Durability improvement of poroelastic road surface with treated rubber: Molecular dynamics simulation and experimental observations

Poroelastic road surface (PERS) is usually composed of rubber particles, aggregates, and polyurethane. However, the poor bonding strength between rubber granules and polyurethane affects PERS’ durability. This study aimed to improve the durability of PERS with treated rubber using molecular simulation and experimental tests. The cohesive energy density (CED), interaction energy (IE) and shear bonding capacities between two kinds of rubber granules and one-component polyurethane were simulated using molecular dynamics (MD). The hydrophilicity test and Fourier transform infrared (FTIR) spectroscopy test were utilized to demonstrate the formation of oxygen-containing groups on rubber surfaces. The indirect tension (IDT) test and Cantabro test were employed to evaluate the durability of PERS mixtures with treated rubber. The MD simulation results showed that the oxygen-containing groups, including the hydroxyl group (-OH) and the carbonyl group (CO), could improve surface polarity of natural rubber (NR) and styrene-butadiene rubber (SBR) and thereby enhance rubber-polyurethane bonding performance. In particular, hydroxyl groups improved the bonding energy of NR-polyurethane by 59% while the carbonyl groups enhanced the bonding performance of SBR-polyurethane by 20%. The hydrophilicity of the treated rubber granules was effectively improved since new carbonyl groups were introduced on rubber surface. The treatment of rubber with NaOH solution improved the durability of PERS specimens by 8.4% in terms of tensile strength ratio (TSR) and 64.7% in terms of Cantabro abrasion loss. These findings prove the feasibility of designing durable PERS with good functional performance.