The effect of freeze-thaw cycles on flexural behaviour of FRP-reinforced ECC beams

This paper presents experimental and theoretical investigations on the flexural utilised of FRP (fibre-reinforced polymer) rebar-reinforced ECC (engineered cementitious composite) beams subjected to freeze-thaw cycles. Eight FRP-reinforced specimens after subjected to 0, 50, 100 and 150 cycles of freeze-thaw were tested to failure under flexural loading. Experimental results show that the moment capacity decreases with the increase of freeze-thaw cycles regardless of the material used, but the decreasing rate of the reinforced ECC specimen is lower than that of the conventional reinforced concrete specimen. The bearing capacity, deflection and crack width of the reinforced ECC specimens under quasi-permanent combination of moments are 1.13 similar to 1.21, 0.66 similar to 0.90 and 0.71 times of those of the conventional reinforced concrete specimens, respectively. Due to the excellent tensile and durability performance of ECC materials, bearing capacity, stiffness and crack resistance of FRP-reinforced ECC beams are enhanced compared with their conventional counterparts, particularly with more freeze-thaw cycles. Based on the formulae from ACI 440 and GB 50608, taking into account of the contribution of ECC material and balanced reinforcement ratio, the simplified formulae are developed to estimate the moment capacity and stiffness of the FRP-reinforced ECC beams. The results predicted on the moment capacity and deflection are in good agreement with the corresponding experimental measurements.