材料期刊网

为了探索镁渣与粉煤灰复掺对混凝土自生收缩的作用规律,设计正交试验方案研究了混凝土的自生收缩特性,微观分析掺合料的形貌与作用机理.结果表明:镁渣和粉煤灰对混凝土的自生收缩具有显著的抑制效应,镁渣与粉煤灰的掺量由(10%,15%)增加到(40%,30%),混凝土180 d的自生收缩变形减少约44.0%;混凝土自生收缩在镁渣掺量为30%~40%区间上的极差较镁渣掺量为10%~20%区间上的极差增大3.5倍,混凝土自生收缩变形的敏感性在镁渣掺量高时相对较大;混凝土的自生收缩变形主要发生在早期,28 d就完成了测定龄期内总自生收缩变形的65.0%~80.0%,早期是混凝土收缩变形控制的重要阶段;自生收缩的模型预测值与实测值间的偏差小,可用于复掺镁渣粉煤灰混凝土自生收缩的分析与预测.

In order to explore the effect of magnesium slag and fly ash on autogenous shrinkage of concrete, a scheme of orthogonal test was designed with magnesium slag content and fly ash replacement ratio as variable factors.The autogenous shrinkage property of concrete was studied, and the micro morphology and action mechanism of the admixture were analyzed meanwhile.Experimental results show that magnesium slag and fly ash have significant inhibitory effect on autogenous shrinkage of concrete.The autogenous shrinkage of concrete at 180 d is reduced about 44.0% with the increase of the content of magnesium slag and fly ash from (10%, 15%) to (40%, 30%).The interval range of the concrete autogenous shrinkage increase 3.5 times when the interval of magnesium slag content changes from 10%-20% to 30%-40%.The sensitivity of concrete autogenous shrinkage to magnesium slag is relatively large when the magnesium slag content is high.The autogenous shrinkage of concrete mainly occurs in the early stage, 65.0%-80.0% of the total autogenous shrinkage of concrete has been generated in 28 d, the early stage is important in the control of concrete shrinkage deformation.The deviation between the predicted and measured values is small, therefore the model can be used for the analysis and prediction of autogenous shrinkage of concrete with magnesium slag and fly ash.