Salt frost resistance of concrete with crushed asphalt particles: Experiments and modelling

Asphalt coating is widely utilized for its excellent impermeability on marine structure surface. However, in high latitude regions, the coupling effect of freeze-thaw cycles and chemical aging rapidly diminished the protective effect, significantly increasing the risk of structural damage. Therefore, to maximize the impermeability and durability of asphalt, we homogeneously intermixed the crushed asphalt particles into the concrete instead of surface coating. A series of crushed asphalt particles concrete (CAPC) with different asphalt content were prepared and subjected to up to 30 salt freeze thaw cycles (SFTCs) in a 3.5 wt% NaCl solution. Experimental results revealed that addition of asphalt particles improved pore structure and impermeability, mitigating frost damage and chloride diffusion. Optimal performance is observed at 2 % asphalt content, showcasing a notable 22.0 % reduction in porosity, a substantial 47.3 % decrease in chloride concentration at 10 mm depth after 30 SFTCs, with only a 3 % slight reduction in strength. Moreover, a multi-phase chloride diffusion model was proposed, considering matrix/asphalt damage and time-varying porosity. The influence of aggregate shape and volume, data-processing methods, long-term prediction under different regions were discussed. Compared with asphalt coating and classical concrete, the proposed CAPC is recommended for use under marine environment, especially in cold marine regions.