The specialist contractor has carried out several major projects over recent months at Hove in Sussex, as well as Tenby and Aberdare in Wales. In all cases the cathodic protection systems were selecred by the client to both prevent corrosion and to reduce the future maintenance costs.

Cathodic protection, as a method of slowing the rate of corrosion of reinforcement in concrete, has a very successful track record. In addition to controlling the corrosion, the steel is negatively charged enabling it to repel negatively charged chloride ions, the electrochemical reactions result in the generation of alkaline hydroxyl ions at the steel surface and this, in turn, promotes repassivation and hence, corrosion protection.

Because of the unique atmosphere pervading swimming pools such structures are prone to developing accelerated concrete reinforcement corrosion in the dry ducts behind the pool walls. The problem is attributable to the high levels of chloride found in these warm and humid environments. Whilst the causes were common, Concrete Repairs Ltd were required to individually design each installation. In Hove, a titanium mesh anode was applied in a concrete overlay for the duct floor and conductive paint used for the wall areas.

At Tenby a unique discrete anode system, installed into the pool walls, projected the wall reinforcement. The anode was placed in the dummy tiles especially manufactured for the project. The cathodic protection system is energised when the pool is not in use via movement detectors and this is sufficient to give 24 hour corrosion protection. The external walls in the dry duct are protected by discrete durAnodes located in holes drilled into the beams and columns. This project is believed to be the first in the UK to employ discrete water anodes for effective and economical corrosion control.