Interfacial adhesive property in “asphalt mixture-PMA copolymer-steel plate” system: Experimental and molecular dynamics simulation

Abstract In this article, poly(methyl methacrylate/n-butyl acrylate) copolymer (PMA) is being considered for utilizing as a waterproof adhesive layer (WAL) on the steel bridge deck. Toughness modification of methacrylate-based adhesive (MMA) was carried out by adding n-butyl acrylate (nBA) using the emulsion polymerization method to overcome its brittleness. The “Asphalt mixture-MMA-Steel plate” interfacial morphology was analyzed by SEM. The MMA and asphalt mortar play the main role at the WAL-asphalt mixture bonding interface was proved by microscopic characteristic analyses. Besides, molecular dynamics (MD) simulation has been used for the construction of atomistic models of PMA with different molar ratios. The adjacent interface adhesion properties of “Asphalt- PMA-Steel plate” connection has been investigated by calculating the interaction energy. The simulated results show that 50/50 PMA has good adhesion bonding between copolymer to steel plate/ asphalt surface. The van der Waals (vdW) force played an essential role in interfacial adhesive properties. The bonding between the steel plate and the PMA copolymer layer within the three-layer structure is comparatively more stable than that of the interface between the PMA layer and the asphalt layer. Differential scanning calorimetry (DSC) test results confirmed the toughness effect of nBA that increases the slippage of PMMA chains past each other and resulted in a decrease of Tg. The pull-off and direct shear test evidenced that the PMA rather than MMA has better compatibility with epoxy asphalt concrete (EA) in both room or high-temperature zones. This work aims to study the adhesion properties between steel plate/asphalt and PMA at multi-scale and provide guidance and reference for researchers to design and develop a new waterproof layer.