Experimental studies and microstructure analysis for rapid-hardening cement emulsified asphalt mortar

A cement emulsified asphalt mortar (CEAM) made with calcium sulfoaluminate cement was prepared and tested indoors, which has a relatively slight environmental impact compared with ordinary Portland cement. The effects of asphalt to cement (A/C) and water to cement (W/C) ratios on the performance of CEAM were systematically evaluated, such as the fresh properties, mechanical properties, volume deformation, temperature dependence, permeability, and frost resistance. Meanwhile, the microstructure images and void characteristics were also obtained by computed tomography technology and scanning electron microscope. The results indicated that with the increase of A/C ratio, the flow time, setting time, and air content of fresh CEAM increase, while the slump flow decreases. The fast-hardening CEAM has higher early strength, which decreases with the W/C and A/C ratios increasing. In addition, the A/C ratio also has a significant influence on the long-term performance of CEAM. High emulsified asphalt content will reduce shrinkage, temperature dependence, and impermeability, but will increase its frost resistance. In addition, different emulsified asphalt and cement contents have a significant effect on microstructure and pore characteristics of CEAM, which directly determines its macroscopic properties. This paper contributes to the structure formation of calcium sulfoaluminate CEAM and provides a reference scheme for the construction of track slabs in winter.