Evaluating the recycled pavement performance and layer moduli at variable temperature by nondestructive tests

This study has focused on the response of cold recycled asphalt layer with bitumen emulsion and cement using the falling weight deflectometer (FWD) and laboratory test at variable temperature conditions. In this regard, Semnan–Damghan highway has been considered as the case study. Nondestructive tests including FWD and ground penetrating radar (GPR) were performed to estimate the layers elastic moduli and thickness. The backcalculation analysis was accomplished using the ELMOD software. Also, a backcalculation analysis method has been proposed by implementing a code by BASIC programming language. Destructive tests were performed by sampling in some of the studied stations. Indirect tensile stiffness modulus and triaxial tests were accomplished to measure the bound and unbound layer moduli in the laboratory, respectively. Since the recycled layer contained two binders including bitumen emulsion and cement, the dependency of its behaviour to temperature was to some extent different from hot mix asphalt. At the final stage, the temperature correction coefficients were determined for the materials studied in the current research study. The precision of results obtained from these coefficients were compared with those presented in the literature. Accordingly, the presented correction coefficients resulted in a more precise moduli estimation than previous temperature correction models.