再生混凝土单轴受压下多重界面过渡区的破坏机理研究

为研究再生粗骨料混凝土在单轴受压荷载下的破坏特性,使用数字图像相关技术记录混凝土立方体在破坏过程中的应变变化规律,并结合显微硬度测试、背散射电子成像技术等观测手段对界面过渡区的宽度和孔隙率进行定量表征。试验结果表明,分别经骨料强化和砂浆强化后,再生混凝土的抗压强度较未处理试样提升了17.86%和35.55%,说明砂浆强化更有利于提升再生混凝土的抗压强度。骨料强化可以提升老砂浆显微硬度值,降低老骨料-老砂浆界面过渡区孔隙率;砂浆强化可以提升新砂浆显微硬度值,降低老骨料-新砂浆界面过渡区以及新-老砂浆界面过渡区的孔隙率。经强化处理后的特定界面产生贯通裂缝的概率降低。

Failure Mechanism of Multi-Interfacial Transition Zones of Recycled Concrete under Uniaxial Compression

To study the failure characteristics of recycled coarse aggregate concrete under uniaxial compression, the strain change law of concrete cube in the failure process was recorded by digital image correlation technology, and the width and porosity of interfacial transition zones were characterized by microhardness test and backscattered electron imaging. The experimental results show that the compressive strength of recycled concrete increases by 17.86% and 35.55% compared with untreated samples after aggregate reinforcement and mortar reinforcement, respectively. It indicates that mortar reinforcement is more helpful for improving the compressive strength of recycled concrete. The microhardness of the old mortar increases, and the porosity of the interface transition zone between old aggregate and old mortar is reduced by aggregate reinforcement. The microhardness of new mortar increases, and the porosity of the interface transition zone between old aggregate and new mortar and between old mortar and new mortar is reduced by mortar reinforcement. The probability of passing penetrating cracks decreases for reinforcement interfaces.