Preparation and Performance Evaluation of Gel-Coated Salt Storage Additives in Antifreeze Asphalt Pavement

Antifreeze asphalt pavements incorporating salt storage additives offer a promising solution to road ice and snow management. However, the adverse effects of these additives on asphalt mixtures have hindered the development of this technology. To address this issue, this study investigated the use of silica gel as a slow-release layer for salt storage additives, leading to the development of a novel gel-coated salt storage additive (GSSA). To fully assess the applicability of GSSA in asphalt pavement, it was incorporated into both asphalt mortar and mixtures by replacing mineral powder with an equal volume, followed by a series of microscopic and macroscopic experimental evaluations. The results showed that the particle morphology and gradation of GSSA are similar to those of conventional mineral fillers, with the silica gel component exhibiting a dense, porous network structure. Sodium chloride (NaCl) was uniformly distributed within this structure, providing effective slow-release properties. The appropriate addition of GSSA enhances the water stability and thermal crack resistance of asphalt mixtures, although it slightly reduces high-temperature stability. The observed changes in high- and low-temperature performance of the asphalt mortar correspond to those of the asphalt mixture. Additionally, GSSA lowered the freezing point and delayed surface icing. However, excessive GSSA content reduced the stability of asphalt mortar and compromised the durability of the antifreeze asphalt mixture. Replacing up to 50% of the mineral powder with GSSA provided optimal overall performance.