Combined effect of polypropylene fiber and silica fume on workability and carbonation resistance of concrete composite containing fly ash

A parametric experimental study has been conducted to investigate the combined effect of polypropylene fiber and silica fume on the workability and carbonation resistance of concrete composite containing fly ash. Five different fiber volume fractions, four contents of fly ash and four silica fume contents were used. The results indicate that the workability of the concrete composite becomes better and better by increasing the fly ash content. The addition of fly ash has lowered the carbonation resistance of concrete composite, and the carbonation resistance is decreasing gradually with the increase of fly ash content. Besides, the addition of silica fume can evidently improve the carbonation resistance of concrete composites containing fly ash, and the carbonation resistance is becoming better and better as the silica fume content is increasing gradually. In addition, polypropylene fiber can greatly improve the carbonation resistance of concrete composites containing fly ash and silica fume, and there is a tendency of increase in the carbonation resistance with the increase of fiber volume fraction as the fiber volume fraction is below 0.12%. However, the addition of silica fume and polypropylene fiber has a little adverse effect on the workability of the concrete composites.