减水剂和膨胀剂对混凝土收缩的影响研究

The Influence of Water Reducing Agents and Expansion Agents on Concrete Shrinkage

目的:研究减水剂和膨胀剂对混凝土收缩的影响.方法:以水泥、粉煤灰、细砂、碎石、水、不同类型的减水剂和膨胀剂为原材料,按照设定配合比制作混凝土试件,在试件早期收缩过程中测量其变形值,进而计算出收缩率作为试验指标.结果:不同类型减水剂改性的混凝土试件收缩率从大到小依次为早强型、标准型、缓凝型,且混凝土试件收缩率随减水剂掺量的增加而下降;不同类型膨胀剂改性的混凝土试件收缩率从大到小依次为氧化钙类、硫铝酸钙类、氧化镁类,且混凝土试件收缩率随减水剂掺量的增加而下降.结论:缓凝型减水剂掺量为1.2%、氧化镁类膨胀剂掺量为12%时,为最佳混凝土制备条件.

Objective:To study the influence of water reducer and expansion agent on concrete shrinkage.Methods:using cement,fly ash,fine sand,crushed stone,water,different types of water reducer and ex⁃pansion agent as raw materials,concrete specimens were made according to the set mix proportion.The deformation value was measured during the early shrinkage process of the specimens,and then the shrink⁃age rate was calculated as the test index.Results:the shrinkage rates of different types of superplasticizer modified concrete specimens were early strength type,standard type and retarding type from large to small,and the shrinkage rate of concrete specimens decreased with the increase of the amount of super⁃plasticizer;the shrinkage rates of different types of expansive agent modified concrete specimens are cal⁃cium oxide,calcium sulphoaluminate and magnesium oxide from large to small,and the shrinkage rate of concrete specimens decreases with the increase of water reducing agent content.Conclusion:1.2%retard⁃ing water reducer and 12%magnesium oxide expansive agent are the best concrete preparation conditions.