Capillary water absorption performance and damage constitutive model of recycled concrete under freeze–thaw action

Abstract

In order to study the capillary water absorption and damage characteristics of recycled aggregate concrete (RAC) after freeze–thaw cycles, the capillary water absorption and the stress–strain curve under uniaxial compression of recycled coarse aggregate replacement rates of 0%, 30% and 50% RAC were tested. The effects of recycled coarse aggregate replacement rate and freeze–thaw cycles on the mass loss, compressive strength, relative dynamic elastic modulus and capillary water absorption of recycled concrete were analyzed. According to the basic theory of damage mechanics, the damage constitutive model of recycled concrete was established based on the double factors of replacement rate and freeze–thaw cycles. The results show that with the increase of freeze–thaw cycles, the mass, compressive strength and relative dynamic elastic modulus of RAC with different substitution rates decrease, and the water absorption rate increases first and then tends to be stable. After freezing and thawing, the peak stress of each substitution rate RAC decreased in varying degrees, and the peak strain increased slightly. The test results are compared with the calculation results of the constitutive model, and the two are in good agreement, which has certain reference significance for the promotion and application of recycled concrete in cold regions.