Abstract: 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.

Key words: concrete;autogenous shrinkage;magnesium slag;fly ash;shrinkage compensation