Micromechanical damage analysis and engineering performance of concrete with colloidal nano-silica and demolished concrete aggregates
Micromechanical damage analysis and engineering performance of concrete with colloidal nano-silica and demolished concrete aggregates
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DOI：
10.1016/j.conbuildmat.2018.03.197
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发表时间：
2018-05-20
影响因子：
7.4
通讯作者：
Guler, Zeynel
中科院分区：
文献类型：
--
作者：
Erdem, Savas;Hanbay, Serap;Guler, Zeynel
在本研究中，精心制备了含有天然和再生粗骨料以及不同比例纳米二氧化硅的不同混凝土样品，以研究与材料行为相关的微观结构，并定量表征快速动态断裂后的断裂面。第一个试样100%采用天然骨料，第二个试样100%采用再生粗骨料。在其他试样中，分别使用0.5%、1%和1.5%的纳米二氧化硅和100%的再生粗骨料。对所有试件进行了一系列测试，包括抗压和抗弯强度、无损超声、冲击和水渗透测试。利用扫描电镜（SEM）、x射线计算机断层扫描结合图像分析和激光垂直干涉测量技术对纳米二氧化硅和某些混合物的冲击损伤断口表面进行了表征。结果表明，再生粗骨料削弱了天然粗骨料混凝土的力学性能，提高了天然粗骨料混凝土的透水性。然而，经定量x射线光谱微化学分析证实，这种减少可以通过在混凝土中加入纳米二氧化硅来缓解，并加入回收的粗骨料。此外，从断口表面分析也得出纳米二氧化硅在宏观上减少了混凝土的孔隙量，使混凝土的多孔性降低。这反过来又可能刺激增韧机制和裂纹挠曲，导致在快速动态断裂事件中微粗糙度值低但抗冲击性高。(C) 2018 Elsevier Ltd.版权所有。
In this study, different samples of concrete, containing natural and recycled coarse aggregates and different ratios of nano-silica, were delicately prepared to examine the micro-structure associated material behaviour, and to quantitatively characterize the fracture surfaces after fast dynamic fracture. The first specimen includes 100% of natural aggregates and for the second one, 100% of recycled coarse aggregates were used only. In the other specimens, 0.5%, 1% and 1.5% of nano-silica together with 100% of recycled coarse aggregates were used, respectively. A number of tests including compressive and flexural strength, non-destructive ultrasonic, impact and water penetration tests were conducted for all specimens. Furthermore, scanning electron microscopy (SEM), X-ray computed tomography coupled with image analysis and laser vertical interferometry were employed for the characterization of nano-silica and the impact damaged fracture surfaces of some mixtures. According to the results, recycled coarse aggregate weakened the mechanical properties of the natural coarse aggregate concrete and increased the water permeability. However, it has been demonstrated that this reduction can be mitigated by adding nano-silica into concrete, incorporating recycled coarse aggregate as confirmed by the quantitative Xray spectroscopy micro-chemical analysis. In addition, it was also concluded from the fractographical surface analysis that nano-silica reduces the pore amount and produces the concrete less porous at the macroscopic level. This, in turn, may stimulate toughening mechanism and crack deflection, leading to low micro-roughness number but high impact resistance during the fast dynamic fracture event. (C) 2018 Elsevier Ltd. All rights reserved.