Effect of sample setting time on experimental evaluation of hot mix asphalt

Hot mix asphalt (HMA) samples tested randomly after molding might lead to misleading performance prediction of asphalt mixture in laboratory. This paper aims to investigate how the sample setting time affects the laboratory evaluation results for HMA mixes. Nine kinds of test procedures were employed to analyze the performance evolution of asphalt mixture AC-13 for varying sample setting times ranging from 1 day to 90 days. Test results showed that oxidative aging and emission behavior of volatile organic compounds from asphalt might be the causes for stiffness effect of lab-molded samples, and consequently leads to test results change. With the setting time prolonging, permanent deformation resistance of asphalt mixture was improved, while the anti-cracking and fatigue properties were degraded. Noticeable variation of test results occurred during the initial week after HMA sample molded in laboratory. Moreover, sample setting time effect on result evolution of different test methods were relatively diverse due to their particular test procedures and objectives. In consideration of field performance of asphalt mixture, more laboratory test procedures and HMA mixes are recommended to specify the reasonable sample setting time for different test methods.