Utilization of municipal solid waste incinerator fly ash as a partial cement replacement on concrete

Abstract

The physical and chemical properties of sifted and washed samples of municipal solid waste incinerator fly ash (MSWIFA) collected from mass-burn incinerator in Phuket, Thailand were determined. Tests included specific gravity, particle size distribution, specific surface area, moisture content, loss on ignition, absorption capacity, morphology, bulk chemical compositions, and mineralogical compositions. Results showed that properties of MSWIFA did not meet most of the requirements of ASTM C618. MSWIFA was used to directly replace cement by up to 25% for making MSWIFA concrete. Parameters under investigation included properties of fresh concrete, development of compressive strength from 3 to 90 days, and water-soluble chloride content. The results showed that compressive strengths of all MSWIFA concrete specimens were lower than those of control concrete. It was found that chloride, a soluble fraction of MSWIFA, accelerated setting time of concrete andimproved compressive strength compared to that of washed MSWIFA concrete. Fortunately, water-soluble chloride contents of all samples were within the limits set by the Engineering Institute of Thailand to prevent corrosion of reinforced steel. Leachate extraction procedure described in the Notification of Ministry of Industry No.6 (1997) was used to evaluate environmental safety of MSWIFA and concrete products. Results showed that concentrations of all regulated metals were within the limits. However, it should be noted that concentrations of barium, lead, and chloride in wastewater from washing process were higher than effluent standards.