微波和传统加热下混凝土劈裂抗拉性能分析

ANALYSIS OF SPLITTING TENSILE PROPERTIES OF CONCRETE UNDER MICROWAVE AND CONVENTIONAL HEATING CONDITIONS

  • 摘要: 近年来,微波辅助混凝土粗骨料回收技术因其绿色性、高效性及低损伤性引起国内外学者广泛关注。该文采用工业微波多模谐振腔及传统马弗炉对圆柱体混凝土试样进行不同条件下的加热实验,探讨了混凝土在两种加热方式下的加热效率、宏观裂纹扩展与破坏模式、劈裂抗拉强度弱化规律以及加热参数对能耗和能效的影响规律。此外,借助扫描电镜分析了微波照射下混凝土的抗拉强度弱化机理。实验结果表明:微波加热技术具有更高的加热效率,能够有效地促使裂纹沿砂浆-骨料界面扩展,从而削弱混凝土强度;并且高微波功率下混凝土加热效率更高,强度损失更大,能量消耗更少。反之,传统加热下砂浆-骨料界面结构紧凑,未出现可见裂纹,加热过程能量利用率仅1%左右。

     

    Abstract: Microwave-assisted concrete coarse aggregate recycling technology has attracted extensive attention from scholars at home and abroad due to its green, effective, and low aggregate damage recycling properties. A multi-mode microwave resonator and conventional muffle furnace were employed to heat the cylindrical concrete specimens with different energy inputs. The investigation was performed for the heating efficiency, macroscopic crack expansion, material failure mode, splitting tensile strength weakening laws, and the influence laws of heating parameters on energy consumption and on energy efficiency. In addition, the mechanism of tensile strength weakening of concrete under microwave irradiation was analyzed through the scanning electron microscopy (SEM) tests. The experimental results show that the microwave heating technology has higher heating efficiency and can effectively promote crack propagation along the mortar-aggregate interface and then weaken the concrete strength. The higher the microwave power, the higher the thermal efficiency of concrete, the greater strength loss of concrete, and the lower the energy consumption. However, the mortar-aggregate interface was still compact under conventional heating, with no visible cracks occurred, and the energy efficiency during heating process was only about 1%.

     

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