Effects of UEA and MgO expansive agents on fracture properties of concrete
Effects of UEA and MgO expansive agents on fracture properties of concrete
复制标题
DOI：
10.1016/j.conbuildmat.2020.120245
复制
发表时间：
2020-12-10
影响因子：
7.4
通讯作者：
Zhang, Peng
中科院分区：
文献类型：
--
作者：
Guo, Jinjun;Zhang, Shiwei;Zhang, Peng
通过三点弯曲试验，研究了联合膨胀剂（UEA）和MgO膨胀剂对混凝土断裂性能的影响。通过SEM和XRD细观实验，分析了双膨胀剂对混凝土断裂性能的影响机理。结果表明，在UEA和MgO膨胀剂不同配比下，混凝土断裂参数随养护龄期的变化趋势不同。膨胀剂在28天前普遍降低混凝土的初始断裂韧性和不稳定断裂韧性，只有当UEA与MgO膨胀剂配比为2:1时，混凝土的断裂韧性才有所提高。在28 ~ 60日龄期间，掺加膨胀剂的混凝土断裂韧性的增长速度明显超过普通混凝土。在60 d时，配比为2:1的膨胀混凝土的初始断裂韧性和不稳定断裂韧性达到最大值，分别是普通混凝土的1.12倍和1.09倍。SEM测试结果表明，适量MgO膨胀剂的加入减少了水化产物与骨料之间的粘结裂缝，改善了混凝土的界面过渡区（ITZ），减少了干缩引起的裂缝。根据本研究的实验结果，可以得出UEA与MgO膨胀剂的最佳配比为2:1，以改善混凝土的断裂性能。(C) 2020 Elsevier Ltd.版权所有。
Through three-point bending test, the effects of united expansive agent (UEA) and MgO expansive agent on the fracture properties of concrete were investigated. The influence mechanism of the double expansive agents on the fracture properties of concrete was analyzed based on SEM and XRD microscopic experiments. The results indicated that the development tendencies of the concrete fracture parameters varied with the curing ages under different compounding ratios of UEA and MgO expansive agents. The expansive agents generally decreased the initial fracture toughness and unstable fracture toughness of concrete before 28 days, and the fracture toughness increased only when the compounding ratio of UEA and MgO expansive agents was 2:1. During 28 days to 60 days of age, the growth rates of concrete fracture toughness with expansive agents exceeded the ordinary concrete significantly. At 60 days, the initial fracture toughness and unstable fracture toughness of expansive concrete with the compounding ratio of 2:1 reached the maximum values, which were 1.12 times and 1.09 times to that of ordinary concrete, respectively. The SEM test results showed that addition of appropriate amount of MgO expansive agent reduced the bonding cracks between the hydration products and the aggregates, which improved the interfacial transition zone (ITZ) of concrete and reduced the cracks due to dry shrinkage. Based on the experimental results obtained in this study, it can be suggested that the optimal compounding ratio of UEA and MgO expansive agents is 2:1 for improvement in fracture properties of concrete. (C) 2020 Elsevier Ltd. All rights reserved.