Fracture behavior of dredged sand concrete under freeze–thaw cycles

Abstract

In order to investigate the frost resistance and fracture behaviors of dredged sand concrete, three kinds of concrete with different dredged sand contents (0%, 25%, and 50%) by weight were designed and subjected to different freeze–thaw cycles (0, 25, 50, 75 and 100). Three-point bending fracture tests were performed on the frozen concrete specimens combined with acoustic emission (AE) technique. The results show that the mass loss of dredged sand concrete increases, the relative dynamic elastic modulus and compressive strength decreases with the increase of the freeze–thaw cycles. With the increase of dredged sand content, the pore structure is improved, so the fracture behavior and frost resistance of concrete are improved. With the increase of the dredged sand content of concrete, the fractal dimension of the fracture surface decreases. With the increase of the freeze–thaw cycles, the fractal dimension of the fracture surface increases, and the fracture surface is rougher. The higher the freeze–thaw cycles, the lower the peak load, fracture toughness and fracture energy of dredged sand concrete. The higher the content of dredged sand, the greater the fracture energy of dredged sand concrete. The accumulate AE counts, AE energy and AE b-value can reflect three-stage failure process of dredged sand concrete. The damage model of dredged sand concrete established based on the AE events obeys Weibull distribution, which can reflect the effect of freeze–thaw cycles on damage.