盐冻作用下掺粉煤灰混凝土超声波波速测强理论模型

在室内模拟了盐冻(5%Na2SO4)作用下掺粉煤灰水工混凝土抗冻性试验,探究了超声波波速及抗压强度随冻融循环次数的变化规律及波速测强理论模型。结果表明,超声波波速及抗压强度随着冻融循环次数的增加而不断下降,冻融150次后内部冻融损伤不断积累加快,掺入粉煤灰对抗冻性产生不利影响;建立了波速测强指数关系理论模型及相对超声波波速与抗压强度损失率之间的指数关系式,发现当抗压强度损失率达50%时,相对波速降为85%,这为运用超声波无损检测手段评价盐冻条件下掺粉煤灰水工混凝土的抗压强度提供了理论模型依据。

Theoretical Model of Ultrasonic Wave Velocity and Compressive Strength Measurement of Concrete Mixed with Fly Ash under Salt Freezing

By simulating the frost-resistance test of fly-ash concrete with fly ash (5% Na2SO4) in the laboratory, the variation law of ultrasonic wave velocity and compressive strength with the number of freeze-thaw cycles and the theoretical model of wave velocity and strength measurement were investigated. The test results show that the ultrasonic wave velocity and compressive strength decline with the increase of the number of freeze-thaw cycles. After 150 times, the internal freeze-thaw damage continues to be accumulated and accelerated. The fly ash has a detrimental effect on the frost-resistance. The theoretical model of wave velocity and compressive strength measurement the exponential relationship between the relative ultrasonic wave velocity and the loss rate of compressive strength was established. When the loss rate of compressive strength is 50%, the relative wave velocity is reduced to 85%, which provides a theoretical basis for evaluating the compressive strength of hydraulic concrete mixed with different fly ash contents using ultrasonic nondestructive testing methods under the condition of salt freezing.