超声波法评价不同类型混凝土高温后性能和参数的比选

Evaluation of performance of different types of concrete after high temperature and comparison-selection of parameters by ultrasonic method

为研究超声波法评价不同类型混凝土高温后性能的普适性,对普通混凝土、高强混凝土和掺聚丙烯纤维的高强混凝土进行200℃、400℃、600℃、800℃的高温试验,对比分析了3种不同类型混凝土的相对波速、相对幅值和损伤度3个参数与受热温度、抗压强度损失率和抗折强度损失率的关系。结果表明:对于3种不同类型的混凝土,采用损伤度和相对波速评价混凝土高温后的性能具有同一性结果,其中,损伤度的拟合值与实验值的相关性最大,能直观地反映出混凝土的受损程度;而对于相对幅值,拟合值与实验值的相关性最小,对3种不同类型混凝土的评价结果差别较大,不具有同一性。

In order to research the universality of ultrasonic method in performance evaluation of different types of concretes after high temperature, experimental studies are carried out on the C35 concrete, C50 concrete with and without polypropylene fibers, under different high temperatures up to 200℃, 400℃, 600℃and 800℃. The relationship of heating temperature, loss rate of compressive strength and loss rate of flexural strength with relative wave velocity, relative amplitude and damage degree of three types of concretes are analyzed. The results show that the evaluation method using damage degree or relative wave velocity leads to identity results, the correlation of damage degree between fitted value and experimental value is strongest and damage degree directly shows the extent of concrete damage. In comparison to the former two methods, the 3rd evaluation method using relative amplitude leads to minimum correlation between fitted value and experimental value, which provides results with great difference for three different types of concrete and has non-identity.