No. 542 June 2011 

Field-Use Round Determinate Panel Test System 

Objective 

To develop a portable field-use testing system for 

conducting ASTM-1550-05 round determinate panel tests. The 

test system can be used at the mine site to obtain shotcrete 

toughness strengths that are required for determining the support 

requirements for mine openings, minimizing falls of ground, 

and reducing mine roof-fall incidents (Figures 1 and 4). 

 Figure 1. Portable round determinate panel test system. 

Background 

When shotcrete is used as part of a ground support system in 

mining, it is important to know the placed strength of the 

shotcrete. The round determinate panel test (RDPT) was 

developed to quantify the resistance to tensile failure and 

toughness of fiber-reinforced shotcrete. The tension cracks 

produced by the RDPT represent the failure type observed in 

underground tunneling and mining. There are two design values 

obtained from the RDPT, the load profile and the energy. Both 

of these values are used when designing ground control for 

underground openings. While many methods have been tested 

for measuring strengths, RDPT is the preferred method for 

directly measuring determinate breaks and providing resultant 

toughness. 

Operating the Portable Round Determinate 

Panel Test System 

Round panel samples are formed by spraying shotcrete into 

75 x 800-mm (3 x 31.5-in) mold rings. The upper surface of 

each panel is leveled with a screed to a flatness tolerance of 

within 5 mm (0.2 in). Each sample must measure between 70 to 

90-mm (2.75 to 3.5-in) high and 750 to 850-mm (29.5 to 33.5-

in) in diameter, with correction factors available for variances. 

Three samples are usually made for each test interval, and tests 

are typically conducted after the shotcrete has cured for 7, 14, 

and 28 days. 

The portable RDPT system is a self-contained, closed-loop, 

servo-controlled, stiff-frame press. To conduct a test, a cured 

sample is positioned on three support pins centered below the 

test system’s ram. After the ram is lowered to a position just 

above the sample, an automated test cycle is initiated by 

depressing the green start button, which initiates the test and 

also starts the data acquisition system. The ram is set at a 

stroke rate of 4.00 mm/min (0.16 in/min) as per ASTM 

specifications; a full test stroke is 45 mm (1.77 in). During the 

test, the operator observes the sample for the development of 

three tension cracks (Figure 2). 

Figure 2. Shotcrete test specimen. (A) Three determinate tension cracks 

as produced during a test. (B) A typical panel cross section showing 

fibers.

The cracks usually develop at 

less than 5 mm (0.2 in) of ram displacement. After a full test 

stroke, the press head automatically retracts to unload the 

sample. The test specimen is then measured in 10 spots for 

thickness, and a relative fiber count is conducted on the broken 

face of the sample (Figure 2). 
Data for load and displacement is gathered using an Eaton 

data logger. Typical round determinate panel test results 

comparing shotcrete load and energy versus displacement are 

shown in Figure 3. 

 Figure 3. Typical round determinate panel test results. 

 Figure 4. Schematic of field-use RDPT system. 

Design Features 

Mobile with built-in controller 

Compact and easy to stow or transport underground 

Full range of motion 

Operator located at the test site location 

Fully automated test cycles 

Power choices: 110 V or DC→AC inverter at site

Specifications

Press 

Capacity 108 kN 24,000 lbf

Height 185 cm 73 in

Width 150 cm 59 in 

Depth 84 cm 33 in 

Speed – test 4.0 mm/min 0.16 in/min

Speed – jog 45.7 mm/min 1.8 in/min

Drive system Ball screw

Control Closed-loop servo

Data System Eaton Controls

Control Box

Height 41 cm 16 in 

Width 23 cm 9 in 

Depth 41 cm 16 in 

Power 110 VAC

Operating system Eaton Controls

Output ± 0–5 Volt signal

For More Information 

For more information on the RDPT system, contact Lewis 

Martin at LMartin@cdc.gov 509-354-8077, or the Health 

Communications Coordinator (OMSHR@cdc.gov), NIOSH 

Office of Mine Safety and Health Research, P.O. Box 18070, 

Pittsburgh, PA 15236-0070. 

To receive NIOSH documents or for more information 

about occupational safety and health topics, contact: 1-800-

CDC-INFO (1-800-232-4636), 1-888-232-6348 (TTY), email: cdcinfo@cdc.gov, or visit the NIOSH Web site at 

http://www.cdc.gov/niosh

Mention of any company name or product does not 

constitute endorsement by the National Institute 

for Occupational Safety and Health.

DHHS (NIOSH) Publication No. 2011–187