An eco-friendly crack sealant approach for asphalt pavement by using laboratory tests and molecular dynamic simulation

Abstract

Waste engine oil (WEO) is detrimental to the environment and challenging to recycle on a large scale. Fortunately, the utilization of WEO as an additive in asphalt pavement crack sealant offers both economic benefits and engineering feasibility. In this study, an eco-friendly crack sealant was prepared using WEO and crumb rubber (CR) modified asphalt (WCRA). The viscoelasticity, storage stability, adhesion, and water resistance properties of the sealant were tested to evaluate its suitability for crack repair. In addition, molecular dynamic (MD) simulation was employed to elucidate the interface adhesion mechanism of the sealant-crack wall interface. The test results demonstrated that the viscosity of the sealant is primarily proportional to the content of CR and inversely proportional to WEO. Furthermore, the storage stability is satisfactory after the addition of moderate WEO. The medium and high temperature flexibility of the sealant is between base asphalt and SBS-modified asphalt. Based on the laboratory tests, 35% (by weight of base asphalt) microwave-treated CR and 25% (by weight of CR) WEO are the optimal proportions for preparing the sealant. MD simulation demonstrated that CR inhibits the diffusion of asphalt components and aggregates asphaltenes in close proximity to the crack wall surface. WEO not only stimulates molecular activity but also maintains the equilibrium of the asphalt colloid system, which is conducive to the penetration and water resistance of the sealant. The study will provide a reference for the utilization of waste materials and the cost-effective repair of asphalt pavements.