Abstract
Municipal solid waste and cement manufacture are two sources of environmental justice issues in urban and suburban areas. Waste utilization is an attractive alternative to disposal for eliminating environmental injustice, reducing potential hazards, and improving urban sustainability. The re-use and recycling of municipal solid waste incineration (MSWI) ash in the construction industry has drawn significant attention. Incorporating MSWI ash in cement and concrete production is a potential path that mitigates the environmental justice issues in waste management and the construction industry. This paper presents a critical overview of the pretreatment methods that optimize MSWI ash utilization in cement/concrete and the influences of MSWI ash on the performance of cement/concrete. This review aims to elucidate the potential advantages and limitations associated with the use of MSWI ash for producing cement clinker, alternative binder (e.g., alkali-activated material), cement substitutes, and aggregates. A brief overview of the generation and characteristics of MSWI ash is reported, accompanied by identifying opportunities for the use of MSWI ash-incorporated products in industrial-scale applications and recognizing associated environmental justice implications.
Highlights
Urbanization has resulted in environmental issues and unfair distribution of environmental benefits and burdens to different types of populations [1]
Higher fractions of raw municipal solid waste incineration (MSWI) bottom ash (BA) may be added into PC feedstock due to its lower content of chlorides and alkalis compared to raw MSWI fly ash (FA)
Among different washing conditions (water-to-solid ratio and solutions (water, (NH4)3PO4, and HCl)), only mortar containing 10% FA water-washed at a water-to-solid ratio of 10 exhibited a 5% higher 28d compressive strength compared to an Ordinary Portland cement (OPC) reference
Summary
Urbanization has resulted in environmental issues (e.g., pollutions and climate change) and unfair distribution of environmental benefits and burdens to different types of populations ( known as environmental inequity/injustice) [1]. The local raw materials extraction for cement and concrete production has significant environmental and health impacts on the low-income or POC populations [25,26]. Existing articles are mainly case studies of the mechanical performance and environmental impacts of MSWI ash-incorporated cement-based materials [35,36]. This paper aims to link existing work and trends in MSWI ash-incorporated cement and concrete and explore future paths to mitigate environmental injustice at scale. This paper serves as a tutorial review for scientists and engineers new into the field of MSWI ash-incorporated cement/concrete, technical support for life-cycle assessment modelers and environmentalists, and a guide for decision-makers to mitigate environmental justice issues. The compositions of MSWI ash depend on many factors (e.g., MSW sources, metals separation technologies, and incineration facilities) [31].
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