Abstract: In order to study the deterioration mechanism of concrete under the freeze-thaw cycle of sodium sulfate,the loss rate of mass,compressive strength and relative dynamic elastic modulus of iron tailings concrete were tested,and a freezethaw damage model based on Weibull distribution was established. The results show that when the replacement rate of iron tailings is 60%,the quality loss of iron tailings concrete is 1. 7% after 150 freeze-thaw times. The compressive strength loss rate of iron tailings concrete increases with the increase of freezing and thawing times. After 60 freeze-thaw cycles,the compressive strength loss rate of IC15 iron tailings concrete and IC45 iron tailings concrete is significantly lower than that of ordinary concrete. The relative dynamic elastic modulus loss of IC30 group iron tailings concrete is the smallest,while the relative dynamic elastic modulus loss of IC60 group iron tailings concrete is the largest. When the freeze-thaw cycle is 0~ 30 times,the relative dynamic elastic modulus decreases slowly and the loss is small. When the replacement rate of iron tailings is 30%,the relative dynamic elastic modulus loses the least,and the freeze resistance and sulfate resistance are the best. The freeze-thaw damage model of iron tailings concrete under the combined action of freeze-thaw cycle and sulfate erosion accords with Weibull distribution,and the correlation coefficient R2 is greater than 0. 96.

Key words: iron tailings,sodium sulphate,freeze-thaw cycle,quality loss rate,loss rate of compressive strength,damage model