How to Stop Running Water Coming from the Basement Raft via Concrete Jacketing


Following is an account along with pictures of every step, explaining how to fix a concrete basement raft leakage located 5 feet under water-table, caused due to faulty concreting. Actually the contractor did not tie the basement raft (floor) with a platform of pillar/column. Twenty years ago when he made the basement, the water-table was lower than the raft level which is why his mistake was not noticed at that time. But later when the water-table rose in D.H.A. Karachi due to water-logging, water started to oz out into the basement flooring. For some reason, the house took a long time and water started to pour into the basement before it was completed. Three attempts were made to waterproof the basement in two decades, but nobody tried to find out the actual cause and fixed it. Instead every waterproofer put another layer of CC floor, mixed with waterproofing chemicals over the flooring. This worked for a few months, before the water to come out of the new flooring again. These attempts increase the floor level up to a meter and thus reducing the height of basement.

Since the actual cause of leakage was hidden under the three layers of flooring, it was not possible to locate it without removing the entire one meter thick flooring of basement. When I was given this assignment, I first of all removed the whole flooring to investigate the raft and concrete joints. After removing the water through powerful pumps, we saw water coming out into the basement from near a pillar platform. Upon investigating it further, it was found that the whole joint of raft with a pillar platform was not tied properly and infect a cavity was left (1' wide and 10' long in "L" shape). The only way to fix such a huge void in basement raft is to do 'concrete jacketing'.

But the concrete jacketing cannot be done unless the water level is kept well below, the freshly poured concrete to allow the new concrete to set. In this case the leakage point was a few feet under the water-table, and the water may have burst out of the newly poured concrete before the concrete retains considerable strength to hold it. Even small water pressure would make the newly poured concrete to remain 'unset' and the whole procedure will fail. If that happens, the whole procedure needs to be repeated but after cutting and removing the concrete of previous attempt. Thus; all care and precautions should be taken to insure that the jacketing has to be successful in first attempt.

It requires two pipes to be placed inside the cavity; one pipe is connected to the vacuum suction pump that will keep sucking the water for as long the newly concrete is not set (usually 48 hours) and second pipe is the overflow pipe which is placed as a back-up, just in case the suction pipe fails-- either due to blockage of the opening of suction pipe that is submersed under the crush or the suction pump failure. After some 48 hours, the newly poured concrete has enough strength to stop the leakage sustaining the water pressure. Such a procedure is applied when the cavity from which the water is coming is wide and large enough for the usual water proofing methods to plug. In this case since the raft level was some 5 feet under the water-table, thus the water was coming out with speed. Following is the picture account of each and every step and can be used as a working manual for fixing leakages in concrete basements-- made well under the water-table where water pressure is involved.


We see the platform of a pillar along the front wall wall. The problem is that this platform is not joined with the basement floor (raft) and there is this cavity that is some 1' wide and some 10' long in "L" shape.
We see the platform of a pillar along the front wall wall. The problem is that this platform is not joined with the basement floor (raft) and there is this cavity that is some 1' wide and some 10' long in "L" shape. | Source
This is the close up of the cavity. We see a black pipe submersed into water. This pipe is connected with a vacuum suction pump.
This is the close up of the cavity. We see a black pipe submersed into water. This pipe is connected with a vacuum suction pump. | Source
We see that the steel has been tied, the vacuum suction pump is installed with its pipe going down into the cavity. Also another pipe we see which is the over-flow pipe.
We see that the steel has been tied, the vacuum suction pump is installed with its pipe going down into the cavity. Also another pipe we see which is the over-flow pipe. | Source
This close-up shows the cavity filled with crush so that the newly poured concrete would stay over the crush while the crush would provide the cushion for letting the water coming from leakage to collect and pumped out by the suction pump.
This close-up shows the cavity filled with crush so that the newly poured concrete would stay over the crush while the crush would provide the cushion for letting the water coming from leakage to collect and pumped out by the suction pump. | Source
In this picture, one can see the cavity being filled with crush.
In this picture, one can see the cavity being filled with crush. | Source
The close up shows the suction pipe as well as the over-flow pipe. Both have the mouth which has netting to protect from sucking anything else except water.
The close up shows the suction pipe as well as the over-flow pipe. Both have the mouth which has netting to protect from sucking anything else except water. | Source
Here we see that a plastic sheet is placed over the crush around the pipes to ensure that the newly poured concrete does not reach the opening of the pipes and choke them.
Here we see that a plastic sheet is placed over the crush around the pipes to ensure that the newly poured concrete does not reach the opening of the pipes and choke them. | Source
Now a mixture of fine sand, cement and soda has been put over the crush. This mixture is fast drying and will set fast and provide a barrier between the water and the newly poured concrete and help stop water coming up to touch the fresh concrete.
Now a mixture of fine sand, cement and soda has been put over the crush. This mixture is fast drying and will set fast and provide a barrier between the water and the newly poured concrete and help stop water coming up to touch the fresh concrete. | Source
We see that the whole cavity which was first filled with crush, is now covered by the mixture of fine sand, cement and soda.
We see that the whole cavity which was first filled with crush, is now covered by the mixture of fine sand, cement and soda. | Source
Here we see that finally the shuttering has been erected and concrete pouring started.
Here we see that finally the shuttering has been erected and concrete pouring started. | Source
Here we see that the concrete pouring is almost completed except a foot or so left.
Here we see that the concrete pouring is almost completed except a foot or so left. | Source
Here is the picture of the finished work. The suction pump did not fail due to choking of its mouth which is why a over-flow pipe is placed as a back-up. What we see here is a job completed by the book. The pipes will be cut and holes plugged.
Here is the picture of the finished work. The suction pump did not fail due to choking of its mouth which is why a over-flow pipe is placed as a back-up. What we see here is a job completed by the book. The pipes will be cut and holes plugged. | Source

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Comments 1 comment

Tufail Shah 13 months ago

Dear Arshad Bhi, i constructed my basement. it is half way through. i read your precious article and now i need to discuss certain point with you.

can i get your id or phone number.

will really appreciate.

mailtotufail@gmail.com

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