微膨胀和侧向约束共同作用下混凝土徐变性能和孔结构的关系

发布时间：2018-11-10 14:11

【摘要】：为了研究膨胀剂在微膨胀和侧限约束共同作用时对混凝土徐变性能的影响,以及徐变性能与孔结构变化的关系。在室内进行了膨胀剂掺量分别为4%、8%、12%的混凝土徐变试验,测试了钢管与混凝土整体纵向变形随时间的变化及孔结构的分布规律,并结合标准养护无侧向约束、密封养护无侧向约束及密封养护有侧向约束3种情况的孔结构分析,进行了不同侧向约束下的混凝土徐变试验。结果表明:随着膨胀剂掺量的增加,混凝土中孔数量、孔隙率在减少;混凝土徐变度随着膨胀剂掺量的增大而减小。限制作用下混凝土的孔隙率、平均孔径和气孔含量比无侧向约束的混凝土小;侧向限制可以明显减小混凝土徐变度。研究认为膨胀剂通过固相和液相化学反应生成钙矾石,其吸水肿胀和结晶压力作用使混凝土体积膨胀;同时在钢管侧向约束力的作用下,混凝土存在的自应力促进了进一步水化,改变了混凝土的孔结构,从而使混凝土更加致密,减小了混凝土的徐变度。
[Abstract]:In order to study the effect of expansive agent on creep behavior of concrete under the combined action of micro-expansion and lateral confinement, and the relationship between creep property and pore structure change. The creep test of concrete with 4% expansive agent and 12% concrete was carried out indoors. The variation of longitudinal deformation of steel pipe and concrete with time and the distribution of pore structure were tested, and no lateral restraint was obtained in combination with standard maintenance. The creep tests of concrete under different lateral constraints were carried out by analyzing the pore structure of sealing maintenance without lateral constraint and seal curing with lateral constraint. The results show that the number of pores and the porosity of concrete decrease with the increase of the amount of expansive agent, and the creep degree of concrete decreases with the increase of the amount of expansive agent. The porosity, average pore size and porosity content of concrete under confined action are smaller than those of concrete without lateral confinement, and the creep degree of concrete can be significantly reduced by lateral confinement. It is considered that the swelling agent produces ettringite through solid and liquid phase chemical reaction, and the swelling of water absorption and crystallization pressure make the volume of concrete expand. At the same time, under the action of lateral binding force of steel pipe, the self-stress of concrete promotes further hydration, changes the pore structure of concrete, thus makes the concrete more compact and reduces the creep degree of concrete.
【作者单位】：兰州交通大学土木工程学院;
【基金】：国家自然科学基金(51268032) 长江学者和创新团队发展计划(IRT1139) 兰州交通大学青年科学基金(2012028)资助
【分类号】：TU528.042.4

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