Feasibility study of using clay bricks made from municipal solid waste incinerator (MSWI) fly ash

Abstract

This study deals with the effect of MSWI (municipal solid waste incinerator) fly ash on fired clay bricks. Initially, the MSWI fly ash was characterized by its chemical composition and morphology. Different ratios of the MSWI fly ash (0, 2.5, 5.0 and 7.5 % by mass) were added to the clay brick. Clay brick samples were heated on 1000 °C temperatures for 1 h. The clay brick properties of the resultant material then determined, including shrinkage (after drying, after firing), density, water absorption, effective porosity and total open porosity and compressive strength. Toxicity Characteristic Leaching Procedure tests were also conducted. The results indicate that the heavy metal, chloride and sulphate concentrations in the leachates met the current regulatory thresholds (Waste Directive 2003/33/EC). Increasing the amount of MSWI fly ash resulted in an increase in the water absorption and a decrease in the compressive strength of the MSWI fly ash clay bricks. The addition of MSWI fly ash to the mixture reduced the degree of firing shrinkage. The effects of MSWI fly ash addition on the durability (frost resistance) of the clay bricks were investigated. This indicates that MSWI fly ash is indeed suitable for the partial replacement of the clay in the bricks.