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-  2018 

活性粉末混凝土高温后超声研究及微观分析

Keywords: 活性粉末混凝土 高温 超声波法 抗压强度损失率 扫描电镜
RPC high temperature ultrasonic testing compressive strength loss rate SEM

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Abstract:

为研究超声波法对活性粉末混凝土(RPC)高温后性能评价的普适性,进行100 ℃、200 ℃、300 ℃、400 ℃、500 ℃、600 ℃、700 ℃和800 ℃的高温试验,对比分析了相对波速、损伤度、相对主频和相对幅值4个参数与受热温度、抗压强度损失率的关系,并利用扫描电镜(SEM)研究了不同高温后RPC的微观结构变化.结果表明:对于活性粉末混凝土,采用损伤度和相对波速评价其高温后性能相关性较好,其中,拟合值与试验值相关性最好的是损伤度,能较准确地反映RPC的受损程度;而相对主频和相对幅值,其拟合值与实验值的相关性最小,评价结果差别较大;随着温度的升高,RPC内部缺陷开始增多,基体与纤维界面出现裂纹,微观结构不断恶化,抗压强度损失率增大.
In order to investigate the adaptation of ultrasonic test in evaluating the performance of reactive powder concrete (RPC) after high temperature exposure, the high temperature tests under 100 ℃, 200 ℃, 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃ and 800 ℃ were performed. The relationship between the four parameters (relative wave velocity, damage degree, relative frequency and relative amplitude) and temperature as well as compressive strength loss rate was analyzed. The microstructure of RPC was also studied by scanning electron microscopy (SEM) technique after exposure to high temperature. The results showed that adopting the parameters of damage degree and relative velocity to evaluate the performance of RPC after high temperature was better than adopting the parameters of relative frequency and relative amplitude. The correlation of the fitting value of damage degree with experimental value was the largest, which can accurately reflect the damage degree of RPC. On the contrary, the fitting value of relative frequency and relative amplitude showed little correlation with the experimental value. With the increasing of the elevated temperature, the internal defects of RPC exacerbated, and the cracks at the bonding interface of fiber and the matrix occurred gradually, which illustrated that the micro-structure of RPC deteriorated constantly and the loss rate of compressive strength increased gradually.

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