Preparation, characterization and repeated repair ability evaluation of asphalt-based crack sealant containing microencapsulated epoxy resin and curing agent

Abstract

In order to improve the repeated repair ability of asphalt-based crack sealants, two types of microcapsules were prepared and added into asphalt-based crack sealant. The epoxy resin and curing agent were microencapsulated by using interfacial polymerization method, and named as A-type and B-type microcapsules respectively. The effects of emulsifier content and core-wall ratio on the preparation of two types of microcapsules were analyzed, and SEM, FT-IR, TG-DSC, and FOM analyses were performed to study the microscopic features of microcapsules, including the particle size and size distribution, chemical components, morphological features, thermal stability as well as the dispersion of microcapsules in the sealant. Then, DSR tests were conducted with two-stage loading mode to evaluate the repeated repair ability of asphalt-based crack sealants with different dosages of microencapsulated epoxy resin and curing agent. The results show that the optimal emulsifier contents are 0.5% and 0.7% for the A-type and B-type microcapsules respectively, and the corresponding core-wall ratios are 1.3:1 and 1.1:1 respectively. The two types of microcapsules were successfully prepared with well-distributed particle sizes and sufficient thermal stability, which are be well dispersed in asphalt-based sealants. The repeated repair ability indexes were proposed based on DSR complex shear modulus and the corresponding loadings cycles. It is found that the repeated repair ability of composited sealants is obviously improved. The optimal dosage of two types of microcapsules are 3%, and a sufficient healing time is required for repairing crack due to the indispensable curing process of epoxy.