Combined Effect of Silica Fume and Polypropylene Fiberon Drying Shrinkage Properties of Concrete Composites Containing Fly Ash

A parametric experimental study has been conducted to investigate the combined effect of silica fume and polypropylene fiber onthe workability and dryingshrinkage of concrete composite containing fly ash. Four contents of fly ash, four silica fume contents and four different fiber volume fractions were used. The results indicate thatfly ash can not only improve the workability but also lower the dryingshrinkage of the concrete composite.The workability of the concrete compositebecomes better and betterand the dryingshrinkage strain is decreasing gradually with the increase of fly ash content. Besides, silica fume has adverse effect on both of the workability and dryingshrinkage property of concrete composite containing fly ash. With the increase of silica fume content, both of the slump and slump flow of the concrete containing fly ash are decreasing gradually, while the dryingshrinkage strainhas an increasing tendency. In addition, polypropylene fiber can greatly restrict the dryingshrinkage of concrete composite containing fly ash and silica fume, and there is a tendency of decrease in the dryingshrinkage strain with the increase of fiber volume fraction.However, polypropylene fiber has a little adverse effect on the workability of concrete composite.