Evaluating the Use of Waste-to-Energy Bottom Ash as Road Construction Materials

Abstract

Current management practice, existing regulations, and environmental consequences of municipal solid waste incineration (MSWI) ash utilization were comprehensively reviewed worldwide and nationwide in the U.S. Efforts were made to physically and chemically characterize different types of MSWI ash and also to evaluate their influence on engineering properties of cement paste and concrete when part of Portland cement (PC) and fine aggregate are replaced with ground and sieved MSWI ash. Fundamental properties of MSWI bottom ash and fly ash were studied by conducting physical, microstructural, and chemical tests. Cement paste and concrete cylinders were cast with various amounts of ash additions and their strength and durability were investigated as the replacement ratio of ash increases. The MSWI bottom ash was also used to replace fine aggregate in hot-mix asphalt (HMA). Varying proportions of bottom ash and fine aggregate were tried in an effort to determine the optimum ratio of bottom ash to fine aggregate, as determined by performance tests such as the Marshall stability test and the moisture susceptibility test. For the optimum replacement ratio of bottom ash, the optimum binder content required was evaluated.