# Effect of an Organic Rectorite on the Properties of a Waste Engine Oil-Modified Asphalt
## 1 Introduction  
The utilization of solid waste materials in road materials and structures is an effective and environmentally responsible approach to achieving sustainable development in road engineering. One such waste material is waste engine oil (WEO), which is generated annually in large quantities, reaching approximately 40 million tons from motor vehicle services alone, according to reports [1]. In order to effectively recycle and utilize WEO while avoiding environmental pollution caused by incineration, dumping, and landfilling, there is growing interest in exploring its application in asphalt pavements [2; 3; 4; 5; 6; 7]. WEO contains a significant amount of aromatic solvents, paraffinic oils, and polyolefin oils, among other low-molecular-weight components [8]. The presence of aromatic components in WEO can increase the content of lightweight fractions in the asphalt matrix [9], thereby softening the asphalt [10; 11; 12]. Previous studies have primarily focused on using WEO as an asphalt rejuvenator, as it can compensate for the loss of lightweight components in aged asphalt and help restore its performance [2; 13; 14]. However, researchers have also turned their attention to utilizing WEO as an asphalt modifier or substitute, givenits similar functional groups and molecular structure to asphalt [8; 15]. This approach presents a promising avenue for addressing environmental concerns related to the disposal of waste engine oil while simultaneously seeking sustainable solutions in road construction and maintenance. Research findings indicate that WEO can enhance the asphalt's low-temperature crack resistance, self-healing property, and aging resistance, but it significantly affects the high-temperature rutting resistance of the asphalt [1; 8; 9; 16]. This significant reduction in high-temperature rutting resistance severely limits the practical application of WEO-modified asphalt in road engineering [16]. Moreover, higher WEO content can reduce the storage stability of the corresponding WEO-modified asphalt, impacting its construction and workability. Hence, finding a balance or improving the overall performance of WEO-modified asphalt is crucial for determining its potential for engineering applications. Layered silicates, known as naturally occurring nanoscale clays, have emerged as a valuable additive for enhancing the high-temperature rutting resistance and aging resistance of asphalt [17; 18; 19]. In particular, these silicates have shown promising results in improving the storage stability of polymer-modified asphalt. The unique structure of layered silicates allows them to disperse uniformly within the asphalt matrix, forming a stable network that enhances the overall performance of the asphalt mixture [20; 21]. Among the most commonly used layered silicates are montmorillonite (MMT) and its organically modified derivatives [22; 23; 24]. [PERSON] et al. [20] employed organically modified montmorillonite (OMMT) to enhance the storage stability, high-temperature stability, and aging resistance of SEBS-modified asphalt. The research findings showed that the addition of 3 wt% OMMT reduced the 48-h softening point difference of SEBS-modified asphalt from 8.5 \({}^{\circ}\)C to 1.1 \({}^{\circ}\)C, significantly improving the storage stability of SEBS-modified asphalt. This improvement was attributed to OMMT's ability to promote the uniform dispersion of SEBS in the asphalt matrix. Other relevant research has confirmed that OMMT can enhance the storage stability of polymer-modified asphalts, such as those modified with waste packaging polyethylene and polyurethane thermoplastic elastomers, compensating for the reduced high-temperature stability caused by the polymers, albeit at the cost of decreased low-temperature crack resistance [19; 25]. [PERSON] et al. [26] found that MMT can inhibit the evaporation of lightweight components in asphalt, thus reducing the impact of aging time on the self-healing performance of SBS-modified asphalt.