Cross-scale study on the interaction behaviour of municipal solid waste incineration fly ash-asphalt mortar: a macro-micro approach
Xiaolong Sun, Hualong Xu, Xiao Qin, Yunchu Zhu, Jiao Jin
Abstract
To improve the safety and sustainability of municipal solid waste incineration (MSWI) fly ash in asphalt pavements, this study investigates the interaction mechanisms between MSWI fly ash (as a mineral powder substitute) and asphalt through multi-scale approaches. First, macroscopic rheological models were employed to quantitatively analyze the effects of temperature, frequency, and fly ash substitution level on the interaction between MSWI fly ash and asphalt. Next, microscopic methods were used to characterize the morphological properties and interaction mechanisms at the MSWI fly ash-asphalt mortar interface. Finally, molecular dynamics simulations were employed to compare the interaction dynamics of asphalt-MSWI fly ash and asphalt-mineral powder systems. Results show that increasing the substitution level of MSWI fly ash improves the asphalt-filler compatibility, particularly at elevated temperatures and low frequencies. The porous surface morphology of MSWI fly ash promotes asphalt adhesion through physical interactions. Superior interfacial adhesion was observed between MSWI fly ash and asphalt (254.97 kcal/mol), exceeding limestone mineral powder by 7%. The compositional analysis attributed this enhancement to the preferential accumulation of aromatic and resin components at MSWI fly ash interfaces. This study provides a theoretical basis for enhancing the immobilization of heavy metals in MSWI fly ash by asphalt binders.