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为研究冻融作用对混凝土力学性能的影响,采用快冻法将混凝土盐冻或水冻至不同损伤程度后,测其动弹性模量、抗折强度、抗压强度和劈裂抗拉强度.以动弹性模量为损伤变量,分析了冻融损伤与抗折、抗压强度之间的关系,采用回归分析的方法建立了抗折强度衰减方程.结果表明,混凝土抗压、抗折、劈裂抗拉强度以及动弹性模量均随冻融循环作用次数的增加而逐步降低;抗折、劈裂抗拉强度以及动弹性模量的衰减速率随冻融循环作用次数的增加而不断增大,但抗压强度的衰减速率则是先增大后减小;在冻融循环次数相同的情况下,含气量越高、水灰比越低,混凝土的强度损失越小,其力学性能损失的大小顺序依次为:抗折强度和劈裂抗拉强度、动弹性模量、抗压强度;冻融损伤与抗折强度的相关性较好,但与抗压强度的相关性较差,当冻融损伤小于40%时,混凝土的抗压强度一般不低于其初始强度的70%.
In order to study the influence of freeze-thaw action on the mechanical properties of concrete, the dynamic modulus of elasticity, flexural strength, compressive strength and splitting tensile strength were measured by the method of fast freezing after the concrete was frozen in salt or water to different degrees of damage. The dynamic elastic modulus as the damage variable, the relationship between the freeze-thaw damage and the flexural and compressive strength was analyzed, and the regression equation was used to establish the decay strength decay equation.The results showed that the compressive strength, flexural resistance, Cracking tensile strength and dynamic elastic modulus all decreased gradually with the increase of the number of freeze-thaw cycles. The decay rate, the splitting tensile strength and the decay rate of dynamic elastic modulus increased with the increase of the number of freeze-thaw cycles , But the decay rate of compressive strength first increased and then decreased; in the case of the same number of freeze-thaw cycles, the higher the gas content, the lower the water-cement ratio, the smaller the strength loss of concrete, the loss of mechanical properties The order of the size is: flexural strength and splitting tensile strength, dynamic elastic modulus and compressive strength. The correlation between the freeze-thaw damage and the flexural strength is good, but the correlation with the compressive strength is poor. Melt damage less than 40%, concrete resistance Intensity is not less than 70% of its initial strength.