Effect of carbonation freeze-thaw on chloride ion transport in aeolian sand concrete
In order to study the effect of carbonation freeze-thaw cycle on chloride ion transmission of aeolian sand concrete,the ex-perimental study of freeze-thaw cycle(50,100,150,200)of all aeolian sand concrete after carbonation(0,14,28 d)was carried out.The chloride ion in concrete at different depths was detected by chemical titration,and then the relationship between chloride ion content,distribution,chloride ion diffusion coefficient,carbonation depth and time dependence was analyzed.The internal structure of concrete was observed by scanning electron microscope.The results showed that the carbonation products produced by carbonation made the concrete more dense and could effectively resist the corrosion of chloride ions,and the longer the carbonation time was,the more obvious the effect of resisting the corrosion of chloride ions was.The freeze-thaw cycle increased the generation of concrete cracks and provided a channel for the internal transmission of chloride ions;With the increase of the number of freeze-thaw cycles,the chloride ion erosion was also more serious.When the freeze-thaw cycle was 100 times,C0 group was invaded by chloride ion at chloride ion invasion depth 30 mm,and when the freeze-thaw cycle was 150 times,chloride ion invasion depth 30 mm of all con-crete was eroded by chloride ions.Under the condition of 200 freeze-thaw cycles,the time-dependent coefficient of group C1 in-creased by 42.22%compared with group C0,group C2 increased by 57.78%compared with group C0,and increased by 10.94%compared with group C1.The mass fraction of chloride ions in aeolian sand concrete increased with the increase of freeze-thaw cy-cles and decreased with the increase of carbonation depth.