Study on microstructure, rheology and thermal stability of cement epoxy asphalt mortar multiphase materials

The effect of modified epoxy asphalt emulsion on the fluidity and microstructure of fresh cement modified asphalt emulsion binder was assessed. Various analytical instruments, such as X-ray diffraction, scanning electron microscopy and environmental scanning electron microscopy, Brookfield viscometer and differential scanning calorimetry were used to investigate the microstructure formation and development of cement epoxy asphalt emulsion, as well as the rheological properties, microstructure and thermal stability of cement epoxy asphalt mortar (CEAM). The results indicated that addition of asphalt emulsion and epoxy resin to cement paste greatly increased fluidity and improved capability of fluidity retention, while delaying the cement hydrating process. The amount of modified epoxy asphalt emulsion and epoxy resin introduced into the cement paste generally correlated with the length of the cement hydration induction period. The microstructure formation and development of CEAM consisted of several stages, including attachment of modified epoxy asphalt to cement particles, emulsion splitting and cement hydration thereby. Within CEAM, modified epoxy asphalt formed a macromolecular gel network structure, which interpenetrated with cement hydration products to establish an organic–inorganic composite structure. Fresh CEAM exhibited good fluidity within 45 min, and also had better thermal stability than cement asphalt mortar at elevated temperatures.