Valorisation of municipal solid waste incinerator bottom ash for the production of compressed stabilised earth blocks

Abstract

This research centres its attention on the valorisation of incinerator bottom ash derived from municipal solid waste with the aim of producing compressed stabilised earth blocks. Compressed stabilised earth blocks is prepared with 6–12% cement and 10–40% MSWIBA, whose performance is assessed in terms of strength and durability. This includes several properties of compressed stabilised earth blocks, including dry compressive strength, flexural strength, tensile strength, water absorption, wetting-drying cycle, ultrasonic pulse velocity and acid attack. The findings indicate that the inclusion of municipal solid waste incinerator bottom ash as a 20% replacement of soil enhances the compressive strength and ultrasonic pulse velocity of the blocks. Nevertheless, the excessive use of municipal solid waste incinerator bottom ash (beyond 20%) results in an augment of void content and a reduction in compressive strength. The results of the study suggest that the usage of municipal solid waste incinerator bottom ash in the blocks leads to the enhancement of their aesthetic qualities. The study employing scanning electron microscopy indicates an excessive quantity of ettringite crystals in the samples derived from ash of quantity beyond 20%. This is because these samples have higher porosity, which enables the acidic medium to penetrate samples easily and react with the cement hydration products. Hence, though showing less discolouration on the surface, these samples show a significant reduction of compressive strength at the end of the testing regime. Similar results were obtained for the wetting and drying test as well. Therefore, this study recommends a maximum usage of 20% municipal solid waste incinerator bottom ash as a replacement for soil.