Development of a Procedure for Temperature Correction of Backcalculated AC Modulus (0-1863-1)

The falling weight deflectometer (FWD) is commonly used in Texas for pavement evaluation and design purposes. Typically, measurements are made on a given date so that the data reflect the environmental conditions prevailing during the time of measurement. For pavement applications, the backcalculated asphalt concrete modulus needs to be adjusted or corrected to reference or standard conditions of temperature and loading frequency. This report documents the development of a procedure for adjusting backcalculated asphalt concrete (AC) moduli to user-prescribed reference pavement temperatures. In this way, seasonal variations in AC modulus may be predicted for pavement evaluation and design purposes. In the development of the procedure, researchers analyzed FWD and pavement temperature data collected at Seasonal Monitoring Program sites in Texas, New Mexico, and Oklahoma and at two test sections located at the Riverside Campus of Texas A&M University. Pavement temperature data were used to evaluate the BELLS2 equation. This work resulted in an alternative equation for predicting pavement temperatures. Researchers used the MODULUS program to backcalculate pavement layer moduli from the FWD data collected at different times. The backcalculated AC moduli were subsequently used to evaluate a number of temperature correction methods. This report presents the findings from this evaluation along with recommendations with respect to developing an automated method for modulus temperature correction.