Feasibility of preparing self-compacting mortar via municipal solid waste incineration bottom ash: an experimental study

To date, incineration is the main method of municipal solid waste (MSW) disposal. Fly ash and bottom ash (BA) are generated in large amounts from municipal solid waste incineration (MSWI), but the disposal of incineration residues poses a significant challenge to large cities with limited landfill space. The feasibility of using MSWI-BA to replace natural sand in the preparation of self-compacting mortar (SCM) was investigated to realize the resource utilization of MSWI-BA. The changes in SCM regarding durability, mechanical properties and workability when MSWI-BA was added at varying ratios were explored in this study. In addition, the changes in SCM microstructure, dynamic modulus of elasticity (DME) and ultrasonic pulse velocity (UPV) under the impacts of MSWI-BA were investigated. Eventually, the environmental and economic effects of SCM were weighed via the material sustainability index. It was found that (1) there was a drop of 23.79-44.69% in the compressive strength of SCM and a drop of 12.22-30.99% in the flexural strength, due to the incorporation of MSWI-BA; (2) the drying shrinkage of SCM increased from 2.9 to 11.76%, and the chloride migration coefficient increased from 4.66 to 46.06%, due to the incorporation of MSWI-BA; (3) the production costs, carbon footprint and energy consumption of SCM could be reduced, due to the addition of MSWI-BA; and (4) SCM could satisfy the engineering requirements of durability, mechanical properties and workability. Therefore, MSWI-BA was found to be a feasible method for the production of SCM.