Correction Factor of In Situ Back-Calculated Modulus and Laboratory Dynamic Modulus for Pavement Asphalt Layer

Based on a perpetual pavement test road, FWD and laboratory dynamic modulus test was conducted, relation between back-calculated modulus and pavement temperature was analyzed, equivalent dynamic modulus of HMA layer based on in-situ pavement temperature and laboratory dynamic modulus was introduced and characteristics of back-calculated modulus and HMA layer equivalent dynamic modulus was compared. Temperature correction factor models for back-calculated modulus and correction factor models between back-calculated modulus and HMA layer equivalent dynamic modulus was developed. The research shows that both back-calculation modulus and equivalent dynamic modulus of HMA layer decrease with temperature increases. Back-calculated modulus is bigger than equivalent dynamic modulus at low temperature, equal to equivalent dynamic modulus at room temperature and less than equivalent dynamic modulus at high temperature. The temperature range is 10–25°C when correction factory K is equal or near to 1.