Effective and sustainable use of municipal solid waste incineration bottom ash in concrete regarding strength and durability

Abstract

An effective approach to reduce the enormous volume of non-hazardous non-recyclable waste (namely municipal solid waste, or MSW) is incineration. The incineration can be a viable solution given that landfilling of MSW is both expensive and polluting. The obtained bottom ash is a material with great potential to be used in cementitious products as partial cement replacement. This has the double advantage of reducing landfill and reducing the cement content in cementitious products (since cement is largely responsible for their carbon footprint). So far, most studies have been done at laboratory scale and mainly in pastes and mortars. In this research, the valorisation of ground MSW incineration (MSWI) bottom ash as substitute for Portland cement in concrete is analysed. This work presents the insights obtained regarding the use of MSWI ashes as binder in concrete, and their constitutive behaviour in terms of fresh and hardened properties, as well as durability properties. As a result, a well-performing concrete mix containing processed MSWI ashes as 20% of the binder has been designed. Quantification of the overall sustainability, in relation to the expected environmental impact, was also performed considering a preliminary life cycle assessment. The valorisation of the studied ashes by their use in concrete is a promising path to increase the sustainability of concrete and to upscale a waste product.