Amjad,

I think it is used to stabilize the sides of bore hole.

Regards

It is a common practice in the construction of bored piles by adding a

cement plug before concreting of bored piles takes place. One of the

possible explanations is that the cement grout serves as a barrier and

protects fresh concrete from being washed away by water inside pile bore.

The cement grout helps to set aside water when the first batch of concrete

is poured down from the tremie pipe. As such, the quality of fresh concrete

is anticipated not to be seriously affected by water and this helps to

improve toe imperfection problem.