Shrinkage of fibre and reinforced fibre concrete beams in hot-dry climate

The influence of steel fibre inclusion on the shrinkage of 16 full-size plain and reinforced concrete beams was assessed. Shrinkage measurements, at three levels over the depth of the beams, were carried out for 200 days. Half of the beams were cured in a controlled laboratory environment and the other half cured under hot, dry and windy climatic conditions.

Test results show that under laboratory curing conditions adding 1% by volume of steel fibres reduced the ultimate shrinkage at the top, mid-height, and bottom of the plain concrete by 16, 23, and 28%, respectively. However, in the reinforced concrete beam the presence of longitudinal reinforcement rendered it less significant.

Under the uncontrolled severe curing environment, the addition of 1% by volume of fibres produced a reduction of 30% in shrinkage at the bottom level of both the plain and the reinforced concrete beams. At the top level, however, the geometry constraints and the compaction techniques influenced the fibre contribution to shrinkage.