It's Not the Pipe, It's the Joint That Leaks
Inspired by the late Nesimi Çimen's folk song "Bedenimde değil ruhumda var sızı", I wanted to direct this article towards concrete and the construction sector. Today, the external appearance of concrete comes out smooth due to both the formwork and the components that enter the concrete.
Segregation in concrete is almost non-existent. When concrete is properly compacted, its water impermeability decreases significantly, but water ingress enters the structure through concrete joints.
Whether any product will be used at concrete joints should be designed during the construction phase. If it will be used, necessary measures must be taken before the concrete is poured.
The measures to be taken at joints should be examined by project designers, owners, contractors, and building inspection organizations.
Tunnels pay the highest cost for damage caused by concrete joints. Tunnels are exposed to serious water pressure. New Austrian Tunneling Method (NATM) type tunnel is a tunneling technique widely used in our country.
To provide brief information; in the 19th century, tunnel methods were named according to the country in which they were used. This method was first used by Prof. Dr. Ladislaus von Rabcewicz. Rabcewicz filed a patent application for the NATM technique in 1948.
The technique's real dissemination occurred after 1964. The working principle is simply drilling and blasting technique. However, the Austrians also made systematic contributions to the method such as systematic bolting and in-situ measurement.As in the raft-diaphragm wall connections of reinforced concrete structures, in NATM tunnels too, joints that may form in concrete are an extremely important and problematic condition. NATM lengths are approximately 8 meters. Concrete thickness reaches approximately 1 meter.
PVC water stop tape application is not possible for joints (it can be used in arch and invert connections). To ensure water tightness from joints formed in the crown, the use of "water-swelling tapes" is a more appropriate solution.
If concrete thickness is more than 40 cm, using at least two rows of water-swelling tapes will give better results. We can apply bentonite-based water-swelling tapes by anchoring them into the concrete.
Although this is a debated topic, bentonite-based water-swelling tapes already break apart and disperse. For this reason, there is no problem in their application by anchoring them into the concrete at approximately 1 meter intervals.
Water-swelling tapes to be applied at concrete joints should be installed before the concrete is poured during construction.
If not used, it is impossible to put them in place afterwards. To cut off water coming from these areas, polyurethane injection is generally performed, which is quite costly.
Analysis of costs incurred to stop water leakage from concrete joints:
In conclusion;
In structures such as elevator pits, underground structures, dams, tunnels and similar buildings, water infiltrates the structure due to problems created by joints at column-wall connections, deck areas, construction errors and other causes. The necessary repairs to seal incoming water are costly and may not yield definitive results. In structures like tunnels, the cost incurred reaches millions of dollars. To minimize these costs, the measures to be taken at the beginning should be planned and implemented. Cem Ercan - Civil Engineer / Project and Technical Sales Manager - EmülzerAdvertisement
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