Abstract
Two oval shaped reinforced concrete tanks built one over the other, exhibited significant concrete damage in addition to cracking. The annular space between the walls of the tanks are filled with man made sea water for marine life habitation. Cracks were observed on the walls and the floor slabs. It was suspected that the cracks may be active and that a change in width would occur over time, allowing access of chloride saturated sea water to the reinforcing steel.
A detailed field survey was performed to evaluate the condition of the tanks. Select cracks were monitored to determine whether they were active or dormant. Analysis such as chloride content, cover over reinforcement, water-cement ratio, air entrainment, alkali-silica reactivity, and the chemical analysis of water extracted from the coating blisters were performed. The results of the analysis are presented. The present condition of the structure is defined as safe from the structural stand point.
The existing polyurethane coating on the concrete surface in contact with man made seawater will be removed by high pressure water blasting. The areas of concrete contaminated by chlorides will be identified, removed and patched. A new multi-layered epoxy coating system will be applied over the concrete surface to act as a barrier to chloride ion intrusion.
