Inspection and permit assessment of swimming pool in Västervik

Problem statement

Invator Sverige AB was commissioned by Västervik Municipality to inspect a swimming pool in Västervik. The pool was built in reinforced concrete in 1974, corresponding today to concrete class C30/35. The reason for the inspection was extensive corrosion of the reinforcement and cracking of the concrete. The cause of the problems was chlorides from the pool water in combination with neglected maintenance.

Outcome

The overall assessment of the inspection indicates that many parts of the building show extensive corrosion of the reinforcement and that restoration measures are required. Columns, beams and wall structures should be repaired. In some cases, the reinforcement is rusted and must be replaced with new where possible, or the structural element must be reinforced. In short, chloride-infected concrete was removed, rusted and damaged reinforcement was replaced and in some cases the concrete was repaired locally, in other cases new pre-cast concrete was made. After the renovation, concrete surfaces were impregnated to better resist possible future attacks.

Solution

The inspection has been carried out in the following way; first, all the documents provided were reviewed, the work was comprehensively planned before coming to the site. In total the inspection took 4 days on site. On the first day, the work was planned in more detail after a visual inspection was carried out. Then defects were investigated on site where we divided the investigation into columns, beams, walls and details. The investigation was largely carried out visually by tapping, but also with georadar (GPR), cover layer meters and ultrasound (tomography) and EKP (electrical potential measurement). Sampling was also carried out, including chlorides and the carbonation depth of the concrete.

The inspection has followed Invators three-step procedure, i.e. from level 1 with initial investigations up to and including level 3 when we also carried out load-bearing calculations. However, it should be mentioned that the basin has been examined from the outside, no beam cracking of tiles or inspection of the inside of the basin has been carried out. Furthermore, no examination of the floor has been carried out from the top. From the underside, beam cracking and sampling of chlorides and carbonation depths were carried out. The inspection then led to concrete repair measures and method descriptions, as well as follow-up of offers from contractors.

Equipment

Standards

EN 1504-9:2008 – Concrete structures – Products and systems for protection and repair – Part 9: General principles for the selection of products and systems.