DDR were engaged by Vopak to refurbish four tanks. The tanks had been constructed on an aggregate base with a concrete ring beam that extends around the edge of the tank base.
The concrete ring beam is 550mm wide. The lip of the tank is placed on the concrete ring beam on a section that extends approximately 300mm across the beam. The join between the tank and the concrete ring beam is composed of an asphalt pre-mix and a cementitious grout at the external join, both approximately 150mm wide each.
After 10 years of service, a noticeable deterioration in the condition of the grout had been experienced.
Tank base sealing is a critical protection and failure of the tank base seal is the most common cause of tank failure due to underfloor corrosion at the perimeter. Without treatment, this would have led to a deterioration in the tank and premature failure.
