Effect and mechanism of waste glass powder silane modification on water stability of asphalt mixture

The loss of adhesion is one of the primary mechanisms of water damage in asphalt mixes containing waste glass powders (WGPs), which is mainly attributed to the smooth surface of the glass may undermine the bitumen–aggregate adhesion and accelerate the stripping. In this study, the WGPs surface was roughened by different types and content of silane coupling agent (SCA), and the surface modification mechanism was illustrated based on the chemical reaction process. Then the adsorption capacity of WGPs on SCA was studied through UV–vis tests, and the effects of the SCA on the chemical composition of WGP and asphalt were investigated by FT-IR tests. At the same time, the adhesion performance between modified WGPs and asphalt was studied by the sessile drop test and column wicking test. Furthermore, the immersion Marshall tests were completed to study the water stability of the asphalt mixture after the replacement of filler with modified WGPs. Results show that the optimal modified time of WGPs is 75 min. During the modified process, a ≡Si-O-Si≡ skeleton structure is generated between the SCA and WGPs, and the amino group in SCA reacts with the carboxylic acid of the asphalt to form a new chemical bond. In addition, adding 10 % KH550 SCA to modify the WGPs will provide the most superior improvement for the adhesion work, stripping work and water stability.