NATIONAL BUREAU OF STANDARDS REPORT

10.0 3079

Requirements for

Concrete-Masonry Construction

(Revision of NBS Report 2462)

By

Cyrus C. Fishburn

<5

^

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measmements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infirared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Ramological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Smrface Cheipistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chenustry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fihrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance EHectronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

MissUe Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense. • Office of Basic Instrumentation • Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS

1000-30-4801 January 30, 1954

Requirements for

Concrete-Masonry Construction

(Revision of NBS Report 2462)

By

Cyrus C. Fishburn

To

Office of Chief of Engineers

Department of the Army

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Th» publica

unleaiperm 25.D.C. S

tally prepa

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 201 5.

'hole or In part, It prohibited

au of Standard!, Washington

ilch a report haa been speclfiIcular report for Iti own use.

REPORT

3079
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Table of Contents

1, SCOPE 1

2„ CODES, STANDARDS AND SPECIFICATIONS o « o o

3. CONCRETE MASONRY UNITS o » o . . .

3a, Units for fire walls ^ . c « 3bo Concrete building brick . ® c o ® 3c o Shrinkage o o ^ e o , 3d c Moisture content o ® « e . « 3® o Storage Gcaoococaoe«©

3fc Manufacture . » o ^ ® <> » « e * <> 3go Special shapes , o o o o » o ® » 3h« Dimensions of units . , ^ *

4. MORTAR, GROUT AND THEIR USE ^ » 4a c Definition . » » c ® => » , 4b® Mortar specifications ® o » ® ® o 4cs Water retention » , = ® ® « e <, « 4d o Choice of mortar , c * c c o ^ ® 4e G Thickness of mortar joints « o « 4fe Joints in hollow-unit masonry * ® 4go Joints in solid-unit masonry . , 4ho Type of exposed joints .. . ® « o 4ie Time limit in use of- fresh mortar

4 jo Retemperlng of mortar ® o » ® « o

l_|_k o Grout Goe.rooo?o®o«e©

5® CONTROL OP SHRINKAGE CRACKING o o . «

4ao Expansion joints . ^ « o ® ® 5b® Bond beams , o . « e ^ „ o ® o <, o o 5c o Function of bond beams o o <, o . . » o « 5d® Location of bond beams

5e G Control joints , « ® o o <, c * « ® ^ . 5fo Function and location of control joints « 5go Spacing of control joints in straight wall

S 6 O IL O S AOOOAOOOACeVdOO'

5h« Joint reinforcement e o » » ® « « o <, s c 5i» Function of joint reinforcement ® « c 5jo Use and location of joint reinforcement « 5k® Splices in joint reinforcement « . , « ^

© c

© o

2

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Table of Contents

6. STRUCTURAL DESIGN . . .

Page

No».

18

6a

.

- 6b - 6 c r- 6d.

6e «, 6f

.

6go

6ho

6i

«

6

6k,

6lc

6m o 6rio

6o

.

6p

6q.

6po

6s r 6t

.

6uCompressive stresses r c , , . r c , c • Design against seismic forces . ^ r , , . Lateral support o n « r . Ratio of height or length of wall to wall

thickness ^ - o c . , , ^ ^ . Height of piers v- ^ 'c ^ . r , , Thickness of single wythe bearing walls , , Thickness of stiffened bearing walls of

solid units ^ . o , o c , c- c r , c ? Thickness of cavity walls o o ^ c . , ^ Thickness of nonbearing exterior walls

Thickness of nonbearing partitions » , . Decrease In thickness^ o . Thickness of foundation walls „ , , , , Depth of foundation walls

Multiple wythe s In other than cavity walls

Bonding of cavity walls r . , , c * . . Bonding of Intersecting walls , . c , . Bonding of enclosure walls to columns , . Reinforced masonry . o r r. ^ , r , . ^ Mall openings , o ^ - c . r , . Modular design ^ . c ^ Drainage of walls c c , c

« 18

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7c ERECTION 24

7a- Bracing to resist lateral loads

7b > Wetting of masonry units - c , 7c, Joint reinforcement , , , ^ 7d, Protection against freezing r, c Jen Cleaning ^ - - , - - , c = . c

24

2^

25

25

25

8. PAINTING c c . c c , 25

8a c Base coats on rough-textured walls » . 25

8br Base coats on smooth-textured walls 26

8c, Application of base coats 26

8d. Pneumatically applied cementitious base coats 26

8e, Finish coats . c ^ . . , . . . , , . , 27

8f, Calking . o o - - , , c . c .. . . -v - 27
Table of Contents

Page

No.

SAMPLING AND TESTING CONCRETE MASONRY UNITS . . 2?

9a. Drying shrinkage, selection of specimens. . 2?

9b. Test for drying shrinkage 27

9c. Periodical check on moisture content. ... 28

9d. Staining test for aggregate in units. . . . 28

9e . Test for surface popouts. 28
Illustrati ons

Figur

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Typical bond beam units

Bond beam lintels . exteri or wall.

Shrinkage control joint using 3-<^ell control

joint block.

Shrinkage control joint using 2TM cell control

joint block..

Shrinkage control joint using open end stretcher

block and concrete core„

Wall intersect! ons

c

Typical wall and partition intersection.

Enclosure wall construction.

Plan and detail of joint reinforcement showing

lapped splices.

Concrete frame, column and wall intersection.

Panel wall in concrete frame construction.

Typical steel column wall intersection.

Roof and wall intersections.

Intersection of load-bearing wall and concrete roof

slab for buildings less than. 40 ft in length.,

Typical wall section at wood joist floor.

Masonry cavity wall.

Typical window framing, exterior.

Typical door fra.ming, exterior,.

Detail of typical metal door frame in partition.

Optional types of typical jamb anchors for metal

door frames in interior partitions,

20
lo SCOPE

This report suggests criteria to be followed for the

use of concrete masonry in military construction. It discusses the selection of materials, the preparation of drawings

and specifications for the structure, the control of shrinkage cracking in the walls, the erection of the walls and their

painting. The report is not concerned with floors, roofs or

other constructions not involving the use of concrete masonry

units except Insofar as such constructions affect the use of

concrete masonry, particularly of concrete masonry walls,

2 = CODES, STANDARDS AND SPECIFICATIONS

The American Standard Building Code Requirements for

Masonry (ASA Al].! , 1-1953) s hereinafter referred to as A[j.lol,

is the basis for masonry design and construction. Sections

of this code that are applicable to concrete masonry are

automatically included in this report without further reference and should be followed, unless modified herein. It

should be clearly noted that any requirement in this report

that conflicts with any codes, standards or specification

takes precedence over the applicable section or sections of

such codes and standards,

3° CONCRETE MASONRY UNITS

A concrete masonry unit is a building 'unit made from

Portland cement and aggregate with or without the addition

of other suitable materials. The units should conform with

the requirements of the current ASTM Standards, These

standards are

Hollow Load-Bearing Concrete Masonry Units,

ASTM C90-52,

Hollow Nonload-Bearing Concrete Masonry Units,

ASTM C129-52,

Solid Load-Bearing Concrete Masonry Units,

ASTM Cli|5"52

Aggregate used in concrete masonry units should comply with

the requirements of one of the following ASTM Standards

j

Concrete Aggregate - ASTM Standard C33-53T

Concrete Aggregate, Lightweight - ASTM

Standard C130-1-1-2

^ 1 „
A new proposed. ASTM specification for ’'Lightweight Aggregate

for Concrete Masonry Units” may soon he approved as a tentative Standard, possibly under an ASTM number other than CI 3O 0 When this specification becomes available, any requirements

for staining and surface pop outs contained in it should be

noted and unless the aggregates are known to be sound, tests

for staining and surface popouts should be made „ These

tests are listed in section 9 of this reports However, the

test for surface popouts should be made on the units or

pieces of the face shells of the units, not the aggregates.

When there is evidence that cinder or other aggregate block

produced in an area may tend to stain or pop, the use of such

block as a facing may be restricted,

3a, Units for fire walls

Hollow concrete masonry units intended for use in fire

resistant walls should meet the requirements of Underwriters*

Laboratories Standard for Concrete Masonry Units, Subject

618 , If Underwriters’ certificate is required, it should be

so stated in the specifications.

3b „ Concrete building brick

The use of concrete building brick should be incidental

only and the use of larger concrete masonry units is preferred, Concrete building brick, if used, should comply with

the requirements of ASTM Standard C55“52,

3c

,

The potential shrinkage of concrete masonry units is

affected by the kinds of materials used and by manufacturing

and curing conditions at the plant. The potential shrinkage

is an Important factor affecting both the extent and the

control of shrinkage cracking in concrete masonry structures,

Concrete masonry units should, therefore, be classified into

two groups, group 1 or group 2, as listed below;

2 -
Drying Shrinkage Classification of Concrete Masonry UnitsKind of

Weight of unsonry

unit per cu ft Linear shrink age—/

masonry unit of concrete Group 1 Gr oup 2

lb percent percent

Concrete brick 100 or , more no limit 0,03 or less

Hollow or solid

concrete block

105 or more no limit 0,04 or less

Hollow or solid

concrete block

less than 105 no limit 0 0 05 or less

a/ The control of shrinkage cracking,

units is discussed in Section 5.

b/ See par, 9b for method of testing.

using group 1 and group

3d, Moisture c ontent

The average moisture content of all concrete masonry

units at the time of delivery should not exceed 30 percent of

the total absorption of the units. On approval by the Division

Engineer^ the limit of 30 percent on moisture content may be

increased in regions of high huriiidity (Mean Relative Humidity

of 80 percent or more) to 35 percent and may be reduced to 25

percent in regions of low humidity„

3e , Storage

Before erection and while in storage at the site of the

job, units must be protected from moisture and kept dry prior

to laying. Ho units should be placed directly upon the

ground while being stored. The contractor should be held

responsible for protecting the units. Units which fail to

meet the raoi s ture- c ontent limitation at any time during the

storage on the job, should be dried and should not be laid

until tests prove them to be satisfactory,

3f » Manuf acture

Units should be of the same manufacture and composition

for each building, unless otherwise approved by the Contracting Officer, When it is permitted that the units be made by

more than one manufacturer for use in the same building, they

should be of similar composition, size, and appearance. All

units should be sound and free from cracks or other defects

which would Interfere with their proper setting or impair the

- 3

-
strength, appearance, or durability of the construction,

3g , Special shapes

Concrete masonry units of special shapes such as beam

lintel blocks and bond beam blocks, see figure 1, should conform with the general requirements for concrete masonry

stretcher units, excepting shape and overall dimension,

3h, Dimensions of units

Concrete masonry units should be of modular dimensions

where available and should be used in modular designs. (See

section 1,6.11.2 of Alj.1,1).

MORTAR, G-ROUT AND THEIR USE

To obtain masonry joints of high quality with ordinary

construction methods, an intimate and complete contact of

the mortar with the surface of the m.asonry unit is necessary.

Although the skill and the amount of effort exerted by the

mason affect the quality of the joints in masonry, the

quality and the condition of the materials are the important

factors. Mortars which have low water retentivities tend to

stiffen so rapidly when in contact with the surface of a dry,

absorptive masonry unit that they become too dry and stiff

to permit an Intimate and complete contact of the mortar

when the second unit is pressed against it. Also, mortars

of low water retentivity tend to "bleed” if allowed to stand.

The wetness ( f1 owability) of the mortar being used by the

mason has an important influence on the extent and intimacy

of the bond between the mortar and the units; the wetter the

mortar the more complete and the stronger the bond between

mortar and unit and the more watertight the joint.

Iqa. Defini ti on

Mortar is a plastic mixture of cementitious materials,

fine aggregates and water used to bond masonry or other

structural units. Mortar of pouring consistency is termed

grout

,

4-b . Mortar specifications

Mortar, mortar materials and proportioning should comply with the requirements of ASTM Standard C270-52T. This

Standard contains two alternate specifications designated

as the Property Specifications and the Proportion Specifications. Either of these two alternate specifications for

mortar of types A-1, A-2 and B may be used, provided that

- ]q -
mortar specified under the Proportion Specification meets

the requirement for water retention given in Section l\.c o Mortar of types C and D should not be specifiedo The compressive strength requirements (Property Specification) for

these mortars are:

Average Compressive

Mortar Type Strength of 2-ino

. Cubes at 28 Days

p si

A -1 - 2500

A-2 1800

B 750

4.C . Water retention

Mortar made of the same materials and proportions to

be used on the construction, mixed to an initial flow of

125 to llj-O per cent, should have a flow after suction (water

retention) of 75 percent or more of that immediately after

mixing. The apparatus to be used and the method of determining water retention should be in accordance with Section

30 of ASTM Standard C 91 - 51 j except that the mortar should be

of the materials, proportions and initial flow described

above at the head of this section ( 4 c) o Mortars specified

under the Proportion Specification of C 270 - 52T should be

tested and required to meet the minimum water retention of

75 percent. The water retention of each type of mortar

used should be measured at least once each week during construction of the masonry.

4 d» Choice of mortar

Masonry should be laid in mortar of the types specified

in the following table:

Kind of masonr

Found at 1 on

Walls of solid units

Walls of hollow units

Hollow walls and cavity walls

Masonry other than foundation masonry

Piers of solid masonry

Piers of hollow units

Walls of solid masonry

Walls of hollow units; load bearing or

exterior walls and hollow walls 12 in, or more in thickness

Type of mortar

Ai, A2 or B

Aq or A2

Aq or A2

Aq, A 2 or B

Aq or A2

Aq , A2 or B

- 5 -

Aq, A2 or B
Masonry other than foundation masonry (Cont’d.)

Hollow walls less than 12 in, in thick- . j ness where assumed design wind pressure:—'

(a) exceeds 20 Ib/ft^ Ap or A 2

(b) does not exceed 20 Ib/ft^ Ap, or B

Linings of existing masonry Ap or A 2

Masonry other than above Ap , A2 or B

!_/ For design wind pressures, consult Am, Std, Building Code

Requirements for Minimum Design Loads in Buildings and

other Structures, ASA A58,1 (current edition),

ip e , Thickness of mortar joints

Wherever possible, the thickness of both horizontal (bed)

and of vertical (head and collar) joints should be 3/8 in.

(modular dimension),

lpf , Joints in hollow-unit masonry

Full mortar bedding of both the face shells and webs of

hollow concrete masonry units should be required as follows:

(a) Under the first or starting course laid on footings

and solid foundation walls

(b) In piers, columns and pilasters Intended to carry

heavy loads

All other hollow units need be bedded under the face shells only.

The first course of single-wythe panel walls containing weep

holes and supported on spandrel beams should be bedded under the

face shells only to permit drainage of water to the weep holes,

see figure 11, The use of weep holes in such walls is in accordance with OCE policy. Mortar for vertical (head) joints should

be applied over the full width of the face shells,

lpg, Joints in solid-unit masonry

For masonry of solid units, the bed and head joints should

be filled as solidly as is practicable. Mortar in the bed joints

should be spread over the full area of the block and may be furrowed, Similarly, mortar for the head joints should be heavily

buttered and applied over the full area of the ends of the block,

l|h. Type of exposed joints

If the weather side of a wall is to be coated with a portland

cement paint or a pneumatically applied cementitious coating, the

joints in the exposed (weather) face should be cut flush with the

faces of the units. The rough texture of the cut joint provides

a better bonding surface for a cementitious coating than does the

smooth compacted mortar surface of the tooled joint. The durability and the weather resistance of the coating covering the

joints may, therefore, be improved by cutting, not tooling the

j oints

,

6
[j-i » Time limit in use of fresh mortar

Mortars which have greatly stiffened because of chemical

reaction (hydration) should not be used but the stiffening

resulting from the evaporation of moisture from the mortar

should not be confused with the effects of chemical reaction,.

Determination of the cause of stiffening is difficult and an

arbitrary rule on a time limit for the use of mortar may be

substituted for this determinati on » At air temperatures of

80°F or higher, mortars should be used and placed in the wall

within two and one-half hours after mixing* At temperatures

of less than 80°P the mortar should be used within three an.d

one-half hours after mixing* Mortar which is not used during the time intervals given above should be discarded and

thrown avjay* If the cement or cements used in the mortar

have been tested and the observed time of initial set, as

determined under ASTM Standard C266-51T (Gilmore Method)

is known, an alternative method of debermining the time

interval^ during which the mortar should be placed in the

wall, may be used. These alternative time intervals are:

Air temperature Tlm.e interval after mixing

80° F or higher Time of initial set less 1 hr.

Less than 80° F Time of initial set less l/2 hr.

If the mortar contains two cements (a portland and a masonry

cement), the least observed time of initial set should be

used* Under laboratory conditions, most portland and masonry

cements will attain an initial set in three to five hours*

However, at high temperatures and under other possible job

conditions the hydration of the cement may proceed faster

than in the laboratory*

4 j , Retempering of mortar

Mortars which have stiffened should be retempered to

restore their workability and water should be added as frequently as needed during the maximum time intervals given

in section 4i above* Masons should be encouraged to use as much mixing water as is practicable without impairing the

workability of the mortar* Although the strength of the

mortar may be slightly reduced by the liberal use of water

in mixing and retempering; the lack of retempering may

seriously reduce the flexural and the tensile strength of

the masonry because of poor bonding of the units to dry,

stiff mortar*

- 7 -
Ij-ko Grout

Grout should be Type A-1 or Type A-2 mortar to which is

added water to produce consistency for pouring without segregation of constituents of the mortar. Type A~1 grout

should be used with Type A-1 mortar; either Type A-1 or Type

A-2 grout should be used with Type A-2 mortar,

control of shrinkage CRACKIITG

The shrinkage cracking of concrete masonry may be controlled by drying the units j by selecting units having a

limited potential shrinkage (Group 2 units) ^ and by the use

of joint r e inf or cement bond beams, and control joints. The

drying and the selection of units are discussed in Section 3

of this report. The following requirements for bond beams,

control joints and joint reinforcements are based chiefly on

the use of Group 1 units for which there are po limits on

maximum linear shrinkage. Summaries of the requirements for

control joints, bond beams and joint reinforcement for masonry of both Group 1 and Group 2 units are tabulated at the

end of this Section, The measures used to control shrinkage

cracking in concrete masonry walls should not be confused

with the use of expan.si on- j oint s and c ontr acti on- j oint s in

buildings, A short discussion of exp ansi on- j oint s in buildings is contained in the next paragraph of this section,

5a . Exp ansi on joints

Expansion joints should completely separate the building structure from bottom to top along a vertical plane and

should be capable of functioning either as an expansion

joint or as a contraction joint, as the structure expands

or contracts. There is no uniform practice for designing

the joints. In a framed structure, the division of the

building may be accomplished by using double columns and

double girders or cantilever floor and roof slabs which

meet at the joint. The joint may be po:’ otected from leakage

and the weather by sliding plates or a metal sheet. When

required, expansion joints may be placed at changes in

elevation of the foundations or superstructures and at junctions in L-,T- or U-shaped buildings. Reinforced concrete

buildings of 300 ft, or more in length have been built without expansion joints and, when properly reinforced, have not

cracked badly. However, complete separation of the structure should be made with expansion joints at intervals not

exceeding 200 ft, in long straight buildings , The discussion

of shrinkage control joints in concrete masonry walls, given

later in this section, does not pertain to expansion joints.

While a shrinkage control joint may be modified and used as

8
part of an expansion joint through a structure ^ it should

then be defined as an expansi on=c ontracti on joint and not as

a control j oint o

^b o Bond beams

Bond beams may consist of bond beam or lintel beam units

filled with reinforced concretej see figure 2 for bond beam

and lintel beam sections o Recessed lintel units and jamb

units are also made and are available in some sections of the

country,, Concrete should conform with the requirements of

OCE Guide Specification CE20I4.J Class B 2500/ln, ^ Reinforce

ment should consist of at least two No„ I4. deformed bars or the equivalent in cross sectional area» The reinforcement

should conform with the requirements of ASTM Standard A305“

50T« When the concrete fill in the beam is deeper than 7 IHo

at least half as much reinforcement should be added near the

top of the beam as is required in the bottomo Cast=ln place

reinforced concrete beams may be used instead of filled mason

ry-unlt bond beams „ Cast-in place or precast concrete beams

may be used as lintels

o

5 c 0 Fun.ction of bond beams

The fun.ctions of bond beams are as follows s

(a) To reduce the effects on the masonry of differential volume changes between the foundation

and superstructure walls

o

(b) As a continuous Interlocking structural tie

connecting the exterior load bearing walls of

buildings whose dimensions are small enough not

to require expansion or expansi on- contract! on

joints „ They may be similarly used between the

expansion joints in larger buildings a

(c) As a structural member transmitting lateral loads

on the wall to other connecting structural elements o

(d) To minimize shrinkage cracking at wall openings,,

particularly when used as a more or less continuous lintel „ The bond beam may also control the

shrinkage cracking in the masonry immediately

above and below it but its effectiveness diminishes rapidly with vertical distance from the

beamo The efficiency of steel to control shrinkage cracking is greater when used as joint reinforcement than when used in a bond beamo

9 =
It is evident that the bond beam functions not only as a

structural element but also as a control against shrinkage

cracking o The use of the bond beam as a structural element

alone, is further discussed in section 6* In general, bond

beams may be cut at control joints provided their structural

functions as lintels and as members transmitting lateral

loads to other structural elements are not thereby Impalredo

If a bond beam is cut at a control joint, provision should

be made to transmit lateral forces and to give protection

from the weather at the cut section. If joint reinforcement is used in lieu of control joints to control shrinkage, the bond beam need be cut only if its length is

excessive, as where expansion joints are used.

5d. Location of bond beams

Bond beams should be placed in the top courses of concrete masonry foundation walls more than 30 in. in height.

If the bond beam is not used, the footing should be reinforced. Bond beams should also be placed at or near the

top course of all load-bearing walls built of concrete masonry units. Where high wind loads may be expected and where

large volume changes may occur in the masonry, additional

bond beams may be placed between the top and bottom of concrete masonry walls. For walls of Group 1 units, bond beams

should be placed at vertical intervals of not more than 12

ft, but not between openings. Bond beams should also be

placed in non-bearing walls used as lateral support for

load-bearing walls and at the same elevations as in the loadbearing wall but not between openings, see section 6c. When

the bond beam is not broken, at a control joint, a dummy

joint simulating a control joint may be placed in the exposed face of the bond beam to give the appearance of a

continuation of the joint through the beam. Bond beams

should be terminated at expansion joints. The minimum requirements for the use and location of bond beams are

tabulated at the end of Section 5 and are summarized below*

1. At the top of concrete masonry foundation walls

more than 30 in. high (provided the footing is

reinforced) .

2. At or near the top of load-bearing concrete

masonry walls. The bond beam should be placed

in the top course if the top of the wall is

tied to the roof or if the wall is subjected

to lateral thrust from the roof.

10 -
3o In walls of Group 1 units at intervals not exceeding 12 fto in wall height but not between openings.

5^ Shrinkage control joints are vertical joints which provide a continuous vertical separation between bond beams

through the entire thickness of a concrete masonry wall ^ including any facing or rigid finishes. The joints may be

masked and the possibility of leakage of rain through them

may be reduced by the use of pilaster blocks and by recesses

in. monolithic concrete column faces. Provision should be

made for the transfer of lateral loads across the joint. This

may be done by using control joint blocks or by filling the

space between open-end units with mortar or concrete^ see

figures 3s 4? and The joints on the weather side of the

wall should be faced and sealed with plastic calking compound, Formed synthetic rubber or vinyl plastic stripping

may be a suitable substitute for calking compound. The vertical joint behind the calking should contain mortar and the

mortar should be applied to both faces of the wall. The mortar on the inside face of the joint may be raked^ for appearance o

5f o Function and location of control joints

The function of a control joint is to assist in relieving the horizontal stresses in straight wall sections,,

resulting from moisture and temperature movement. Shrinkage

control joints are primarily intended to f'unction as contraction joints. If considerable volume changes occur in concrete

masonry walls ^ the control joint may also be required to

function as would an expansi on-c ontracti on joint. In such

cases it may be undesirable to place mortar in the vertical

joint but to fill with calking only. Control joints should

be placed at intersections x^rhere the intersecting walls are

longer than 12 feet. The joint may be placed in the cross

wall at a distance equal to l/2 the height of the cross wall

f.rom the intersection. If the intersecting walls are not

needed as lateral supports for each other or if they are

interconnected with bond beams j the control joint may be

placed at the wall intersect! on^ preferably on the inside

face of exterior walls. It is not implied that control

joints should be used at the corners of the exterior walls

in buildings of square or of rectangular shape , especially

if the walls contain joint reinforcement. Control joints

should not pass through bond beams, sills or lintels if

cutting of the bond beam or lintel impairs the structural

11 =
stability of the wall op of the building as a whole „ When

placed at or below wall openings, the control joint may re-= quire the use of slip joints under the ends of lintels and

will prevent the effective use of joint reinforcement to con»

trol the width of shrinkage cracks at these highly stressed

locations,, The use of slip joints is not desirable „ Control

joints and methods of bonding Intersecting walls are shown in

figures 6 and 7«

5go Spacing

The proper spacing between control joints in straight

walls depends upon the restraints to lAjhich the wall is subjected, the exposure conditions, the amount and distribution

of reinforcement, if used, and the kind of block or amount of

shrinkage o This spacing should be equal to or slightly less

than the more or less uniform distance between vertical

shrinkage cracks that would normally occur if the wall were

built without control joint So For walls of Group 1 units,

without joint reinforcement, this spacing should not exceed

l5 ft, see option 2 of the table at the end of this sectiono

For walls of Group 2 units, the spacing should not exceed 30

ft. If the control joints are not properly placed and if the

walls are without joint reinforcement, vertical shrinkage

cracks may occur. These cracks may function instead of the

control joints and may be unsightly, especially where they

pass through the units. For straight walls, it is possible

that joint reinforcement which strengthens the masonry and

which requires no maintenance is more reliable in controlling

shrinkage than is the control joint. Since control joint

blocks are not available in i|.-=in, block widths and since the

4.“in, thick blocks are flat ended making it difficult to provide lateral stability at a control joint, the joint reinforcement may be preferred to control joints in cavity walls using

Lj-“in, blocks. The minimum requirements for the use and location of control joints are tabulated at the end of Section 5

and are summarized below?

1, At the wall intersections in L-, T- , and U-shaped

buildings where expansion joints are not used,

2, At or near cross wall intersections if the intersecting walls are both 12 ft, or more in length.

3o If joint reinforcement is not used, control joints

should be placed at intervals not exceeding l5 ft,

in walls of Group 1 units and 30 ft, in walls of

Group 2 units.

12 -
5h. « J pint reinforcement

Joint reinforcement consists of flat (not rolled) strips

of welded wire fabric in the bed joints of the masonry. The

distance between the centers of the two longitudinal wires

in a strip depends upon the width of the block and for blocks

having face shells 1 l/Lj. in-, thick should be 2 in, less than

the nominal block width. The longitudinal wires may be either

smooth or preferably deformed and zinc-coated and should not

be smaller than size No* 8, American Steel and Wire gauge.

Since the stress in smooth longitudinal reinforcement is developed principally by bearing of the cross wires in the

mortar bed, the cross wires should intersect above or below

the longitudinal wire and should be spaced not more than 6 in,

apart center to center. To reduce the possibility of exposing

the reinforcement in the wall faces the cross wires should extend only to the outer sides of the longitudinal wires and

should preferably be zinc- c oated , If the longitudinal wires

are deformed, the cross wires should be spaced not more than

l6 in. on centers and may be placed between the longitudinal

wires and in the same plane. The cross wires should not be

smaller in size than No, 12 A,.S,& W, gauge. Joint reinforcement should be furnished in straight flat pieces of convenient lengths ranging from 10 to 20 or more feet in length.

Special shapes of joint reinforcement may be provided for wall

intersections and corners, thereby reducing the amount of

cutting and bending needed on the job. Joint reinforcement

should terminate at control joints. The wire used in joint

reinforcement should meet the requirements of ASTM Standard

ASTM Standard A82-34-.

5i * Function of joint reinforcement

Under the usual field service conditions and regardless

of the kinds of units used, it is probable that the extensibility of plain, unreinforced walls built without control

joints will be exceeded and some shrinkage cracking will

occur if the free linear shrinkage of the units is equal to

or greater than 0,02 percent. After the first cracks occur,

their Width, but not necessarily their number, would tend to

increase with further increase in shrinkage. Joint reinforcement will not prevent the appearance of fine shrinkage cracks

in the masonry. It will tend to increase the number of the

cracks and to decrease their width, and since most of the

cracks in reinforced walls will occur at head joints, it will

greatly reduce the number of cracked blocks. If the percentage of reinforced bed joints is 50 or greater and if the

shrinkage of the units is not too great, it is possible that

the widths of shrinkage cracks may be held to a maximum of

- 13 -
about 0,01 in with a minimum use of control joints. It

should be noted that the width of cracks will also be dependent upon the percentage of reinforced joints as well as on

the amount of steel placed in a joint. Joint reinforcement

should preferably be used at wall openings and at other points

where high tensile stresses resulting from shrinkage are probable, In general, joint reinforcement strengthens the masonry,

requires no maintenance, and may be preferred to control

joints to control shrinkage cracking in concrete masonry walls,

especially in cavity type walls. Since a given amount of

steel may be more widely distributed as joint reinforcement

than when concentrated in a bond beam, the joint reinforcement should be preferred to bond beams to control shrinkage

cracking

,

5 j 9 Use and location

At openings in walls of Group 1 units, joint reinforcement should be placed in the first bed joint over simply

supported lintels and in the first two bed joints under a sill. At openings in walls of Group 2 units, joint reinforcement should be placed only in the first bed joint under

a sill. The joint reinforcement at openings should extend

at least 20 in, beyond the ends of sills and lintels or through the full distance to the end of the wall whichever

is the smaller. Joint reinforcement at openings in a concrete frame building and at other openings is shown in

figures 8, 17 and l8. Except that the previously stated

minimum requirements for control joints be followed, joint

reinforcement, in addition to that required at openings, may

be used in lieu of or in conjunction with control joints.

When used in lieu of control joints, the joint reinforcement should be placed in every bed joint in walls of Group 1

units and in alternate bed joints in walls of Group 2 units.

Except for that required at openings, no joint reinforcement

is required in walls 12 ft, or less, in length. Wo joint

reinforcement is required in the bed joint supporting a bond

beam. The minimum requirements for the use and location of

joint reinforcement are listed at the end of Sec.tion

5k , Splices in joint reinforcement

Joint reinforcement should be lapped at splices and the

splice should develop the tensile strength of the. i ongitudinal steel. For smooth longitudinal steel, the lapped splices

should contain at least one cross wire located near the end

of each strip. The lapped splices in deformed joint reinforcement may also, and preferably should, contain cross

wires. If the cross wires are placed in the same plane as

2/ Approximate value only, not based on field experience.

- 14 -
that of the deformed longitudinal wires, heavier joint reinforcement may be used for a given joint thickness than is

the case when the cross wires extend over the longitudinal

wires. For a 3/8“ in, thick bed joint. No. 8 is the maximum

size smooth wire that may be used without thickening the

joint! if deformed wire is used with cross wires in the

same plane, the longitudinal wires may be No. 6 size, see

sections A-A and B-B of figure 9«

- 15 “
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6, STRUCTURAL DESIGN

As previously stated, in section 2 , the American Standard

Building Code Requirements for Masonry Al;!,! are the basis for

structural deslgUo Insofar as these requirements are applicable

to concrete masonry, they should be followed without further

reference unless modified herein. The necessity for modification results chiefly from the use of control joints and bond

beams (section 5) and their effects on the structural stability

of the walls and of the structure as a whole. The modifications

pertain chiefly to single wythe walls of either hollow or solid

units and to cavity walls of hollow units.

6a „ Compressive stresses

The compressive stresses on the gross cross-sectional area

of concrete masonry should not exceed the values listed below:

Kinds of masonry and of

concrete masonry units • Ai

Type of Mortar

: A2 : B

lb/in .

2

lb/in .2 Ib/in „

2

Masonry of hollow load-bearing

concrete masonry units

. 85 75 70

Solid masonry of concrete brick

and of solid load-bearing concrete masonry units:

Grade A 175 160 150

Grade B. 125 115 100

Grouted solid masonry of concrete

brick and of solid load-bearing concrete masonry units:

Grade A 275 215 155

Grade B 225 175 125

Piers of hollow -units, cellular

spaces filled as in Bection 6e

Hollow walls, cavity i/ or masonry

b onded

Solid units, Grade A

105 95, 90

li|0 130 110

Solid units, Grade B 100 90 80

Hollow units 70 60 55

\J On gross cross-sectional area of wall minus area of cavity

between wythes (leaves). The allowable compressive stresses

for cavity walls are based upon the assumption that the

floor loads bear upon but one of the two wythes. When

hollow walls are loaded concentrically, the allowable

stresses may be increased by 25 percent.

6b o Design against seismic forces

The stresses used in the design of concrete masonry structure against seismic forces should conform with the requirements

of the Uniform Building Code of the Pacific Coast Building Officials Conference, insofar as they are applicable.

- 18 -
6 c o Lateral support

Lateral support may be obtained by cross walls j piers

3

pilasters s columns j, or buttresses 3 when the limiting distance

is measured horizontally ^ or by floors and roofs when the

limiting distance is measured vertically,. Sufficient bond

or anchorage should be provided between walls and their

supports to resist the assumed horizontal forces acting either

inward or outwardo The structural members relied upon for

lateral support should have sufficient strength and stability

to transfer the horizontal forces 3 acting in either direction

to adjacent structural members or to the ground o Care should

be taken that the structural members such as cross walls

roofs and columns that are relied upon for lateral support

do not as a result of changes in temperature and in moisture

content 3 exert excessive or unusual thrust against or pull

upon the walls they are Intended to supporto Cross ^^ralls

more than 12 ft in lengthy used as lateral supports for the

walls 3 should contain control joints o If the control joint

is placed at the intersections bond beams should be used as outlined in Section 5 ° The control joints should preferably

be placed about one-half of the wall height from the wall

intersection but not more than 12 ft from, the intersect! on o The bond beams in the intersecting walls should be inter=

locking,, as continuous as possible and at the sam.e elevations

in each wall o Details showing methods of bonding concrete

masonry walls to each other and to columns, roofs, and floors

are shown in figures 6, 7s 8, 10, 11, 12, 13, 111 and 13

o

6 d „ Ratio of height or length of wall to wall thickness

The ratio of unsupported height to nominal thickness or

the ratio of unsupported length to nominal thickness (one or the other but not necessarily both) for load=bearing walls

should not exceed 20 if of solid concrete masonry units and

should not exceed I8 if of hollow concrete masonry units

o

Similarly, this ratio should not exceed 18 for walls of

hollow masonry Including cavity walls,, In computing the

ratio for cavity walls, the value for thickness should be

the sum of the nominal thicknesses of masonry in the inner

and outer wytheSo The air space is not included in the

thickness used for computing this ratiOo In walls composed

of different kinds or classes of units, the ratio of height

or length to thickness should not exceed that allowed for

the weakest of the combination of units

o

The unsupported height of piers should not exceed 10

times their least dimension provided that when hollow concrete units are used for isolated piers to support beams

or girders, their unsupported height shall not exceed

times their least dimension unless the cellular spaces are

“ 19 “
filled solidly with concrete or either Type A-1 or A-2

m or t ar o

6f . Thickness of single-wythe bearing walls

The rninirnum thickness of bearing walls built of a single

wythe of either hollow or of solid concrete masonry units

should be 8 in„ for walls less than 12 ft in height. For

walls over 12 ft in height; the minimum thickness should be

12 in. for the uppermost 35 ft in height and should be increased i| in. for each successive 35 ft or fraction thereof

measured downward from the top of the wall.

6g . Thickness of stiffened bearing walls of solid units

Where solid masonry bearing walls built of solid units

are stiffened at distances not greater than 12 ft apart by

masonry cross walls or by reinforced concrete floors, they

may be of 12 in. thickness for the uppermost 70 ft measured

downward for each successive 70 ft or fraction thereof.

6h o Thickness of cavity walls

Cavity walls, either bearing or nonbearing, may be

built of solid or of hollow concrete masonry units and

should not exceed 35 ft in height except that the height

of 10 in. thick cavity walls should not exceed 25 ft above

the supports of such walls. The facing and backing wythe

s

of cavity walls. The facing and backing wythe s of cavity

walls should have a minimum thickness of l-i- in. and the

cavity should be not less than 2 in. or more than 3 in.

in width.

6l o Thickness of nonbearing exterior walls

Nonbearing exterior single-wythe concrete masonry walls

may be 5 in. less in thickness than required for bearing

walls , except that the thickness should be not less than

8 in

.

20
6 j

o Thickness of nonbearing partitions

Nonbearing concrete masonry partitions may be I4. in, less

than required for bearing walls except that the thickness

should be not less than 1| in» The distance between lateral

supports of nonbearing partitions should not exceed 36 times

the actual thickness of the partition including plaster.

6k o Decrease in thickness

% Where cavity walls and walls of hollow units are decreased

in thickness j a course or courses of solid masonry should be

Interposed between the wall below and the thinner wall above,

or special units or construction should be used that will

adequately transmit the loads from the shells above to those

bel ow

,

61 , Thickness of foundation walls

Foundation walls should be of sufficient strength and

thickness to resist lateral pressures from adjacent earth and

to support their vertical loads without exceeding the allowable stresses. Foundation walls or their footings should

extend below the level of frost action and should be not less

in thickness than the walls immediately above them. Basement

and cellar foundation walls should be parged on all surfaces

in contact with the ground,

6m o Depth of foundation walls

Solid foundation walls of solid masonry units that do

not extend more than ^ ft, below the adjacent finished ground

level may be 8 in, in minimum thickness | cavity walls and

walls of hollow units that do not extend more than b, ft, below

the adjacent finished ground level, may be 10 in, and 8 in,,

respectively, in minimum thickness. Those depths may be increased to a maximum of 7 ft, when soil conditions warrant

such Increase, The total height of the foundation wall and

the wall supported should not exceed that permitted by these

requirements for 8 in, walls.

6n

,

in other than cavity walls

Walls may be of more than one unit in thickness and when

so built the wythes and units should be bonded as in Section

7olol, Section 7.1 o 2, or Section 7.2 of A[|.l,lo

60, Bonding of cavity walls

The facing and backing of cavity walls should be bonded

21 -
with 3/l6”lno diameter steel rods or metal ties of equivalent

stiffness embedded in the horizontal joints. There should be

one metal tie for not more than each l/2 sq^ ft, of wall

area. Ties in alternate courses should be staggered and the

maximum vertical distance between ties should not exceed l8

in,, and the maximum horizontal distance should not exceed

36 in. Rods bent to rectangular shape should be used with

hollow masonry units laid with the cells vertical, see figure

16 ; in other walls the ends of ties may be bent to 90 degree

angles to provide hooks not less, than 2 in. long. Additional

bonding ties should be provided at all openings, spaced not

more than 3 fto apart around the perimeter and within 12 in.

of the cpening. Ties should be of corrosion-resistant metal,

or should be coated with a corrosion-resistant metal, or other

approved protective coating.

6p intersectinf

At corners and intersections where one wall is needed

as lateral support for the others, the walls should be bonded

by one or more of the methods given below,

(a) Laying at least 50 percent of the units in a

true masonry bond at the intersection or corner.

(b) By the use of joint reinforcement or metal ties

at the intersection or corner,

( c) By the use of bond beams.

If an intersecting wall is 12 ft, or more in length, a control

joint is required at or near the intersection (see Section 5)

•

The control joint should preferably be placed a distance equal

to about one-half the story height from the intersection rather

than at the intersection. If the control joint is placed at

the Intersection, the walls should be connected with interlocking bond beams if lateral support is required. Regardless

of the location and use of control joints, interlocking bond

beams may be used to insure lateral support for a wall,

6q . Bonding of enclosure walls to columns

Methods of bonding nonbearing concrete masonry enclosure

walls to steel columns and to concrete frame construction

(for lateral support) are illustrated in figures 10, 11, and

12, Walls between concrete columns should preferably be

anchored to the sides of the columns as in figure 10, In

spandrel beam constructions the tops of the walls may be

keyed to the bottoms of the spandrel with mortar. Since

- 22 -
the top of the walls may shrink from the bottom of the spandrel^ it may be better to anchor the walls to the colnmns and

provide a reglet to prevent rain penetration as shown in

figure 11, When the roof framing is supported on steel columns and the columns are needed to provide lateral support

for the walls, the method of anchoring the walls to the

columns may be as shown in figure 12. Bond beams may be

used at the anchor courses (figure 12) to increase the lateral

stiffness of the walls,

6r . Reinforced masonry

Where desirable, concrete masonry may be designed and

built to sustain bending and compressive load producing tensile stresses and compressive stresses higher than those permitted in Section 6a, This may be done by the proper use of

steel reinforcement and grout in the masonry. Such reinforcement, if used, should be in addition to the use of joint

reinforcement to control shrinkage cracking, discussed in

Section 5. Codes and specifications for the design and construction of reinforced masonry, other than those pertaining

to seismic design, are not widely available in printed form.

However, an American Standard Building Code Requirement for

Reinforced Masonry, A[i.l,2, is uhder consideration and may

become available at some future date,

6s , Wall openings

In general, openings in exterior load bearing concrete

masonry walls should be located so one continuous bond beam

may serve as a lintel for all openings. This may require

transoms for doors and a resection of window sizes. Wherever possible window heads should be located under a spandrel beam or under the top level bond beam in a story

height. The jambs, sills, and lintels at openings in concrete masonry walls may be of reinforced concrete. Ordinarily, the precast concrete, poured concrete, or the filled

masonry 'unit lintel is the only reinforced structural element

required at wall openings , Lintels should be designed for

shear and moment and should be of sufficient stiffness to

carry the superimposed load without deflection of more than

1/360 of the clear span. Information on the design of lintels in concrete masonry has been prepared and published by

the National Concrete Masonry Association, The minimum

length of bearing for simply supported lintels should be

as shown in figure 2, The use of control joints at wall

openings should not entail or require that slip joints or

unbonded bearing surfaces be used under one or both ends of

a lintel. Steel door and v/indow frames at openings should

not be in direct contact with the masonry or the lintel at

- 23
the top of the opening unless the frame is capable of supporting the loads that may be placed upon it as a result of

shrinkage of the masonry, without excessive deflection and

warping of the frame or cracking of the masonry. Typical details for window and door framing are shown in figures 17, l8,

19 and 20.

Concrete masonry should be of modular design based on

a [{.-in. module. The module should preferably be 8 in. but

a L|.-in. module may be used and may simplify the determination

of length of bearing under a lintel. standards for

modular design are A62„l - 19^5 and A62.3 - 19i|8.

6u . Drainage of walls

In cavity walls, the bottom of the cavity should be kept

clear of mortar droppings during construction. Flashings and

weep holes should be placed at the bottom and over openings

of cavity walls (Figure l6)

»

Flashings should extend over

the full length of lintels and over bond beams ard solid

sections of the wall below the top course. Flashings should

be rra de from hot-rolled copper sheet of 10 oz, weight having

a thickness of 0,013 to 0,017 in,, inclusive. The copper

sheets should comply with the requirements of Federal Specification QQ“C~576<, The flashing strips should be lapped 3

in. at the ends. The laps should be filled an_d sealed with

bituminous plastic cement meeting the requirements of Federal

Specification SS-C-153, type 1, Weep holes should be placed

at the bottom of vertical joints over flashings at intervals

not exceeding 32 in. The area of the weep holes should not

be smaller than that of 3/8 in, in diameter holes. The weep

holes may be formed by the use of rubber tubing, withdrawn

after the wall 1 s completed.

Masonry walls in locations where they may be exposed to

high winds during erection should not be built higher than 10

times their thickness unless adequately braced or until provision is made for the prompt installation of permanent

bracing at the floor or roof level immediately above the story

under construction. Back fill should not be placed against

foundation walls until they have been braced to withstand the

horizontal pressure.

7. ERECTION

7a. Bracinj :;o resist lateral loads

- 2I| -
7b , Wetting

Concrete masonry units should not be wetted before laying

and their moisture content should not exceed that specified

in Section 3d.

7c . Joint reinforcement

Joint reinforcement which has been bent or damaged in

handling should not be used until after it has been straightened and placed in good condition.

7d , Protection against freezing

Masonry should be protected against freezing for at least

i|8 hrs. after being laid. Unless adequate precautions against

freezing are taken, no masonry should be laid when the temperature is below 32 °P on a rising temperature, or below L(.0°F on

a falling temperature, at the point where the work is in progress. The laying of masonry should not proceed on frozen

material

.

7e

At the conclusion of the masonry work, mortar projecting

from the wall faces should be cut away. All scaffolding equipment, surplus materials and debris should be removed from the

finished structure.

8. FAINTING

Portland cement-water paints or grouts should be used as

base coats on the exterior faces of all above-grade concretemasonry walls that are to be painted. The grouts should be

used on rough- textured masonry surfaces and the paints should

be used on smooth surfaces. The base coats may be applied at

any suitable time after completion of the walls. There are

certain advantages in favor of early and of late applications.

An early application tends to protect the masonry against

saturation by heavy and long continued wind-driven rains,

thereby preventing an immediate moisture expansion and a later shrinkage of the masonry. A late application tends

to seal and fill shrinkage cracks which have developed in

the masonry since its completion. Pneumatically applied

coatings of suitable cementitious materials may be used as

alternate base coats instead of portland cement paints and

grouts, see section 8d.

8 a , Base coats on r ough-textured walls

Portland cement grouts used as base coats on rough-textured walls should be either of the two kinds listed below:

- 25 -
(1) Job mixed grout corxtalning i|0 to 50 percent of

either white or gray portland cement an.d 60 to

50 percent of a suitable sand aggregate. The

sand aggregate should pass a Noo 20 sieve and

should otherwise be suitable for use as a concrete or masonry mortar aggregate,

(2) A paint meeting the requirements of Federal

Specification TT-P-21, type II, class B,

8b o Base coats on smooth-textured walls

Portland cement paints used as base coats on smoothtextured walls should be either of the. two kinds listed

below;

(1) Either white or gray portlan.d cement,

(2) A paint meeting the requirements of Federal

Specification TT-P-21, type II, class A,

8 c , Application of base coats

Before applying the base coat, the masonry should be

clean, and all cracks or openings in the wall facing that are

larger than l/l 6 in, in width or diameter should be filled

with mortar or grout. The masonry should have been wetted

and should be in a damp condition but without water showing

on the surface at the time the base coat is applied. Paints

and grouts should be applied by vigorous scrubbing with brushes having stiff-fiber bristles. The base coat should be

cured by light wetting at least twice per day for two days

after application. In general, application of the base coats

should follow the recommendations in ACI Standard 616-14-9 (reprint title 14. 6 , 1 ), "Recommended Practice for the Application

of Portland Cement Paint to Concrete Surfaces,"

8 d, Pneumatically applied cementitious base coats

An optional method of applying a cementitious base coat

in lieu of that specified above may be selected by the contractor, This consists of coating the surfaces with a mortar

consisting of portland cement, a water-repellent admixture,

and selected aggregates (excluding soft aggregates), applied

pneumatically by spray in one continuous operation to a

minimum thickness of I/8 in, beyond the nominal face of the

wall. Application shall be by a firm specializing in this

type of coating. Specifications for similar but thicker

cementitious facings are given in ACI Standard 805"5l?

"Recommended Practice for the Application of Mortar by

Pneumatic Pressure," (ACI Reprint Title l4

. 7 -I]. 8 )

,

26 -
8 e „ Finish coats

Finish coats should be of cement-water paint and should

be applied after the base coat has hardened „ The base coat

provides protection against the leakage of wind-driven rain,

and the time of application of the finish coats should be

selected so that weather conditions are suitable „ The finish

coats may be expected to seal fine hairline cracks and crazing in the base coats resulting from further drying of the

masonry, and application of the finish coats may therefore be

delayed until such drying may have occurred

„

8 f 0 Calking

Calking materials should comply with the requirements of

Federal Specification TT-C-598 (gun application) „ Application

of calking or of the stripping used as a substitute for calking

should be made after the painting has been completed,

9o SAMPLING AND TESTING CONCRETE MASOhRY UhlTS

Except as modified herein methods of sampling and testing

concrete masonry units should be in accordance with ASTM

Standard Cll|.0-52o

9a, selection of specimens

At least 10 days should be allowed for completion of the

drying shrinkage tests. Five individual units should be

selected from each lot of 10,000 units or fraction thereof

and 10 individual units from each lot of more than 10,000 and

less than 100 , QOO' units y For lots of more than 100,000 units,

5 individual units should be selected from each ^0^000 units

or fraction thereof contained in the lot. Additional specimens may be taken at the discretion of the Contracting

Officer, Units previously subjected to any other tests which

Involve their being subjected to temperatures exceeding l50°F

should not be used in the drying shrinkage test. At the discretion of the Contracting Officer, bars not less than 2 in,

in width and equal in length to the height of the full-sized

units may be cut from the units selected for use in the drying

shrinkage test.

The specimens should be prepared with suitable contacts

for use in measuring their changes in length to the nearest

OoOOOl percent. They should then be submerged in water at

73° 1 for 24 hr „ following which the initial length

should be procured. The specimens should then be dried in

27

/
a ventilated oven at 230° ± 5° F for [[.8 hr, after which they

should be stored for at least l8 hr in a vapor- tight container at 73° ± 5° P o Their lengths should then be- remeasured.

The percentage drying shrinkage should be calculated as 100

( Lw-Ld )

( Lw ) where Lw = wet length and

Ld = dry length

Drying shrinkage tests on concrete masonry units are described

in a progress repqrt of ACT Committee 716, Reprint title

k9-^3, published in the April 1953 Journal of the American

Concrete Institute,

9c , Periodical check on moisture c.ontent

Representative samples should be taken from the on-site

stock piles for check of moisture content. Two such checks

should be made per week during construction of the walls.

Each sample should consist of at least 3 blocks. The tests

should be perform.ed in accordance with ASTM Standard C 114. 0 - 52 and the units should be selected from the stock piles in

current use, at the time of test. Units which fail to meet

the moisture content limitation should be rejected and should

not be used until properly dried, see sections 3d and 3®

»

9d , Staining test for aggregate

The test for staining should follow the procedure in the

proposed Tentative Specifications for Lightweight Aggregate

for Concrete Masonry Units (see sections 5 and 7 of the

tentative specifications dated March 5? 1953? ASTM Committee

C-9) .

9e. Test

Three whole concrete masonry units or pieces of the face

shells from the three concrete masonry units may be selected

for the test. When pieces of the face shells are used their

surface area should total at least L|.0 sq in, for each unit

and the smallest length or width of the pieces should not

be less than 3 in. The selected specimens should be autoclaved in accordance with the Standard Method of Tests for

Autoclave Expansion of portland cen^ent, ASTM designation

Cl5l. The specimens should be placed above the water in the

autoclave and racked to permit the free circulation of steam

around them. If the heat capacity of the specimens is greater

than that of the specimens normally used in an autoclave,

the time required to reach maximum pressure in the autoclave and to cool the specimens may be increased. However,

the duration of exposure at maximum pressure should not be less

than 2 hours. Subsequent to the autoclave exposure, visual

28 -
inspection of the specirriens should not disclose any surface

popouts in them„ Evidence of surface popouts or severe

disintegration (breaking) of the specimens should result in

rejection of the units they represent. This test may also be

helpful in disclosing staining of the units.

29

<NBS>

FIG. I TYPICAL BOND BEAM UNITS





FILL

THIS

CELL- —-r

^MORTAR JOINT ^CONTROL JOINT

NON- BEARING

PARTITION*

J[

NDUSTRIAL

2"X2" MESH

ZINC-COATED WIRE CLOTH,

NO. 14 WIRE. (WT. I LBySQ.FT.)

PLAN

X

UJ ^ .* . '.1

.

HEIGHT OF WALL NON BEARING

PARTITION

MORTAR JOINT I^CONTROL JOINT

E 3| ±J_X8

WELDED Wire FAiRiC, CUT FROM FLAT

STRIP JOINT REINFORCEMENT

OPTIONAL SELECTION OF METAL TIES

MORTAR JOINT

I

HEIGHT OF WALL i^cONTRO . JOINT

METAL TIES

EVERY OTHERI COURS-E

lOR WALL

ELEVATION OF INTERIOR WALL

OR PARTITION

FIG. 7 TYPICAL WALL AND PARTITION INTERSECTION <i0>

USE FACTORY MADE CORNER SECTIONS OR CUT FROM

WELDED WIRE-FABRIC OF 6 IN. MESH , MINIMUM SIZE

N0.8 AMERICAN STANDARD STEEL WIRE GAGE

— ’

^ZINC-COATED CROSS WIRES, MIN. SIZE N9 I2A.S.

.4 a W.6AGE. MAX. SPACING 6 IN. FOR SMOOTH ^

LONGITUDINAL WIRE, IS IN. FOR DEFORMED

LONGITUDINAL WIRE.

.55*Af^R0J<.

SP, SMOOTH OR DEFORMED LONGITUDINAL WIRES ^ MINIMUM SIZE N98 A.S.a W.6AGE

o

a.

>< r“

SECTION B-B, FULL SIZE

DEFORMED WIRE ONLY, MINIMUM SIZE N98 A.S.

a W. GAGE

note: selection of type of

REINFORCEMENT SHOWN IN SECTIONS

A-A AND i-8JS OPTIONAL

-JOINT RE1NFORCEMENT.STRAIGHT FLAT STRIPS.

J.EN6TMS 10 TO 24 FEET

FIG. 9 PLAN AND DETAIL OF JOINT REINFORCEMENT SHOWING

LAPPED SPLICES

MORTAR

JOINT
PLAN OF REINFORCED CONCRETE COLUMN SHOWING

DOVETAIL TIES.

PLAN OF REINFORCED CONCRETE COLUMN HAVING

V-SHAPED DEPRESSIONS.

! FIG.IO CONCRETE FRAME, COLUMN AND WALL INTERSECTION. <@>

5 1

I


DETAIL OF INTERSECTION OF ROOF AND WALL OF ONE-STORY

STHUCTUeE HAVING BEARING WALL AND WOOD ROOF

note: roof shall be insulated on top surface

FILL WITH MORTAR2

3

- -REINFORCED CONCRETE

ROOF SLAB AND BEAM

CONSTRUCTION

MORTAR JOINTS

•CONCRETE MASONRY NON-LOAD

BEARING WALLS

DETAIL OF INTERSECTION OF ROOF AND WALL HAVING NONBEARING WALL STRUCTURE

FIG. 13 ROOF AND WALL INTERSECTIONS

<HB>

FI6.I5 TYPICAL WALL SECTION AT WOOD JOIST FLOOR.
1—ll «— — « _ :rz IT B ETA L TIES SPACED 3Z“CTRS.

U 1 B r

pa LACED'IN ALTERNATE

ED JOINTS E-^ i 7TZ rr~

]

/WEEP HOLES IN ALTERNATE

VERTICAL Jl JOINTS -*.)!

3 ?

ELEVATION OF CAVITY WALL

NONL CORROSIVE

METAL

TIES

3^"

*^8

CONTINUOUS

METAL

FLASHING

FLOOR

*6 A. S. a WIRE GAGE, 0IA.«.I92IN.

10 OZS^FPER FLASNIN#

FIG.I6 MASONRY CAVltY WALL <@>


note: anchorage of door frame to floor

CEILING—^ AND CEILING IS OPTIONAL.

PRLCAST LINTELS

ARi: OPTIONAL

'JOINT REINFORCING TO EXTEND 30")

BEYOND JAMB LINE.—

>ANCHOR

CORES FILLED SOLID

FROM FLOOR TO

DOOR HEAD

ELEVATION

-H"-

Hi

SOLID GROUTING

AND MORTAR

^FORMED METAL

DOOR JAMB

SOLID GROUTED, RODDED

PARTICULARLY AT ANCHOR

-rrr^rrrr^

J. •

I* 4i -1

- ^

<» <i ^ <1

• ,•

4j

: • . . .......

<7 <) - J

lO

PLAN OF DOOR JAMB

‘JOINT REINFORCEMENT

SECTION OF DOOR HEAD

FIG. 19 DETAIL OF TYPICAL METAL DOOR FRAME

IN PARTITION.
ADJUSTABLE "t''ANCHOR

SOLID GROUT

METAL ANCHOR

r;

" ^

.

“^SOLID GROUTED, RODDED

PARTICULARLY AT ANCHOR

PLAN

V CONCRETE MASONRY

PARTITION

SOLID GROUT-

- <0 ! •©- • "1 UJ£

<

1

1 4 « <•

0 d>

>

_J L. y;

•*l

u

* cA

3 ^ 1

SOLID GROUTED, RODDED

PARTICULARLY AT ANCHOR

PLAN

UNDERWRITER'S TYPE

ANCHOR

FIG. 20 OPTIONAL TYPES OF TYPICAL JAMB ANCHORS FOR

METAL DOOR FRAMES IN INTERIOR PARTITIONS.<^
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

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Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

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journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

complete papers reporting technical investigations; the Technical News Bulletin, which presents

summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions,

which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications.

Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.00). Information on calibration services and fees can be

found in NBS Circular 483, Testing by the National Bureau of Standards (25 cents). Both are

available from the Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.