干湿-碳化耦合作用对全珊瑚海水混凝土耐久性的影响

Effect of carbonation-drying-wetting on durability of coral aggregate seawater concrete

通过对不同强度等级的全珊瑚海水混凝土(CASC)进行海水干湿循环试验和海水干湿碳化耦合循环试验,以表面状态、质量损失率、动弹性模量、超声波波速、立方体抗压强度为评价指标,研究干湿循环、碳化和干湿碳化耦合作用对CASC耐久性的影响.结果表明:干湿循环、干湿碳化耦合作用下,CASC的质量损失率均随着侵蚀时间的延长而逐渐增加,先期比较平缓,增长幅度不大,经过10次循环后,其质量损失率的增长幅度明显增大;而CASC的动弹性模量和超声波波速均随着循环次数的增加逐渐降低,经过6次循环后,其速率趋于平缓,表面有微损伤;与初始28 d立方体抗压强度相比,CASC的立方体抗压强度下降幅度为8.8%~11.0%.干湿循环和碳化作用对CASC的海水侵蚀均有加速作用,干湿循环促进盐析现象的产生,加快混凝土的破坏.因此,干湿碳化耦合作用加速CASC的破坏.

Based on the drying-wetting cycles experiment and the carbonation-drying-wetting cycles experiment for coral aggregate seawater concrete(CASC)with different strength grades,the effects of carbonation-drying-wetting on the durability of CASC are studied with the surface state,mass loss rate,relative dynamic elastic modulus,ultrasonic wave velocity and cube compressive strength as indices.Results show that the mass loss rate of CASC increases gradually with the increase in cycle times in the drying-wetting and carbonation-drying-wetting cycles.The mass loss rate increases relatively slowly at the initial stage but it increases remarkably after 10 cycles.The relative dynamic elastic modulus and ultrasonic wave velocity decrease gradually with the increase in cycle times.After 6 cycles,the decrease rate of the relative dynamic elastic modulus and ultrasonic wave velocity of CASC tends to be flat and the surface is slightly damaged.Compared with the initial 28 d cube compressive strength,the cube compressive strength of CASC decreases by 8.8%to 11.0%.Drying-wetting cycles and carbonation can accelerate seawater erosion on CASC,and drying-wetting cycles result in salting-out and accelerate the destruction of concrete.Therefore,the carbonation-drying-wetting accelerates the destruction of CASC.