Nili Mahmoud, Sasanipour Hossein, Aslani Farhad
Department of Civil Engineering, Bu-Ali Sina University, Hamedan 65178-38695, Iran.
School of Engineering, Hamedan University of Technology, Hamedan 65169-13733, Iran.
Materials (Basel). 2019 Apr 4;12(7):1120. doi: 10.3390/ma12071120.
Today, the use of recycled aggregates as a substitute for a part of the natural aggregates in concrete production is increasing. This approach is essential because the resources for natural aggregates are decreasing in the world. In the present study, the effects of recycled concrete aggregates as a partial replacement for fine (by 50%) and coarse aggregates (by 100%) were examined in the self-compacting concrete mixtures which contain air-entraining agents and silica fumes. Two series of self-compacting concrete mixes have been prepared. In the first series, fine and coarse recycled mixtures respectively with 50% and 100% replacement with air entraining agent were used. In the second series, fine recycled (with 50% replacement) and coarse recycled (with 100% replacement) were used with silica fume. The rheological properties of the self-compacting concrete (SCC) were determined using slump-flow and J-ring tests. The tests of compressive strength, tensile strength, and compressive stress-strain behavior were performed on both series. The results indicated that air-entraining agent and silica fume have an important role in stabilization of fresh properties of the mixtures. The results of tests indicated a decrease in compressive strength, modulus of elasticity, and energy absorption of concrete mixtures containing air entrained agent. Also, the results showed that complete replacement (100%) with coarse recycled material had no significant effect on mechanical strength, while replacement with 50% fine recycled material has reduced compressive strength, tensile strength, and energy absorption.
如今，在混凝土生产中使用再生骨料替代部分天然骨料的情况日益增多。这种方法至关重要，因为全球天然骨料资源正在减少。在本研究中，在含有引气剂和硅灰的自密实混凝土混合物中，研究了再生混凝土骨料分别部分替代细骨料（50%）和粗骨料（100%）的效果。制备了两组自密实混凝土混合物。在第一组中，分别使用了细骨料和粗骨料替换率为50%和100%且含有引气剂的再生混合物。在第二组中，使用了细骨料替换率为50%和粗骨料替换率为100%且含有硅灰的再生材料。通过坍落扩展度试验和J环试验测定自密实混凝土（SCC）的流变性能。对两组混合物都进行了抗压强度、抗拉强度和抗压应力 - 应变行为测试。结果表明，引气剂和硅灰对混合物新拌性能的稳定具有重要作用。试验结果表明，含有引气剂的混凝土混合物的抗压强度、弹性模量和能量吸收有所降低。此外，结果表明，粗骨料完全被再生材料替代（100%）对力学强度没有显著影响，而细骨料被50%的再生材料替代会降低抗压强度、抗拉强度和能量吸收。
