Water tightness test was carried out for water retaining structures. The testing procedure was divided into following major works which includes clearing, water filling, testing and disposal of used water.
Cleaning of structure
- The internal surface was brushed using stiff broom until cleaned all debris in the surface was dry.
- The water retaining structure was flooded with about 75 mm of clean water and the internal surface brushed with stiff broom using the water until al surface were clean.
- After that the water was drained off and walls and floor flushed with clean water until well cleaned.
Water filling and testing
- The filling was carried out for each basin separately
- The base pit was filled with water in controlled manner by using supply pipe line
- The water was pumped to the tank in stages not exceeding one meter in 24 hours
- The dampness or leakage occurred location was marked with permanent marker
- The water was drawn off and remedial action take place
- Then procedure was followed to until maximum water level of structure.
- After that completion of filling, water level was maintained 21 days by adding water (Note : Evaporation has to be maintain with satisfactory level)
- Water level reading was taken during the this period in every 24 hours
- Remedial action was taken for defected area until the leak proof
Remedies for the water leaks
There were three types of leakages were identified. Those were leakages through the construction joints, P-cones, honeycombs. Each leakage was got the different repairing methodology with the different chemicals.
Sealing of Honeycombs
- Lanko 731- A high strength structural repair mortar for providing necessary cover to expose reinforcement and offer structural integrity to the structure.
- Polybond RP- A coating over exposed reinforcement to protect the reinforcement from corrosion.
- L-Bond – A liquid binding agent that was brushed applied to the substrate.
1. The areas where honey combing exists were hacked out to remove all weak concrete.
2. The area was thoroughly cleaned and all corrosion that had formed on the reinforcement was, wire brush and cleaned.
3. The exposed reinforcement was coated with Polybond RP so that it was protected.
4. The entire spelled areas were coated with L-Bond, which act as the key coat and creates the bond for the repair mortar.
5. The surface was patched with Lanko 731 repair mortar.
Sealing of P-cones
Product; Dave Putty
1. The area where the grout has been filled around the P-cones was removed.
2. These areas around the P-cone were filled with Dave Putty and allowed to cure.
Sealing leakage through construction joint
Product: L 21 Epoxy injection and Davco Putty
L 21 Epoxy injection was a low viscosity crack injection resin material based on modified epoxy resin and an amine hardening binder, solvent free.
Procedure of water tightness test
1. The cracks were cleaned to remove any loose particles that may cause to inhibit the flow of the epoxy.
2. Nozzles were installed into the cracks, starring from one end of the crack. The nozzles were placed at intervals of 500mm apart.
3. The length of the crack between the nozzles was sealed with Dave Putty on the surface and L 21 Epoxy injection was injected into the cracks via the nozzles. Beginning of the first nozzle, the injection was begun under pressure until material flows from the adjacent nozzle.
4. The first nozzle was then sealed and the injection began at the second nozzle.
5. Once the nozzles were removed, the holes of the nozzles were filled with Dave Putty.
6. Procedure was followed until the entire crack length was sealed
Water retaining structure has to be checked with permeability test and water absorption of concrete. That has to be monitor with long term basis that is critical with Self Compacting Concrete.