Compressive constitutive model of polyvinyl alcohol fiber/cement composite material in frozen state

In order to study the compressive service of polyvinyl alcohol fiber/cement composites under freezing condition after freeze-thaw cycle, the compressive test of polyvinyl alcohol fiber/cement composites under freezing condition was designed. Firstly, the samples were subjected to 0-300 freeze-thaw cycles, and then the samples were subjected to compressive test at −18℃ under continuous low temperature. The relationship between compressive stress and strain and its influence mechanism were analyzed. On this basis, combined with the principle of equivalent stress and statistical damage theory, the compressive constitutive model of polyvinyl alcohol fiber reinforced cement composites in frozen state was established, and the evolution characteristics of damage variable with the number of freeze-thaw cycles were discussed. The results show that: with the increase of freeze-thaw cycles, the peak compressive strength of polyvinyl alcohol fiber/cement composite decreases, the peak strain increases, and the brittleness is obvious at ultimate destruction. The elastic modulus of the sample under high freeze-thaw cycles is mainly provided by the pore ice in the sample. The established model can predict the compressive stress-strain relationship of PVA fiber reinforced cement composites under freeze-thaw cycles. The freeze-thaw damage variate and total damage variate have significant correlation with freeze-thaw times.