超低温冻融循环下钢筋与混凝土的黏结性能

借助低温冰箱和超低温环境箱降温的方式,对7组21个试件分别进行了不同循环次数、不同温度变化的超低温冻融循环.通过对冻融循环后试件的中心拔出试验,得到了钢筋与混凝土的荷载-滑移曲线.结果表明,在循环次数较少的情况下,低温对钢筋与混凝土的荷载-滑移曲线形状影响不大,但对两者的黏结强度有明显的降低作用;在冻融循环中,20~-75,℃温度段对钢筋与混凝土的黏结强度降低作用明显,相比之下,-75~-120,℃温度段对钢筋与混凝土黏结强度的后续降低作用不明显;随着循环次数的增多,每次循环对于钢筋与混凝土黏结强度的降低作用逐渐减弱.

Bonding Properties Between Reinforcement and Concrete After Freeze-Thaw Cycles at Extra-Low Temperatures

With the cooling system of low-temperature refrigerator and extra-low temperature environment box,freeze-thaw cycles for 7 groups of 21 specimens with different cycle times and at different low or extra-low temperatures were carried out. Through the pull-out test of specimens after freeze-thaw cycles,the load-slip curves between reinforcement and concrete were recorded. The results show that,with fewer cycle times,the tendency of the loadslip curves almost has no changes,but the bonding strength between reinforcement and concrete is reduced significantly;the bonding strength between reinforcement and concrete decreases obviously at 20—-75,℃,while the bonding strength has no obvious follow-up reduction at-75—-120,℃ in freeze-thaw cycles;the reduction of the bonding strength reduces gradually with each cycle.