06-10-2022, 10:08 AM
OVER VIBRATION
A good cohesive concrete mix will withstand over vibration but a lean concrete mix will segregate and result in concrete of non-uniform strength, quality and durability. Concrete will be weaker at the top and would develop cracks and will not perform to the extent desired.Over vibration results in excess laitance· on the top surface which in case of columns and wall tops can be easily removed by chipping while preparing the construction joint.
In case of slabs, however, this removal is impossible. Therefore excessive laitance formation must be avoided either by using a cohesive mix not likely to bleed and I or not overworking the surface with the poker vibrator. However, in cases this is not completely possible, after the compaction is over the top surface can be scooped
up once again using a fork (panja) and coarse aggregate brought on to the surface and then levelled and compacted with a float.
A good cohesive concrete mix will withstand over vibration but a lean concrete mix will segregate and result in concrete of non-uniform strength, quality and durability. Concrete will be weaker at the top and would develop cracks and will not perform to the extent desired.Over vibration results in excess laitance· on the top surface which in case of columns and wall tops can be easily removed by chipping while preparing the construction joint.
In case of slabs, however, this removal is impossible. Therefore excessive laitance formation must be avoided either by using a cohesive mix not likely to bleed and I or not overworking the surface with the poker vibrator. However, in cases this is not completely possible, after the compaction is over the top surface can be scooped
up once again using a fork (panja) and coarse aggregate brought on to the surface and then levelled and compacted with a float.