复掺减缩剂、引气剂对砂浆抗裂性能的影响

Influence of compounding shrinkage reducing agent and air entraining agent on crack resistance of cement mortar

研究了单掺引气剂、减缩剂以及将两者复合对砂浆抗裂性能的影响规律,利用SEM观察了砂浆内部以及界面过渡区的微观形貌,并相应的从收缩机理、孔结构等角度进行了分析。试验结果表明:单掺引气剂会提高砂浆的收缩率,较低掺量时可以延缓砂浆圆环的开裂;单掺减缩剂可以大幅度降低砂浆的收缩率,延缓砂浆圆环开裂。减缩剂复配引气剂后,砂浆的收缩率与单掺减缩剂时相比变化不大,圆环开裂时间得到大幅度延迟;与单掺减缩剂、引气剂相比,两者复合掺入后,砂浆的抗裂性能得到加强。

The effect of air entraining agent, shrinkage reducing agent and the mixing of them on early age cracking tendency of cement mortar was investigated.The micro-morphology of cement mortar and interracial transition zone was observed by SEM, the shrinkage mechanism and pore structure was analyzed accordingly as well.The results showed that the single doped air entraining agent could in- crease the shrinkage ratio of cement mortar and the cracking of the mortar rings was delayed by a low dosage.The shrinkage ratio was greatly reduced and the cracking of the mortar ring was delayed by doping of shrinkage reducing agent.Compared with single doped SRA, the mixture of both shrinkage reducing agent and air entraining agent can lead to a more significant delay of the cracking of mortar rings, but the shrinkage ratio changed little.Above all, crack resistance can be greatly strengthened by compounding both shrinkage reducing a- gent and air entraining agent.