Viscoelastic Model and Stress Relaxation Evaluation of Pavement Crack Sealants at Low Temperature

Sealants exist under conditions of great strain for extended periods in winter; their viscoelastic characteristics at low temperature can play a critical role in preventing adhesion failure. Two types of hot-poured sealants and two types of silicone sealants are selected for extension tests with reference to a standard bond test. Stress relaxation tests are conducted when a 50% strain is reached. The test data are fitted with extension and stress relaxation with a standard linear solid model to obtain a fitted extension-stress relaxation equation, which is used to obtain viscoelastic characteristic parameters of the model. The fitted result shows that the standard linear solid model can fit the viscoelastic performance at low sealant temperature. Two viscoelastic characteristic parameters of the maximum relaxation ratio and relaxation time can be used to evaluate the stress relaxation ability of different sealants, but the fitting process of the viscoelastic model is more complicated. Therefore a simple stress relaxation index is defined. Results of the evaluation with this index are consistent with results with the maximum relaxation ratio and relaxation time, which indicates that this index is applicable to the evaluation of stress relaxation of sealants and features better practicability and operability. The evaluation of the stress relaxation shows that the relaxation performance of hot-poured sealants at low temperature is better than that of silicon sealants. Therefore hot-poured sealants may be more applicable for use in areas with long-term low temperatures in winter. (C) 2017 American Society of Civil Engineers.