Effects of pre-curing temperatures on the mechanical properties and microstructural development of impregnated municipal solid waste incineration bottom ash mortar

Abstract

Environmental pollution and land resource waste caused by municipal solid waste incineration bottom ash (MSWIBA) have attracted considerable attention. The use of MSWIBA as a gelling material is a promising treatment method, but temperature significantly influences its mechanical properties and microstructural development as a gelling material. In this study, the effects of pre-curing temperature on the mechanical strength and microstructural development of Na2CO3-impregnated MSWIBA mortar were investigated to improve the performance of MSWIBA and utilisation rate of bottom ash. The compressive and flexural strengths of the mortars were tested. X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were used to analyse the microstructure of the sample from the fracture surface of the mortar. The results indicated that the high-temperature pre-curing conditions stimulated the early hydration reaction of the mortar, accelerated the hydration process, and improved the early compressive strength. However, the early hydration products are formed quickly, and the uneven accumulation hinders the development of strength in the middle and late stages. The variation in the pre-curing temperature does not change the type of hydration products but affects the number of hydration products. High-temperature pre-curing conditions accelerate the transformation of hydration products and affect the microstructure of hydration products. This research provides theoretical support to improve the performance of MSWIBA, enhance the utilisation of bottom ash, and reduce environmental pollution.