膨胀剂和钢管侧限对混凝土徐变应变的影响

发布时间：2018-04-15 02:16

本文选题：侧限 + 膨胀剂　；参考：《复合材料学报》2017年09期

【摘要】：为了研究不同膨胀剂质量分数和钢管侧限对混凝土徐变应变的影响,共进行了12组有、无钢管侧限的混凝土徐变试验。结果表明:加载龄期到480天的试验试件中,有钢管侧限的混凝土徐变应变约是无钢管侧限徐变应变的0.175~0.181倍,钢管侧限大大降低了混凝土的徐变应变。同时进行了三种不同质量分数膨胀剂(质量分数分别为4%、8%和12%)的混凝土徐变试验。结果表明:无论有、无钢管侧限的混凝土结构,膨胀剂质量分数对混凝土徐变应变的影响关系为:质量分数4%时,结构徐变应变均最大;质量分数为8%时,结构徐变应变次之;质量分数为12%时,结构徐变应变最小。通过钢管侧限对混凝土的套箍效应计算分析表明,在混凝土结构加载应力相同情况下,有钢管侧限的混凝土结构应力比小于无侧限的混凝土结构应力比;钢管侧限对混凝土的侧向约束增加,限制了混凝土纵向变形;随着应力比的减小,结构徐变变形减小。同时应用扫描电镜二次电子成像分析膨胀剂的作用机制得出:水泥浆中膨胀剂水化产生粗棒状、互相交叉的三硫型硫铝酸钙(AFt)结晶体,填充在原来被溶液占据的小孔里,使水泥石更密实。
[Abstract]:In order to study the effect of different mass fraction of expansive agent and lateral limit of steel tube on creep strain of concrete, 12 groups of concrete creep tests without lateral limit of steel tube were carried out.The results show that the creep strain of concrete with lateral limit of steel tube is about 0.175 ~ 0.181 times that of that without lateral limit of steel tube, and the lateral limit of steel tube greatly reduces the creep strain of concrete.At the same time, concrete creep tests were carried out with three kinds of expansive agents with different mass fraction (mass fraction of 4% and 12% respectively).The results show that the influence of mass fraction of expansive agent on creep strain of concrete structure without lateral limit of steel tube is as follows: when mass fraction is 4, creep strain of structure is the largest, and creep strain of structure is next when mass fraction is 8.When the mass fraction is 12, the creep strain of the structure is minimum.Through the calculation and analysis of the hoop effect on concrete by the lateral limit of steel tube, it is shown that the stress ratio of the concrete structure with the lateral limit of steel tube is smaller than that of the concrete structure with no lateral limit under the same loading stress of the concrete structure.The lateral restraint of steel tube on concrete limits limits the longitudinal deformation of concrete, and the creep deformation decreases with the decrease of stress ratio.At the same time, the mechanism of the expansion agent was analyzed by scanning electron microscope (SEM) secondary electron imaging. It was concluded that the hydration of the expansive agent in the cement slurry produced coarse rod shaped, intersecting calcium sulphoaluminate (AFT) crystal, which was filled in the pore occupied by the original solution.Make the cement stone more dense.
【作者单位】：兰州交通大学甘肃省道路桥梁与地下工程重点实验室;兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室;
【基金】：青年人才托举工程(2015QNRC001) 飞天学者特聘计划陇原青年创新人才扶持计划长江学者和创新团队发展计划滚动支持(IRT_15R29) 甘肃省基础研究创新群体(145RJIA332) 兰州交通大学(201606)优秀平台资助甘肃省高校协同创新科技团队支持计划资助(2017C-08)
【分类号】：TU528

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