Such case happened in front of me.... on one my project that I did consulting issue for them.. the engineer order the labor to use the vibrators for compacting pile concrete.. and I reject the idea... based on logical opinion..
Concrete is usually poured after flushing borehole (pile bore). Tremie method is usually adopted for piling work. Concrete is poured through funnel/ conveyor belt sometimes. Piles are vertical or nearly vertical, concrete feed with vertical pipes will compact due to gravity. In pile foundation depth is very large. Vibrators might not work and not required since the choosen concrete will attain self compacting ability when poured through tremor.
Concrete for pilling work is designed as high-slump self-compacting mix which is capable of flowing through reinforcement cage with ease. Hence vibrators are not used for providing further compaction.
Moreover, the concrete in piles is compacted by energy derived from free falling.
If vibrators are used, the vibrated concrete may be compacted to the sides of the concrete casings which may lead to lifting up of casings.
@ Debashish Mondal sir, Also if vibrators are used aggregate will segregate. Iff aggregate are segregated mortar mix (mixture of fines and binder) will come out with sludge. Perhaps excess concrete (lower density concrete mixed with sludge) will overflow on other hand by self compacting ability concrete will get compacted adequately filling all loose pockets.
Dear Anand Kumar B.G .... Totally right.. weight of concrete did the required compaction.. But did more compacting with vibrators will effect... on the strength of concrete ... or might give negative results.. ??
Thanks for the answer...
Dear.. Debasish Mondal ... You define the case in so good way.. Thanks for your answer... But in sites the concrete used for piles are the same of other structural elements.. providing the required strength and workability.. and what happened in actual site.. So, what if the supervisor engineer didn't consider the " high-slump self-compacting mix" ... whats will be the results.. and at that time.. can we use vibrators. ????
Anand Kumar B.G ......... Right vibrators makes aggregate to segregate .. If... if we used more than the limited time....But if it used within the time limitation, then good compaction will attained.. more strength will gain....
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