Potential utilization of municipal solid waste incineration ashes as sand replacement for developing sustainable cementitious binder

Abstract

This paper investigates the ability of recycling the municipality solid waste incineration (MSWI) ashes as sand replacement in cementitious binder production. Two types of MSWI ashes were considered in this study including fly ash and bottom ash. The ashes were characterized, and then incorporated into the mixes as sand replacement with different ratios: 0%, 10%, 20%, and 30%. Comprehensive experimental work was conducted to investigate the mechanical strengths, workability, density, water absorption, thermal conductivity, thermal stability, chemical composition, and heavy metals content of the prepared binders. The results reflected the ability of producing sustainable cementitious binder with low dosage of MSWI ashes (up to 10%) as sand replacement with good mechanical properties, and accepted workability, water absorption, and thermal stability. Partially substitution of sand with MSWI ashes enhanced the early (3-day) compressive strength of cement mortar. Optimum enhancements of 16% and 45% were achieved at 10% and 20% replacement ratios in the case of mortar with MSWIFA and MSWIBA, respectively. Using the MSWI ashes as sand replacement resulted in better compressive strength of the mortar compared to the common approach of using it as cement replacement. However, the chemical composition analysis showed the presence of heavy metals in the hydration products of the binder. The mobility and leaching of these metals should be taken into consideration before any possible application of these materials.