Wang Shenglin, Zhu Baolong
Department of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621000, China.
Materials (Basel). 2021 Mar 16;14(6):1446. doi: 10.3390/ma14061446.
In recent years, recycled aggregate concrete (RAC) has become a research hotspot in the field of urban construction because of its resource utilization of construction waste. However, compared with original concrete, its strength is still low, which requires additional nano-SiO (NS) and fiber. In order to study the mechanism of strength improvement of RAC, this paper takes NS and polyvinyl alcohol (PVA) fiber as variable parameters; uniaxial and triaxial compression tests were carried out on RAC with PVA fiber and NS, and the mechanical properties of RAC were investigated The result shows that within the range of 3% NS content, an increase in the NS substitution rate causes the mechanical properties of RAC to improve significantly. The compressive strength of RAC increases again after adding PVA fiber; through a SEM (scanning electron microscopy) analysis of the specimen, it was found that the NS filled the micro-pores and micro-cracks in the RAC, and the PVA fiber changed the contact range between recycled aggregate and mortar, so the microstructure of the material was more compact. The mechanism of RAC strength improvement is explained in the microcosmic view.
近年来，再生骨料混凝土（RAC）因其对建筑垃圾的资源利用而成为城市建设领域的研究热点。然而，与原生混凝土相比，其强度仍然较低，这就需要添加纳米二氧化硅（NS）和纤维。为了研究RAC强度提高的机理，本文以NS和聚乙烯醇（PVA）纤维为可变参数；对含PVA纤维和NS的RAC进行了单轴和三轴压缩试验，并研究了RAC的力学性能。结果表明，在NS含量为3%的范围内，NS替代率的增加会使RAC的力学性能显著提高。添加PVA纤维后，RAC的抗压强度再次提高；通过对试件的扫描电子显微镜（SEM）分析发现，NS填充了RAC中的微孔和微裂缝，PVA纤维改变了再生骨料与砂浆之间的接触范围，从而使材料的微观结构更加致密。从微观角度解释了RAC强度提高的机理。
