How is Vibrator Applied to Reinforced Concrete Member?

We have learned about different compaction process of concrete in previous posts. In the recent post we have discussed about over vibration of concrete. Now in this post we will learn how vibration is applied to reinforced concrete member. 


There have many difficulties in vibrating congested reinforced concrete member especially near beam and column joints or in heavily reinforced mat to column joints in column strips. These situations become worse when basement wall passes through the columns. To have compacted dense concrete having no air void in reinforced concrete member the reinforcement detailing require special attention.

The detailing should have such provision that vibrating head passes through the reinforcement. The spacing of bars should be detailed properly. Reinforcement can be grouped to have more space to permit vibrator pass through the gap freely. But the grouping width must be less than 25 cm and a spacing of 7.5 cm has to be provided between two groups. In individual group the bar spacing can be reduced up to 2/3 of nominal coarse aggregate size.

In case of closely spaced reinforcement, special care is provided to vibrate the concrete to avoid pockets or accumulation of grout. In case of properly tied and fastened reinforcement arrangement or where some portion of concrete in the member has already stiffened i.e. set vibrator can be pressed against reinforcement. But if this done to improperly supported and tied reinforced member, the formwork and internal arrangement of reinforcement may collapse.