Protection of reinforced concrete columns from chloride ingress in a tidal situation.
Inspection of the 70 supporting pillars at the Shell UK terminal on the River Mersey revealed localised spalling of the concrete and corrosion of the reinforcement, due mainly to chloride attack and waterborne pollutants.
A concrete repair system was sought to rectify the damage and to prevent further degradation in line with 30 year design life.
Given that the tide governed the available working and curing times, it was important to select a product which could be used within a limited time frame. Cementitious Coating 851 is ideally suited to application in marine conditions as it can be subject to immersion in as little as one hour after application, resisting early wash-off. On curing, the 2mm film of Cementitious Coating 851 forms a dense impermeable matrix with good chemical resistance and water permeability roughly equivalent to that of an extra metre of concrete cover. It also forms an outstanding barrier to chlorides, having already exceeded 16 years in an independent chloride diffusion test.