Multi-Objective Optimization of Performance Characteristics of Asphalt Containing Recycled Additives Using Response Surface Method

The use of rubber powder and carbon powder additives in pavement, despite its technical and environmental advantages, faces limitations that require optimization of their usage percentage. The aim of this research is to optimize the mechanical properties of asphalt in order to increase the lifespan and quality of the pavement and reduce maintenance costs based on laboratory results. The input variables include the percentage of carbon powder and rubber powder, and the output variables include the modulus of elasticity, moisture resistance, fracture energy, rutting depth, and asphalt cumulative strains. The mathematical process model for each asphalt mechanical characteristic was determined using response surface method (RSM) and its accuracy was checked by variance analysis. The results showed that the statistical analysis of RSM is highly accurate and the linear variables of CRM and ACP have a significant effect on the mechanical and functional behavior of asphalt. The optimal conditions for maximizing the mechanical characteristics of asphalt were proposed as ACP equal to 44.4% and CRM equal to 14.9%. The comparison of the optimized and minimum laboratory conditions showed that the use of the optimal combination of rubber powder and carbon powder, respectively 9%, 53% and 69% improvement in moisture resistance, fracture energy and modulus of elasticity, as well as 48% and 44% reduction in the depth of rutting. and creates plastic strain. In general, the results of this research show that the optimization of fracture energy, modulus of elasticity and moisture resistance, along with the reduction of rutting, can lead to an increase in the quality and lifespan of the pavement and a reduction in maintenance costs.