溶蚀混凝土力学性能退化的试验研究

An experimental study on the degradation of mechanical properties of leached concrete

通过实验室试验研究了不同配合比混凝土力学性能随溶蚀时间的演化规律.试验设计变量主要为水灰比和骨料体积率,采用硝酸铵溶液加速混凝土溶蚀过程.试验结果表明:酚酞指示剂法能够较准确地表征混凝土的溶蚀深度,溶蚀深度近似与溶蚀时间的平方根成线性关系.混凝土弹性模量、抗压强度和劈拉强度均随着溶蚀时间的增长而减小,水灰比和骨料体积率对它们的减小速率有较大影响.与弹性模量相比,溶蚀对抗压强度和劈拉强度影响更大.当溶蚀损伤变量小于0.6时,溶蚀混凝土抗压强度模型与试验结果良好吻合.

Through a laboratory test,the variations of the mechanical properties of leached concrete of different mixture proportions with leaching time are studied.In the test,the main design variables include the water/cement ratio and the aggregate volume fraction and ammonium nitrate solution is used to accelerate the leaching process.The experimental results demonstrate that the phenolphthalein method can characterize the leaching depth in concrete comparatively accurately.The leaching depth is approximately proportional to the square root of leaching time.The elastic modulus,compressive strength,and splitting tensile strength of concrete decrease with leaching time.The water/cement ratio and the aggregate volume fraction have a larger influence on their percentages of decrease.Compared with the elastic modulus,leaching exerts a more significant influence on the compressive strength and the splitting tensile strength.When the leaching damage variable is smaller than 0.6,the compressive strength model of leached concrete is in good agreement with experimental results.