Study on the strength size effect of wastewater concrete under freeze-thaw cycles

In this study, the size effect on the strength of wastewater concrete under freeze-thaw cycles was evaluated. Cube specimens of wastewater concrete with side lengths of 40 mm, 100 mm, 150 mm, and 200 mm were prepared, and the resulting compressive and splitting tensile strengths after exposure to 0, 10, 20, 30, 40, and 50 freeze-thaw cycles were determined. The results show that the size effect is increasingly affected by freeze-thaw cycles with the increase in the number of cycles, while the corresponding specimen brittleness is gradually reduced, and the plasticity is enhanced. The modified Bazant size effect model considering the effect of freeze-thaw cycles on size effect was established. The modified size effect curve considering the freeze-thaw damage can be used to predict the initial strength of specimens after freeze-thaw cycles. The predicted data points were mainly distributed on the size effect curve and could directly reflect the size effect phenomenon of wastewater concrete without freeze-thaw cycles.