Abstract:In order to ameliorate the durability of recycled concrete at cold regions, the effects of the replacement rate of recycled concrete and sequence of carbon fiber reinforced polymer(CFRP) reinforcement on the loading capacity of recycled concrete columns under freeze thaw cycled environment were systematically investigated. The experimental result shows that the ultimate bearing capacity of recycled concrete without CFRP reinforcement is significantly reduced by freeze thaw cycle. However, surprisingly, the postmortem CFRP reinforcement with 0%, 50%and 100% recycled concrete can improve the ultimate bearing capacity of freeze thaw cycled samples to levels of about 1514, 1502 and 2088 times higher than that of the corresponding samples not suffered freeze thaw cycle, respectively. These indicate that CFRP reinforcement is an effective way in recuperating the load bearing capacity and optimizing the damage resistance of recycled concrete under freeze thaw cycled environment. In addition, the pre reinforced columns after freeze thaw cycle still exhibit higher ultimate bearing capacity than that of the original samples without reinforcement. Basing on both the axial compression constitutive model and the relationship between radial force and axial strain, a new load bearing formula is deduced for recycled concrete column under the influence of both CFRP reinforcement and freeze thaw cycle.