Reuse of stabilized municipal solid waste incinerator fly ash in asphalt mixtures

A laboratory investigation evaluates the potential of using stabilized fly ash from municipal solid waste incinerators (MSWIs) as a filler in asphalt mixtures. Nine asphalt mixtures composed of the same aggregate gradation and three different asphalt binders and three different fillers (limestone and two stabilized fly ashes) are prepared and tested. A chemical and mineralogical investigation characterizes the fillers before and after mixing with asphalt binders. The behavior of the mastics at low temperatures is estimated by a bending beam rheometer (BBR) test. The mixtures' cracking behaviors at intermediate temperature are evaluated using the HMA fracture mechanics model. Results show that stabilized fly ash obtained from MSWIs can be reused as a filler in asphalt mixtures if the fly ash is subjected to a water leaching procedure to remove soluble salts. Mechanical properties of mixtures containing washed fly ash as a filler are in very good agreement with results obtained from the same mixtures containing traditional filler.