VAA Virginia Asphalt Fall/Winter 2020

VAASPHALT.ORG 17 configured to remove the seating load, and the LVDT installation and range should be checked. Another issue with the displacement measurement is shown in Figure 2(d). It appears that the LVDTmay not have been installed or zeroed/initialized properly so that measure- ments were not collected as the test started. Figure 2(e) presents a load-displacement curve that complies with test requirements, although the test was performed using a non-linear loading rate. This demonstrates why evaluating both the load-displacement and displace- ment-time data are important. If the loading rate is non-compliant, the equipment does not meet the test requirements andmay need troubleshooting or maintenance. While small deviations from 50±2 mm/min have not appeared to significantly affect calculated CTindex values for data collected to date, more work is necessary to validate the acceptable range of loading rates. Ongoing data quality checks are essential to implement with the use of performance testing. Non-compliance in test data can lead to incorrect CTindex values that do not describe the actual material performance— resulting in unnecessary redesigns or rejectedmaterials. The next step in addressing overall data quality is checking that test results fall within acceptable precision estimates, but that is another discussion. (c) Errors in test setup and data acquisition. A seating load is applied at the beginning of the test and displacement measurements stop before the end load is reached. (d) Synchronization issue with displacement—the load is recorded but displacement lags. LVDT may not be installed or zeroed/initialized properly. (e) Load-displacement curve is compliant; however, the loading rate is less than specified and changes during the course of the test. ROUND ROBIN PHASE 1