Determination of Creep Compliance and Tensile Strength of Hot-Mix ...

dummy specimen temperature was again within ±0.5°C of the targettemperature.4. Once testing is completed at -20°C, repeat steps 1 through 3 at 0°C and thenagain at -10°C, all with the same three specimens.Thus, the same three specimens were tested at all temperatures in the followingorder: 1, 2, 3 (at -20°C), 3, 2, 1 (at 0°C), then 1, 2, 3 (at -10°C). On average, it tookabout 12 hours to perform the creep testing for one set of replicates. Most of thattime was spent waiting for the temperature of the dummy specimen (as indicated bythe type K thermocouple) to stabilize at the desired test temperature, ±0.5°C.25001900 + 2%200015001900 - 2%Load (lbf)100050000 20 40 60 80 100 120 140Time (seconds)Figure 4: Typical Load vs Time PlotThe use of a thermocouple-instrumented dummy specimen to determine testspecimen temperatures was a deviation from T 322-07. Section 11.3 states to“lower the temperature of the environmental chamber to the test temperature and,once the test temperature ±0.5°C is achieved, allow each specimen to remain at thetest temperature from 3 ± 1 hours prior to testing.” The problem with the methodspecified in T 322-07 is that the door to the chamber is open for approximately 5minutes while the adapters/extensometers are being transferred to the nextspecimen, thus the chamber and the specimens warm up. Upon closing the doorand turning the chamber back on, the chamber will come back to test temperaturemuch faster than the specimens; i.e. there is no guarantee that the instrumented test9