干湿-冻融交替作用下混凝土受硫酸盐侵蚀研究

Sulfate attack on concrete under alternate freeze-thaw and dry-wet cycling

冻融循环、干湿循环及硫酸盐侵蚀是影响混凝土耐久性能的重要因素。分别采用单一干湿循环、单一冻融循环、干湿-冻融交替循环3种方法,研究混凝土在水和不同浓度硫酸盐溶液(1%、5%、10%)中的耐久性能指标,包括质量损失率和相对动弹性模量。研究发现,干湿循环和冻融循环作用效应并非简单叠加,而是超叠加效应,两者相互促进,共同作用,干湿-冻融交替作用下混凝土劣化最快。硫酸盐浓度对混凝土耐久性能影响显著,硫酸盐浓度越大,干湿-冻融后混凝土相对动弹性模量越低,混凝土损伤越严重。

Freeze-thaw cycles,dry-wet cycles and sulfate attack are the important parameters impacting the durability of concrete.The experiment used three different methods,including dry-wet cycles,freeze-thaw cycles,freeze-thaw and dry-wet alternate cycles.Durability performance of concrete in water and different concentrations of sulfate solution（1%,5%,10%）were studied,including the mass loss ratio and residual dynamic elastic modulus.Results show that action effect of dry-wet cycles and freeze-thaw cycles is not simple superposition,but the super superposition effect.The two cycles promote each other,and concrete under freeze-thaw and dry-wet cycles deteriorate fastest.Sulfate concentration has a significant impact on concrete durability.The greater the sulfate concentration,the lower the residual dynamic elastic modulus of concrete,and the greater the degree of deterioration.