The impact of cold-bonded artificial lightweight aggregates produced by municipal solid waste incineration bottom ash (MSWIBA) replace natural aggregates on the mechanical, microscopic and environmental properties, durability of sustainable concrete

Abstract

Currently, most of the municipal waste is incinerated and then transported to landfills for disposal, which takes up a lot of land resources and causes safety problems due to the hazardous materials such as heavy metals in MSWIBA. Therefore, a novel and green recycling approach is urgent. Here, MSWIBA is recycled by manufacturing artificial light coarse aggregates (ALCAs) and used as coarse aggregates to partially replace natural aggregates (NAs) to design green concrete. In this work, ALCAs made of MSWIBA replaced NAs with different percentages (0%, 25%, 50%, 75% and 100%) to manufacture artificial lightweight coarse aggregate concrete (ALCAC). The influence of specific gravity, compressive strength, splitting strength, carbonization performance and micro properties of ALCAC were studied. It was observed that with an increase in the replacement rate of ALCAs, the specific gravity of ALCAC decreased by up to 12.1%, and the mechanical properties also declined. However, the compressive strength can still reach more than 30 MPa, and the splitting strength can reach more than 3.3 MPa. In addition, an increase in the ALCA content also led to an increase in the ALCAC matrix pores, and CO2 was more likely to invade the concrete interior, which increased the depth of concrete carbonization. The hydration products of ALCAC make the interface zones (ITZs) rougher, and the bonding effect in the ITZ area is significantly better than that of NAC. Compared with fly ash (FA) light aggregate concrete, ALCAC has lower energy consumption and CO2 emissions. This study provides insight into the recycling of MSWIBA and application of ALCAs for sustainable RC structures.