Utilization of Municipal Solid Waste Incineration Fly Ash in Ecological Concrete and Pavement Bricks: Mechanical Properties and Environmental Impact

This study examines the feasibility of incorporating municipal solid waste incineration fly ash (MSWIFA) into the production of ecological concrete (EC) and ecological concrete pavement bricks. As a byproduct of urban waste incineration, MSWIFA contains hazardous pollutants such as dioxins and heavy metals, prompting the necessity for effective disposal methods to mitigate environmental impacts. The research investigates how varying levels of MSWIFA affect the properties of EC and evaluates the microstructural, economic, and ecological advantages of utilizing MSWIFA in EC production. Furthermore, the study evaluates the environmental risks associated with MSWIFA and the resultant concrete bricks. Key findings indicate that a 10 % substitution rate of MSWIFA enhances EC's flexural strength, compressive strength, ultrasonic pulse velocity, and elastic modulus, attributed to the elevated calcium and chloride ion concentrations that boost cement hydration and mechanical properties. Conversely, higher MSWIFA substitution results in reduced flexural and compressive strength and a decline in porosity due to increased chloride ion migration. Energy consumption, carbon emissions, and production costs consistently decrease with elevated MSWIFA substitution rates. Ecological concrete pavement bricks with a 20 % MSWIFA substitution ratio show enhanced flexural and compressive strengths compared to standard concrete bricks, along with superior performance post-freeze-thaw cycles. The environmental risk posed by MSWIFA is deemed low, and the heavy metal risk index in the ecological bricks is well below the low-risk threshold, suggesting negligible environmental risks. Overall, the findings advocate for the resource-efficient application of MSWIFA in manufacturing sustainable concrete materials with manageable environmental risk.