UFC 3-260-02
30 June 2001
are attached over areas between the aggregate faces). Wire the strain gauges as required in
paragraph G-5 and attach suitable lead wires and connectors.
H-7. PROCEDURE. The following testing procedure is recommended:
a. Place test specimens in a controlled temperature cabinet, and bring them to the specified
test temperature. A dummy specimen with a thermocouple in the center can be used to determine
when the desired test temperature is reached.
b. Place a specimen in the loading apparatus, and connect the strain gage wires to the
measurement system. Put the hardened steel disk on top of the specimen and center both under
the loading apparatus. Adjust and balance the electronic measuring system as necessary.
c. Apply the haversine loading to the specimen without impact and with loads varying
between (0 and 35 psi) for each load application for a minimum of 30 seconds and not exceeding
45 seconds at temperature of 4.5, 21, and 37.8 degrees Celsius (40, 70, and 100 degrees
Fahrenheit) and at loading frequencies of 2 hertz for taxiway design and 10 hertz for runway
design. If excessive deformation (greater than 2,500 microunits of strain) occurs, reduce the
maximum loading stress level to 0.12 MPa (17.5 psi).
d. Test three specimens at each temperature and frequency condition twice. Start at the
lowest temperature and repeat the test at the next highest temperature. Bring the specimens to
the specified test temperature before each test is commenced.
e. Monitor both the loading stress and the axial strain during the test. Increase the recorder
chart speed so that one cycle covers 25 to 50 millimeters of chart paper for five to ten
repetitions before the end of the test.
f. Complete the loading for each test within 2 minutes from the time specimens are removed
from the temperature control cabinet. The 2-minute testing time limit is waived if loading is
conducted within a temperature control cabinet meeting requirements in paragraph H-5.
H-8. CALCULATIONS. Measure the average amplitude of the load and the strain over the last
three loading cycles to the nearest 1/2 millimeter. Calculate the loading stress Fo using the
equation
F
(H-1)
where
H1 = measured height of load, millimeters (inches)
H2 = measured chart height, millimeters (inches)
L = full-scale load amplitude determined by settings on the recording equipment, Newtons
(pounds)
H-2
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