减缩剂对水泥砂浆塑性收缩开裂的影响及机理分析  

Effect of shrinkage-reducing admixture on the plastic shrinkage cracking of mortar and mechanism analysis

作　　者：光鉴淼 邹小童 GUANG Jianmiao;ZOU Xiaotong(Jiangsu Sobute New Materials Co.Ltd.,Nanjing 211100,China;Jiangsu Shuanglong Corporation,Nanjing 211100,China)

机构地区：[1]江苏苏博特新材料股份有限公司,江苏南京211100 [2]江苏双龙集团有限公司,江苏南京211100

出　　处：《新型建筑材料》2023年第9期57-61,共5页New Building Materials

基　　金：科技创新资金项目(ZB22108)。

摘　　要：研究了不同掺量的减缩剂对水泥砂浆塑性收缩开裂的影响,通过探究其对砂浆水分蒸发量、泌水量、水化热、表面张力和毛细管负压的影响,揭示其缓解水泥砂浆塑性收缩开裂机理。结果表明,当减缩剂掺量为4%时,缓解塑性收缩开裂效果最强,分别使开裂面积、平均和最大裂缝宽度减小52.1%、48.4%和35.0%;减缩剂明显降低水泥水化放热峰值并推迟其出现的时间,其延缓作用随着掺量的增加逐步增强。减缩剂的掺入使得砂浆水分蒸发量降低、泌水量增大,从而使毛细管负压诱导期延长;同时,降低了体系孔溶液表面张力,延缓毛细管负压的发展,缓解塑性收缩开裂。The effect of shrinkage-reducing admixture(SRA)on plastic shrinkage cracking of cement mortar was studied,and the working mechanism was revealed by investigating its effect on moisture evaporation,water leakage,hydration heat,surface tension and capillary pressure.The results show that when the dosage of SRA is 4%,the cracking area,average and maximum crack width of mortar is reduced by 52.1%,48.4% and 35.0%,respectively.The shrinkage-reducing admixture significantly reduced the peak of cement hydration exothermic heat and delayed its occurrence,and its retarding effect gradually increased with the increase of the dosage.In addition,SRA prolongs the induction period of capillary pressure by reducing the moisture evaporation of mortar and increasing the water secretion.Meanwhile,it delays the development of capillary pressure by reducing the surface tension of the pore solution,thus mitigating the plastic shrinkage cracking.

关 键 词：减缩剂 水泥砂浆 塑性收缩开裂 表面张力 毛细管负压 

分 类 号：TU528.042[建筑科学—建筑技术科学]