微波照射后钢纤维混凝土强度劣化研究

Study on the strength weakening rule of steel fiber reinforced concrete after microwave irradiation

以抗拉强度为指标,研究微波照射后钢纤维混凝土强度的劣化规律,分别分析功率、照射时间微波作用下,钢纤维混凝土的强度劣化机理.研究表明:微波功率一定时,照射时间的延长钢纤维混凝土的强度逐渐下降,并且强度劣化速率呈降低趋势,最终钢纤维混凝土完全丧失抗拉强度,微波照射后,喷水冷却有助于钢纤维混凝土强度劣化;当微波照射时间不变时,微波功率对钢纤维混凝土的强度影响与增长照射时间有相同的影响规律.微波照射引起钢纤维混凝土的强度劣化原于混凝土中水泥胶体与钢纤维表面的化学胶着力的下降;钢纤维与混凝土接触表面上的摩擦力的弱化和钢纤维表面粗糙不平产生的机械咬合力减弱.

Based on tensile strength index, this paper studies the law of steel-fiber reinforced concrete strength degradation after microwave irradiation. The relations between the strength reduction and the microwave exposure time and microwave power level are analyzed. The experimental research shows that the longer the steel-fiber reinforced concrete is irradiated, the more its strength reduces under the equal power microwave, and meanwhile the speed of strength degradation is reduced , finally the steel-fiber reinforced concrete lose its tensile strength entirely. The cooling by spraying water after microwave irradiation leads to larger strength reduction of concrete. For the fixed irradiation time, the same result is found. The reason for steel-fiber reinforced concrete degradation induced by microwave irradiation is the decline of chemical bonding force between the surface of steel-fiber and the cement gel in concrete, the weakening of friction on the contact surface of steel fiber and the concrete, and reduction of mechanical interaction of steel fiber by its rough surface.