Analysis of Mechanical Properties and Pore Structure of Mortar Prepared from Municipal Solid Waste Incineration Slag

Abstract

Abstract The disposal of a large amount of bottom ash generated from the incineration of municipal solid waste has become the focus of research in solid waste and environmentalism. Using municipal solid waste incineration bottom ash (MSWI BA) to prepare mortar can not only solve the problem of insufficient natural river sand resources, but also play a role in treating a large amount of MSWI BA to alleviate urban pressures. In this study, macroscopic properties of mortar were systematically investigated by rheological, mechanical, and drying shrinkage tests, and the influence of MSWI BA on the internal pore structure and interfacial transition zone of mortar has been analyzed by mercury intrusion porosimetry (MIP), scanning electron microscope (SEM) and back scattered electron imaging (BSE). The results show that the rheological model of fresh mortar mixed with MSWI BA as fine aggregate is more consistent with the modified Bingham model, and its plastic viscosity decreases and then increases with the increase of MSWI BA, while the yield stress shows an increasing trend. The compressive strength and splitting tensile strength of mortar decrease with the increase of MSWI BA; the smaller the water-cement ratio and aggregate-binder ratio, the greater the strength loss. The incorporation of MSWI BA improves the flexural strength and compression-flexure ratio of M5/M10 mortar, and the splitting tensile strength of M5 mortar at 28 days is increased by 30 % with 20 % MSWI BA. Additionally, the incorporation of MSWI BA reduces the drying shrinkage properties of mortar and improves the volume stability. At the same time, it increases the number of pores above 50 nm inside the mortar and the content of ettringite at the interface.