06-10-2022, 11:19 AM
REVIBRATION
As long as the concrete is still workable (still not achieved its initial set) there is no harm if it is revibrated. Tests have shown increase in strength due to revibration. n columns and walls where surface finish is of importance, there is sometimes a tendency for blowholes to occur in the top 600 mm of a lift. The reason is that, unlike the lower layers, this top layer does not have the advantage or the weight of additional concrete on top to increase the compaction. It can be advantageous to
revibrate the top 600 mm of concrete after the initial compaction but before it achieves the initial set.
It is also observed that in hot weather concreting shrinkage cracks are reduced if the concrete pour in slabs are lightly vibrated initially and then revibrated after a
lapse of time. Revibration and refinishing helps reduce shrinkage cracks.
As long as the concrete is still workable (still not achieved its initial set) there is no harm if it is revibrated. Tests have shown increase in strength due to revibration. n columns and walls where surface finish is of importance, there is sometimes a tendency for blowholes to occur in the top 600 mm of a lift. The reason is that, unlike the lower layers, this top layer does not have the advantage or the weight of additional concrete on top to increase the compaction. It can be advantageous to
revibrate the top 600 mm of concrete after the initial compaction but before it achieves the initial set.
It is also observed that in hot weather concreting shrinkage cracks are reduced if the concrete pour in slabs are lightly vibrated initially and then revibrated after a
lapse of time. Revibration and refinishing helps reduce shrinkage cracks.