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掺膨胀剂水泥砂浆的早期约束应力及徐变性能
作者: 强1 2  华1 2 陆安群1 2  倩1 2 刘加平1 3 
单位:1. 高性能土木工程材料国家重点实验室 江苏省建筑科学研究院有限公司 南京 210008 2. 江苏苏博特新材料股份有限公司 南京 211103 3. 东南大学材料科学与工程学院 南京 211189 
关键词:双圆环 膨胀剂 砂浆 约束应力 徐变 
分类号:TU528.55
出版年,卷(期):页码:2016,44(11):1602-1608
DOI:10.14062/j.issn.0454-5648.2016.11.09
摘要:

采用改进的双圆环约束方法,测试了掺入氧化钙-硫酸钙复合膨胀剂水泥砂浆在膨胀及收缩全过程中的约束应力,结合极限拉伸试验评估了砂浆的开裂风险,并初步建立了砂浆早期徐变的计算模型。结果表明:在密封及干燥养护条件下,掺入膨胀剂可以有效延迟拉应力的产生时间,并降低拉应力数值,从而降低水泥基材料的开裂风险;根据砂浆环与约束钢环的变形协调关系可以计算砂浆的早期徐变变形,砂浆在早期发生的徐变大,使得膨胀剂在这一阶段产生的膨胀由于徐变而消耗,从而降低产生的约束压应力,减弱补偿收缩的效果。
 

Restrained stress development of cement mortar with expansive agent during the whole process (including expansion and shrinkage) was investigated by improved dual rings restraint tests, providing the quantitative information about cracking risk using ultimate tensile strength. In addition, an analytical model was also proposed to compute the creep at early ages. The results show that the addition of expansive agent delays the generation of tensile stress and reduces the tensile stress, thus reducing a cracking risk under sealed and drying conditions. The early creep was determined based on “deformation-fit” of mortar ring and steel rings. The expansion occurred at early days does not work due to the big creep, leading to a lower restrained compressive stress and a weaker effectiveness of shrinkage compensation.
 

基金项目:
国家杰出青年科学基金(51225801);国家自然科学基金(51578268) 资助项目
作者简介:
夏 强(1989—),男,硕士。
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