Abstract: Concrete specimens with different aeolian sand content (mass substitution rate 0%, 25%, 50%, 75%, 100%) were prepared to conduct experimental research on the effect of aeolian sand content on chloride ion diffusion in concrete under cyclic freezing and thawing of chloride salt. The free chloride ion concentration and total chloride ion concentration in concrete with different aeolian sand contents under salt freezing environment were determined by chemical analysis method, and the relative chloride ion binding coefficient and chloride ion diffusion coefficient of aeolian sand concrete were calculated. Results revealed that the free chloride ion concentration declined at first but then increased with the augment of aeolian sand content, while gradually increased with the proceeding of cyclic freezing and thawing. The binding performance of aeolian sand concrete showed good Langumir nonlinear adsorption and had no direct relationship with freeze-thaw cycles. When the content of aeolian sand was 25%, the relative chloride ion binding coefficient was the smallest. The chloride ion diffusion coefficient hit the lowest value under the same freeze-thaw cycles. Cyclic freezing and thawing had little effect on the diffusion rate of chloride ion in concrete with large content of aeolian sand. The diffusion coefficient of chloride ion of the test group with 100% aeolian sand content decreased with the proceeding of freeze-thaw cycles, displaying good resistance to chloride ion erosion. Proper amount of aeolian sand could better resist chloride ion invasion, and a large amount of aeolian sand could boost the frost resistance of concrete under chloride salt erosion.

Key words: aeolian sand concrete, salt freezing, chloride ion, diffusion coefficient, cyclic freezing and thawing