氯盐冻融耦合作用下再生混凝土损伤劣化规律

Deterioration Law of Recycled Concrete under the Coupling of Chloride and Freeze-Thaw

为了研究严寒盐渍环境中再生混凝土的损伤劣化规律,制备了再生粗骨料质量替代率为0%、50%、100%的再生混凝土进行氯盐冻融耦合作用下的试验研究,从外观形貌、质量损失率、相对动弹性模量和抗压强度等方面探讨混凝土损伤劣化规律。结果表明,氯盐冻融对再生骨料混凝土的破坏随再生骨料替代率的增加而增大。与冻融循环0次相比,冻融循环200次时100%替代率再生混凝土的质量损失率、相对动弹性模量、相对抗压强度分别下降为6.8%、54.2%、50.5%。建立了以抗压强度损失率为损伤变量的线性演化模型,模型可以较好地表征氯盐冻融作用下再生混凝土的损伤劣化规律,为严寒盐渍地区再生混凝土使用提供理论依据。

In order to study the damage and deterioration law of recycled concrete in severe cold and saline environment,the recycled coarse aggregate mass replacement rate of 0%,50%,and 100%of recycled concrete were prepared to carry out the experimental study under the coupling of chloride and freeze-thaw.And its damage and deterioration law was discussed from the aspects of appearance,mass loss rate,relative dynamic elastic modulus and compressive strength.The results show that the damage to recycled aggregate concrete caused by chloride and freeze-thaw increases with the increase in the replacement rate of recycled aggregate.Compared with 200 freeze-thaw cycles and 0 freeze-thaw cycles,the mass loss rate,relative dynamic elastic modulus and relative compressive strength of the recycled concrete with 100%replacement rate decrease by 6.8%,54.2%and 50.5%,respectively.The mass loss rate used to evaluate the durability of recycled concrete against salt and freezing has certain limitations.The loss rate of compressive strength is more suitable to characterize the degree of durability damage of recycled concrete than the relative dynamic modulus.A linear evolution model based on the loss of compressive strength as the damage variable is established.The model characterizes well the damage and deterioration of recycled concrete under the action of chloride and freeze-thaw,and provides a theoretical basis for the use of recycled concrete in severe cold and saline areas.