25 

90
 

80
 

70
 

60
 

50
 

40
 

30
 

20
 

10
 

0
 

Pressure - static, uniform loading 

Displacement - (noise in data) 

pressure - psi 

displacement - inches 

0.2 

0.15 

0.1 

0.05 

0 

0 5 10 15 20 25
 

time - seconds 

Figure A-43.—Category 3A - structure #4 - test 3 - static, uniform loading.
 

Standard solid-concrete-block seal - test C1-9E. 

pressure - psi 

displacement - inches 

100
 0.25
 

90
 

80
 

70
 

60
 

50
 

40
 

30
 

20
 

10
 

0
 

Pressure - static, uniform loading 

Displacement 

0.2 

0.15 

0.1 

0.05 

0 

0 5 10 15 20 25
 

time - seconds 

Figure A-44.—Category 3A - structure #4 - test 4 - static, uniform loading.
 

Standard solid-concrete-block seal - test C1-10E. 

101 
100
 

Pressure - static, uniform loading 

Displacement 

3 

90
 

2.5 

80
 

70
 2
 

pressure - psi 

displacement - inches 

60
 

50
 

40
 

30
 

20
 

10
 

0
 

1.5 

1
 

0.5 

0 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 

time - seconds 

Figure A-45.—Category 3A - structure #4 - test 5 - static, uniform loading.
 

Standard solid-concrete-block seal - test C1-11E. 

35 

pressure - psi 

displacement - inches 

0.04 

30
 

25
 

20
 

15
 

10
 

5
 

0 

Pressure - static, uniform loading 

Displacement - (noise in data) 

0.035 

0.03 

0.025 

0.02 

0.015 

0.01 

0.005 

0 

0 500 1000 1500 2000 2500 3000 3500 4000 4500
 

time - seconds 

Figure A-46.—Category 3A - structure #5 - test 1 - static, uniform loading.
 

Standard solid-concrete-block seal - test C6-60W. 

102 
6 8 10 12

 - seconds 

ture #5 - test 2 - static, uniform loading.
 

ete-block seal - test C6-62E. 

103 

90 

0.35 

100 0.4 

Pressure - static, uniform loading 

Displacement - (noise in data) 

pressure - psi 

displacement - inches 

80
 

70
 

60
 

50
 

40
 

30
 

20
 

10
 

0
 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

0 2 4

time

Figure A-47.—Category 3A - struc

Standard solid-concr

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

15 20 25 30
 

 - seconds 

ture #6 - test 1 - static, uniform loading.
 

ete-block seal - test L1-37E. 

0 

5 

10 

15 

20 

25 

30 

35 

pressure - psi 

0 5 10

time

Figure A-48.—Category 3A - struc

Standard solid-concr
0 

5 

10 

15 

20 

25 

pressure - psi 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

0.2 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

0 50 100 150 200 250 300
 

time - seconds 

Figure A-49.—Category 3A - structure #7 - test 1 - static, uniform loading.
 

Standard solid-concrete-block seal - test SRCM 1. 

pressure - psi 

0 

5 

10 

15 

20 

25 

30 

35 

40 

Pressure - static, nonuniform loading 

Pressure - static, nonuniform loading 

Pressure - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-50.—Category 3B - structure #1 - test 1 - static, nonuniform loading.
 

Solid-concrete-block seal with Packsetter bags - LLEM test #365. 

104 
0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

pressure -psi 

Pressure - LLEM#365 - static, nonuniform loading 

Pressure - LLEM#366 - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-51.—Category 3B - structure #2 - tests 1 and 2 - static, nonuniform loading.
 

Solid-concrete-block seal with Packsetter bags - LLEM tests #365–366. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

pressure - psi 

Pressure - LLEM#365 - static, nonuniform loading 

Pressure - LLEM#366 - static, nonuniform loading 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-52.—Category 3B - structure #3 - tests 1 and 2 - static, nonuniform loading.
 

Solid-concrete-block seal with Packsetter bags - LLEM tests #365–366. 

105 
1 0.05 

0.9 Pressure - static, nonuniform loading - (noise in data) 0.045 

0.8 Displacement - (noise in data) 0.04 

0.7 0.035 

0.6 0.03 

0.5 0.025 

0.4 0.02 

0.3 0.015 

0.2 0.01 

0.1 0.005 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 

time - seconds 

pressure - psi 

displacement - inches 

Figure A-53.—Category 3C - structure #1 - test 1 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #427. 

pressure - psi 

displacement - inches 

5 5 

4.5 4.5 

4 4 

3.5 3.5 

3 3 

2.5 2.5 

2 2 Pressure - static, nonuniform loading - (noise in data) 

1.5 1.5 Displacement

1 1 

0.5 0.5 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 

time - seconds 

Figure A-54.—Category 3C - structure #1 - test 2 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #428. 

106 
pressure - psi 

displacement - inches 

1 0.05 

0.9 Pressure - static, nonuniform loading - (noise in data) 0.045 

0.8 Displacement - (noise in data) 0.04 

0.7 0.035 

0.6 0.03 

0.5 0.025 

0.4 0.02 

0.3 0.015 

0.2 0.01 

0.1 0.005 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 

time - seconds 

Figure A-55.—Category 3C - structure #2 - test 1 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #427. 

pressure - psi 

displacement - inches 

5 5 

4.5 4.5 

4 4 

3.5 3.5 

3 3 

2.5 2.5 Pressure - static, nonuniform loading - (noise in data) 

2 2 Displacement 

1.5 1.5 

1 1 

0.5 0.5 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 

time - seconds 

Figure A-56.—Category 3C - structure #2 - test 2 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #428. 

107 
pressure - psi 

displacement - inches 

5 0.5 

4.5 Pressure - static, nonuniform loading - (noise in data) 0.45 

4 Displacement - (noise in data) 0.4 

3.5 0.35 

3 0.3 

2.5 0.25 

2 0.2 

1.5 0.15 

1 0.1 

0.5 0.05 

0 0 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-57.—Category 3C - structure #3 - test 1 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #427. 

pressure - psi 

displacement - inches 

5 0.1 

Pressure - static, nonuniform loading - (noise in data) 4.5 0.09 

Displacement - (noise in data) 4 0.08 

3.5 0.07 

3 0.06 

2.5 0.05 

2 0.04 

1.5 0.03 

1 0.02 

0.5 0.01 

0 0 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-58.—Category 3C - structure #3 - test 2 - static, nonuniform loading. 

Hollow-core concrete-block ventilation stopping - LLEM test #428. 

108 
4.5 

5 0.25 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.2 

0.15 

0.1 

0.05 

0 

pressure - psi 

displacement - inches 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-59.—Category 3C - structure #3 - test 3 - static, nonuniform loading.
 

Hollow-core concrete-block ventilation stopping - LLEM test #429.
 

4.5 

pressure - psi 

displacement - inches 

5 2 

Pressure - static, nonuniform loading - (noise in data) 

4 Displacement 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

1.6 

1.4 

1.2 

1 

0.8 

0.6 

0.4 

0.2 

0 

0.500 0.520 0.540 0.560 0.580 0.600 0.620 0.640 0.660 0.680 0.700 

time - seconds 

Figure A-60.—Category 3C - structure #3 - test 4 - static, nonuniform loading.
 

Hollow-core concrete-block ventilation stopping - LLEM test #430.
 

1.8 

109 
4.5 1.8 

5 2 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 1.6 

1.4 

1.2 

1 

0.8 

0.6 

0.4 

0.2 

0 

pressure - psi 

displacement - inches 

0.500 0.520 0.540 0.560 0.580 0.600 0.620 0.640 0.660 0.680 0.700 

time - seconds 

Figure A-61.—Category 3C - structure #3 - test 5 - static, nonuniform loading.
 

Hollow-core concrete-block ventilation stopping - LLEM test #432.
 

4.5 

pressure - psi 

displacement - inches 

5 5 

Pressure - static, nonuniform loading - (noise in data) 

4 Displacement 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.500 0.520 0.540 0.560 0.580 0.600 0.620 0.640 0.660 0.680 0.700 

time - seconds 

Figure A-62.—Category 3C - structure #3 - test 6 - static, nonuniform loading.
 

Hollow-core concrete-block ventilation stopping - LLEM test #433.
 

4.5 

110 
 4.5 0.09 

5 0.1 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-63.—Category 3C - structure #4 - test 1 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #427.
 

4.5 

5 

pressure - psi 

displacement - inches 

0.25 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.2 

0.15 

0.1 

0.05 

0 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-64.—Category 3C - structure #4 - test 2 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #428.
 

111 
4.5 

5 0.25 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.2 

0.15 

0.1 

0.05 

0 

pressure - psi 

displacement - inches 

0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 

time - seconds 

Figure A-65.—Category 3C - structure #4 - test 3 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #429.
 

4.5 

pressure - psi 

displacement - inches 

5 0.5 

Pressure - static, nonuniform loading - (noise in data) 

4 Displacement 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.4 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-66.—Category 3C - structure #4 - test 4 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #430.
 

0.45 

112 
0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

4.5 

5 

pressure - psi 

0 

0.05 

0.1 

0.15 

0.2 

0.25 

0.3 

0.35 

0.4 

0.45 

0.5 

displacement - inches 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 

0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-67.—Category 3C - structure #4 - test 5 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #432.
 

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

4.5 

5 

pressure - psi 

0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1 

displacement - inches 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 

0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-68.—Category 3C - structure #4 - test 6 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #433.
 

113 
pressure - psi 

displacement - inches 

5 1 

Pressure - static, nonuniform loading - (noise in data) 4.5 0.9 

Displacement 4 0.8 

3.5 0.7 

3 0.6 

2.5 0.5 

2 0.4 

1.5 0.3 

1 0.2 

0.5 0.1 

0 0 

0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-69.—Category 3C - structure #4 - test 7 - static, nonuniform load. 

Hollow-core concrete-block ventilation stopping - LLEM test #434. 

pressure - psi 

displacement - inches 

5 0.1 

4.5 Pressure - static, nonuniform loading - (noise in data) 0.09 

4 Displacement - (noise in data) 0.08 

3.5 0.07 

3 0.06 

2.5 0.05 

2 0.04 

1.5 0.03 

1 0.02 

0.5 0.01 

0 0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-70.—Category 3C - structure #5 - test 1 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #457. 

114 
4.5 0.09 

5 0.1 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-71.—Category 3C - structure #5 - test 2 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #458. 

4.5 

pressure - psi 

displacement - inches 

5 1 

Pressure - static, nonuniform loading - (noise in data) 

4 Displacement 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-72.—Category 3C - structure #5 - test 3 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #459. 

0.9 

115 
7 1.75 

8 2 

pressure - psi 

displacement - inches 

6 

5 

4 

3 

2 

1 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 

1.5 

1.25 

1 

0.75 

0.5 

0.25 

0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-73.—Category 3C - structure #5 - test 4 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #460. 

9 

pressure - psi 

displacement - inches 

10 1 

Pressure - static, nonuniform loading - (noise in data) 

8 Displacement 

7 

6 

5 

4 

3 

2 

1 

0 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-74.—Category 3C - structure #5 - test 5 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #461. 

0.9 

116 
pressure - psi 

displacement - inches 

10 5 

9 Pressure - static, nonuniform loading - (noise in data) 4.5 

8 Displacement 4 

7 3.5 

6 3 

5 2.5 

4 2 

3 1.5 

2 1 

1 0.5 

0 0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-75.—Category 3C - structure #5 - test 6 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #462. 

pressure - psi 

displacement - inches 

5 0.1 

4.5 Pressure - static, nonuniform loading - (noise in data) 0.09 

4 Displacement - (noise in data) 0.08 

3.5 0.07 

3 0.06 

2.5 0.05 

2 0.04 

1.5 0.03 

1 0.02 

0.5 0.01 

0 0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-76.—Category 3C - structure #6 - test 1 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #457. 

117 
5 0.1 

4.5 0.09 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-77.—Category 3C - structure #6 - test 2 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #458. 

 

pressure - psi 

displacement - inches 

5 0.5 

4.5 0.45 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement - (noise in data) 

0.4 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-78.—Category 3C - structure #6 - test 3 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #459. 

118 
9 0.9 

10 1 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

pressure - psi 

displacement - inches 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-79.—Category 3C - structure #6 - test 4 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #460. 

8 

pressure - psi 

displacement - inches 

10 1 

9 0.9 

Pressure - static, nonuniform loading - (noise in data) 

Displacement 7 

6 

5 

4 

3 

2 

1 

0 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-80.—Category 3C - structure #6 - test 5 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #461. 

0.8 

119 
9 0.9 

10 1 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Pressure - static, nonuniform loading - (noise in 

data) 

Displacement 0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

pressure - psi 

displacement - inches 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-81.—Category 3C - structure #6 - test 6 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #462. 

pressure - psi 

8 

displacement - inches 

20 

18 

16 

14 

12 

6 

Pressure - static, nonuniform loading -

(noise in data) 

Displacement 

1.2 

4 0.8 

2 0.4 

0 0 

4 

3.6 

3.2 

2.8 

2.4 

10 

1.6 

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 

time - seconds 

Figure A-82.—Category 3C - structure #6 - test 7 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #463. 

2 

120 
0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20 

pressure - psi 

Pressure - LLEM#510 - static, nonuniform loading 

Pressure - LLEM#511 - static, nonuniform loading 

Pressure - LLEM#512 - static, nonuniform loading 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-83.—Category 3C - structure #7 - tests 1 to 3 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM tests #510–512. 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20 

pressure - psi 

Pressure - LLEM#513 - static, nonuniform loading 

Pressure - LLEM#514 - static, nonuniform loading 

Pressure - LLEM#515 - static, nonuniform loading 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-84.—Category 3C - structure #7 - tests 4 to 6 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM tests #513–515. 

121 
0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

pressure - psi 

Pressure - LLEM#516 - static, nonuniform loading 

Pressure - LLEM#517 - static, nonuniform loading 

Pressure - LLEM#518 - static, nonuniform loading 

Pressure - LLEM#519 - static, nonuniform loading 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-85.—Category 3C - structure #7 - tests 7 to 10 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM tests #516–519. 

20 1 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

displacement - inches 

pressure - psi 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-86.—Category 3C - structure #8 - test 1 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #510. 

122 
18 0.9 

20 1 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-87.—Category 3C - structure #8 - test 2 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #511. 

pressure - psi 

displacement - inches 

20 1 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-88.—Category 3C - structure #8 - test 3 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #512. 

123 
18 0.9 

20 1 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-89.—Category 3C - structure #8 - test 4 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #513. 

pressure - psi 

displacement - inches 

20 1 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-90.—Category 3C - structure #8 - test 5 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #514. 

124 
18 0.9 

20 1 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Pressure - static, nonuniform loading 

Displacement 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

pressure - psi 

displacement - inches 

1.000 1.050 1.100 1.150 1.200 1.250 1.300 1.350 1.400 1.450 1.500 

time - seconds 

Figure A-91.—Category 3C - structure #8 - test 6 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #515. 

pressure - psi 

displacement - inches 

30 1 

Pressure - static, nonuniform loading 

Displacement 

0.9 

0.8 

0.7 

25 

20 

15 

10 

5 

0 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.100 1.120 1.140 1.160 1.180 1.200 1.220 1.240 1.260 1.280 1.300 

time - seconds 

Figure A-92.—Category 3C - structure #8 - test 7 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #516. 

125 
0.9 

30 1 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

pressure - psi 

displacement - inches 

1.100 1.120 1.140 1.160 1.180 1.200 1.220 1.240 1.260 1.280 1.300 

time - seconds 

Figure A-93.—Category 3C - structure #8 - test 8 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #517. 

pressure - psi 

displacement - inches 

30 1 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1.100 1.120 1.140 1.160 1.180 1.200 1.220 1.240 1.260 1.280 1.300 

time - seconds 

Figure A-94.—Category 3C - structure #8 - test 9 - static, nonuniform loading.
 

Solid-concrete-block ventilation stopping - LLEM test #518. 

126 
3.5 

30 4 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

3 

2.5 

2 

1.5 

1 

0.5 

0 

1.100 1.120 1.140 1.160 1.180 1.200 1.220 1.240 1.260 1.280 1.300 

time - seconds 

Figure A-95.—Category 3C - structure #8 - test 10 - static, nonuniform loading. 

Solid-concrete-block ventilation stopping - LLEM test #519. 

25 

pressure - psi 

pressure at 6.44 ft above the floor - (static, uniform loading) 

pressure at floor - (static, uniform loading) 

pressure at roof - (static, uniform loading) 

2500 2700 2900 3100 3300 3500 3700 3900 

time - seconds 

20 

15 

10 

5 

0 

Figure A-96.—Category 4 - structure #1 - test 1 - static, uniform loading.
 

Polymer and aggregate seal - test C8. 

127 
0 

1 

2 

3 

4 

5 

6 

7 

displacement - inches 

Displacement - LVDT 4 - 1 ft from roof 

Displacement - LVDT 5 - 2.5 ft from roof 

Displacement - LVDT 6 - Center of 8 ft by 20 ft seal 

Displacement - LVDT 7 - 2.5 ft from floor 

Displacement - LVDT 8 - 1 ft from floor 

2500 2700 2900 3100 3300 3500 3700 3900 

time - seconds 

Figure A-97.—Category 4 - structure #1 - test 1 - static, uniform loading.
 

Polymer and aggregate seal - test C8. 

0 

1 

2 

3 

4 

5 

6 

7 

displacement - inches 

Displacement - LVDT 1 - 1 ft from left rib 

Displacement - LVDT 2 - 4 ft from left rib 

Displacement - LVDT 6 - Center of 8 ft by 20 ft seal 

Displacement - LVDT 9 - 4 ft from right rib 

Displacement - LVDT 11 - 1 ft from right rib 

2500 2700 2900 3100 3300 3500 3700 3900 

time - seconds 

Figure A-98.—Category 4 - structure #1 - test 1 - static, uniform loading.
 

Polymer and aggregate seal - test C8. 

128 
0 

1 

2 

3 

4 

5 

6 

7 

displacement - inches 

Displacement - LVDT 6 - Center of 8 ft by 20 ft seal 

Displacement - LVDT 3 - 2 ft from floor, 4 ft from left rib 

Displacement - LVDT 10 - 2 ft from floor, 4 ft from right rib 

2500 2700 2900 3100 3300 3500 3700 3900 

time - seconds 

Figure A-99.—Category 4 - structure #1 - test 1 - static, uniform loading.
 

Polymer and aggregate seal - test C8. 

40 2 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 1.75 

1.5 

1.25 

1 

0.75 

0.5 

0.25 

0 

pressure - psi 

displacement - inches 

0.300 0.350 0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-100.—Category 5B - structure #1 - test 1 - static, nonuniform loading.
 

Wood-crib-block seal with Packsetter bags - LLEM test #396. 

129 

 

35 

40 2 

1.75 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

1.5 

1.25 

1 

0.75 

0.5 

0.25 

0 

0.300 0.350 0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 

time - seconds 

Figure A-101.—Category 5B - structure #1 - test 2 - static, nonuniform loading.
 

Wood-crib-block seal with Packsetter bags - LLEM test #399. 


 

40 

50 

pressure - psi 

displacement - inches 

60 0.12 

Pressure - static, nonuniform 

loading at centerline 

Pressure - static, nonuniform 

loading at downstream rib 

Pressure - static, nonuniform 

loading at upstream rib 

Displacement - (noise in data) 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

0.08 

30 0.06 

20 0.04 

10 0.02 

0 0 

Figure A-102.—Category 6A - structure #3 - test 1 - static, nonuniform loading.
 

Lightweight blocks - 24 in with hitching - LLEM test #508. 

0.1 

130 

 

70 3.5 

80 4 

Pressure - static, nonuniform loading at upstream rib 

Pressure - static, nonuniform loading at centerline 

Displacement 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-103.—Category 6A - structure #3 - test 2 - static, nonuniform loading.
 

Lightweight blocks - 24 in with hitching - LLEM test #509. 

60 

50 

40 

30 

20 

10 

0 

3 

2.5 

2 

1.5 

1 

0.5 

0 

pressure - psi 

displacement - inches 


 

20 

25 5 

pressure - psi 

displacement - inches 

4.5 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

15 

10 

5 

0 

Pressure - static, uniform loading 

Displacement 

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 

time - seconds 

Figure A-104.—Category 6A - structure #2 - test 1 - static, uniform loading.
 

Lightweight blocks - 24 in with hitching - test 4-48. 

131 

 

35 

0.45 

30 

0.4 

40 0.5 

Pressure - static, nonuniform loading at upstream 

Pressure - static, nonuniform loading at downstream 

Displacement 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 

time - seconds 

Figure A-105.—Category 6B - structure #1 - test 1 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #403. 

pressure - psi 

displacement - inches 

25 

20 

15 

10 

5 

0 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 


 

40 

35 

pressure - psi 

displacement - inches 

0.5 

Pressure - static, nonuniform loading 

Displacement 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 

time - seconds 

Figure A-106.—Category 6B - structure #1 - test 2 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #404. 

0.45 

30 

25 

20 

15 

10 

5 

0 

0.4 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

132 
35 0.45 

40 0.5 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

0.4 

0.35 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

pressure - psi 

displacement - inches 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 

time - seconds 

Figure A-107.—Category 6B - structure #1 - test 3 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #405. 

40 

pressure - psi 

displacement - inches 

1 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 0.875 

0.75 

0.625 

0.5 

0.375 

0.25 

0.125 

0 

0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 0.950 

time - seconds 

Figure A-108.—Category 6B - structure #1 - test 4 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #406. 

133 
0.09 

25 0.1 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading at centerline 

Displacement - (noise in data) 0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-109.—Category 6B - structure #2 - test 1 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #501. 

pressure - psi 

displacement - inches 

25 0.1 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading at 

centerline 

Displacement - (noise in data) 

0.09 

0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-110.—Category 6B - structure #2 - test 2 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #502. 

134 
25 

pressure - psi 

displacement - inches 

0.1 

Pressure - static, nonuniform loading at centerline 0.09 

Displacement - (noise in data) 

20 0.08 

0.07 

15 0.06 

0.05 

10 0.04 

0.03 

5 0.02 

0.01 

0 0 

0.400 0.600 0.800 1.000 1.200 1.400 1.600 1.800 2.000 2.200 2.400 

time - seconds 

Figure A-111.—Category 6B - structure #2 - test 3 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #503. 

pressure - psi 

displacement - inches 

25 0.1 

Pressure - static, nonuniform loading at centerline 

0.09 

Displacement - (noise in data) 

20 0.08 

0.07 

15 0.06 

0.05 

10 0.04 

0.03 

5 0.02 

0.01 

0 0 

0.400 0.600 0.800 1.000 1.200 1.400 1.600 1.800 2.000 2.200 2.400 

time - seconds 

Figure A-112.—Category 6B - structure #2 - test 4 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #504. 

135 
45 0.09 

50 0.1 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading at centerline 

Displacement - (noise in data) 

0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

pressure - psi 

displacement - inches 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-113.—Category 6B - structure #2 - test 5 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #505. 

90 

100 

pressure - psi 

displacement - inches 

0.1 

Pressure - static, nonuniform loading at centerline 

Displacement - (noise in data) 

0.09 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-114.—Category 6B - structure #2 - test 6 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #506. 

136 
 

80 0.08 

100 

Pressure - static, nonuniform loading at centerline 

Displacement - (noise in data) 

0.1 

90 0.09 

70 

60 

50 

40 

30 

20 

10 

0 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

0 

displacement - inches 

pressure - psi 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-115.—Category 6B - structure #2 - test 7 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #507. 

150 

pressure - psi 

-100.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Pressure - static, nonuniform loading at centerline 

Pressure - static, nonuniform loading at centerline 

130 

110 

90 

70 

50 

30 

10 

Figure A-116.—Category 6B - structure #2 - tests 8 and 9 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM tests #508–509. 

137 
 

35 0.18 

40 0.2 

pressure - psi 

displacement - inches 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement - (noise in data) 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-117.—Category 6B - structure #3 - test 1 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #501. 

pressure - psi 

displacement - inches 

60 6 

Pressure - static, nonuniform loading 

Displacement 

50 5 

40 

30 

20 

10 

0 

4 

3 

2 

1 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-118.—Category 6B - structure #3 - test 2 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #502. 

138 
pressure - psi 

displacement - inches 

20 0.08 

Pressure - static, nonuniform loading 18 0.07 Displacement - (noise in data) 

16 

0.06 

14 

12 0.05 

10 0.04 

8 0.03 

6 

0.02 

4 

2 0.01 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 3.000 

time - seconds 

Figure A-119.—Category 6B - structure #4 - test 1 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #503. 

pressure - psi 

displacement - inches 

25 0.2 

Pressure - static, nonuniform loading 

0.18 

Displacement - (noise in data) 

20 0.16 

0.14 

15 0.12 

0.1 

10 0.08 

0.06 

5 0.04 

0.02 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 3.000 

time - seconds 

Figure A-120.—Category 6B - structure #4 - test 2 - static, nonuniform loading. 

Lightweight blocks - 40 in, no hitching - LLEM test #504. 

139 
45 4.5 

50 5 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Pressure - static, nonuniform loading 

Displacement 

pressure - psi 

displacement - inches 

4 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-121.—Category 6B - structure #4 - test 3 - static, nonuniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #505. 

pressure - psi 

displacement - inches 

80 8 

70 

60 

50 

40 

30 

20 

10 

0 

Pressure - reflected, uniform loading at rib 

Pressure - reflected, uniform loading at centerline 

Displacement 

7 

6 

5 

4 

3 

2 

1 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-122.—Category 6B - structure #5 - test 1 - reflected, uniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #502. 

140 
pressure - psi 

displacement - inches 

20 0.1 

Pressure - reflected, uniform loading at rib 18 0.09 

Displacement - (noise in data) 

16 0.08 

14 0.07 

12 0.06 

10 0.05 

8 0.04 

6 0.03 

4 0.02 

2 0.01 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 3.000 

time - seconds 

Figure A-123.—Category 6B - structure #6 - test 1 - reflected, uniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #503. 

pressure - psi 

displacement - inches 

25 0.2 

Pressure - reflected, uniform loading at rib 0.18 

Displacement - (noise in data) 

20 0.16 

0.14 

15 0.12 

0.1 

10 0.08 

0.06 

5 0.04 

0.02 

0 0 

0.000 0.500 1.000 1.500 2.000 2.500 3.000 

time - seconds 

Figure A-124.—Category 6B - structure #6 - test 2 - reflected, uniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #504. 

141 
80 8 

70 7 

60 

50 

40 

30 

20 

10 

0 

Pressure - reflected, uniform loading at rib 

Displacement 

pressure - psi 

displacement - inches 

6 

5 

4 

3 

2 

1 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-125.—Category 6B - structure #6 - test 3 - reflected, uniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #505. 

pressure - psi 

displacement - inches 

120 8

100 

80 

60 

40 

20 

0 

Pressure - reflected, uniform loading at rib 

Displacement 7 

6 

5 

4 

3 

2 

1 

0 

0.400 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 0.850 0.900 

time - seconds 

Figure A-126.—Category 6B - structure #7 - test 1 - reflected, uniform loading.
 

Lightweight blocks - 40 in, no hitching - LLEM test #506. 

142 
0 

5 

10 

15 

20 

25 

pressure - psi 

0 

0.5 

1 

1.5 

2 

2.5 

3 

3.5 

4 

4.5 

5 

displacement - inches 

Pressure - static, uniform loading 

Displacement 

0 0.5 1 1.5 2 2.5 3

time - seconds 

Figure A-127.—Category 6B - structure #8 - test 1 - static, uniform loading.

 Lightweight blocks - 40 in, no hitching - test C5-53E. 

143 
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DHHS (NIOSH) Publication No. 2009-151 

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