基于超声波测试的冻融循环作用下混凝土强度损伤演变研究

Study on Damage Evolution of Concrete Strength Under Freeze-thaw Cycles Action Based on Ultrasonic Tests

针对高寒地区混凝土抗冻耐久性问题,在混凝土中加入不同掺量的粉煤灰研究其抗冻性能,通过非金属声波检测仪进行冻融循环过程中混凝土强度无损测试,研究了冻融循环作用下混凝土强度损伤和动弹性力学参数的演化特征,分析了冻融循环过程中混凝土声波波速与力学性能变化规律。研究结果表明:掺入引气剂能够提高混凝土的抗冻性,相同引气剂掺量下,粉煤灰掺量为10%的混凝土抗冻性较好;冻融循环过程中,超声波纵波波速、横波波速与动弹性模量、动剪切模量均随着冻融循环次数的增加呈相似性衰减,且存在较高相关性。

In view of the problem of frost resistance durability of concrete in alpine area,the frost resistance of concrete was studied by adding fly ash with different content.By using non-metallic acoustic wave detector to test the strength of concrete during freeze-thaw process,the characteristics of strength damage and dynamic elastic mechanical parameters evolution of concrete under freeze-thaw cycle were studied.The change law of concrete acoustic wave speed and mechanical properties during the freeze-thaw cycle were analyzed.The results show that the frost resistance of concrete can be improved by adding air entraining agent,and the frost resistance of concrete with 10%fly ash content is better than that of 20%fly ash content under the same air entraining agent.The ultrasonic longitudinal wave velocity and shear wave velocity,dynamic elastic modulus and dynamic shear modulus attenuate similarly with the increase of freeze-thaw cycle times during freeze-thaw process,and there is a correlation between them.