废混凝土骨料和废砖骨料再生混凝土的模型化研究

In order to observe and study the crack development of recycled concrete more clearly and conveniently, modeled concrete specimens were prepared from normal aggregate concrete and recycled aggregate concrete which used recycled waste concrete aggregate and recycled waste brick aggregate as the aggregate respectively, according to the concept of two-dimensionalized concrete. The specimens were subjected to a compressive loading, and during the loading process, images of the front and back surfaces and the speckle pattern of different scales were captured with a normal digital camera and a high resolution camera, respectively to obtain the global and local strain fields. By analyzing the global strain field and the local strain field near the interfacial transition zones (ITZ), the crack development process and damage evolution mechanism of the modeled recycled concrete were revealed. The results show that the elastic modulus of the modeled concrete with the waste brick aggregate is the smallest, but its compressive strength is higher than that prepared with the recycled waste concrete aggregate. The global strain field of the recycled concrete shows that the strain concentrates around the old mortar area, while the local strain field shows that cracks develop in the old ITZ first, and then in the new ITZ. For the modeled concrete prepared with the waste brick aggregate, it is found that strain concentration first appears in the ITZ between the brick aggregate and the new mortar. The cracks do not develop along this ITZ, but run through the waste brick aggregate. The strain concentration in the ITZ is weakened due to the redistribution of stress.