All about civil construction knowledge- PARAM VISIONS

Why do we have to break pile head after casting?/ Reason for breaking the pile head till cutoff level.

You might have noticed that after casting the pile, the top part of the pile is chipped to a certain level. 

Always, the head part of the pile, up to the cutoff level is broken after casting.

As you can observe in the below drawing, a tremie pipe & hopper setup is used to pour the concrete while casting the pile.

At the time of pile concreting, first, we charge the hopper with concrete.  The lock system above the tremie pipe is opened to let the concrete into the pile bore. The concrete is gradually filled in the pile bore, using this concrete batching & charging method.

The bottom end of the tremie pipe is always kept immersed in the poured concrete. In this process, the top part of the concrete gets contaminated with mud splash, bentonite slurry, & other organic impurities.

 When we complete the casting work, the sludge concrete occupies the top part of the pile. This sludge concrete is weak in its compressive strength & they are not capable to carry the designed strength.

So, a cutoff level is calculated for these piles, depending upon their depth, diameter, required design strength, & pile cap level. 

Here, the cutoff level is nothing but the bottom level of the pile cap. By chipping the pile head, we expose the pile reinforcement to have a development length (Ld ) with the pile cap.


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