Optimization of slow-release salt storage snowmelt aggregate preparation process and its slow-release performance based on response surface methodology-orthogonal test

Salt storage asphalt pavement can effectively alleviate the problem of pavement snow and ice in winter, and ensure the driving safety and transportation capacity. Salt storage type snow melting and ice suppression materials are the key to the function of salt storage asphalt pavement. The purpose of this paper is to develop a snow-melting and ice suppression aggregate with outstanding sustained release performance by coupling the orthogonal test and response surface method. Three process variables, such as adsorption time, concentration of snow-melting salt solution and mass ratio of porous aggregate to snow melting salt, were optimized by orthogonal test and response surface method. Then, the preparation process of salt storage aggregate was determined by adsorption performance test. Finally, the physical and mechanical properties, slow release performance and ice melting performance of the slow-release salt-storage snowmelt aggregate were tested. The results showed that the optimum preparation process of salt-storing aggregate was the adsorption time of 12 h, concentration of snow-melting agent solution of 30 %, and mass ratio of snow-melting salt to salt-storing carrier of 0.5:1. The optimum mass ratio of salt-storing aggregate to wrapping material (phenolic resin) was 1:2.5. The salt release amount of the slow-release salt-storing snowmelt aggregate at 180 min was about 43.75 % lower than that of the unwrapped salt-storing aggregate. At the same time, 5 g of slow-release salt-storing snow-melting aggregate had a melting ice amount of 0.9 g at a temperature of −5°C. In addition, the slow-release salt-storing snow-melting aggregates wrapped with different proportions of asphalt could release salt, and its conductivity was at least 1200 μs/cm in the stable stage.