Epoxy Coating for Buried Concrete Manholes
THE CHALLENGE
The client was having difficulties with 5 concrete buried water interceptors. Originally, there was no protective coating installed and the concrete surface was left exposed. As a result, the chambers were degrading, and signs of water ingress were starting to show. A new coating was required to return the tanks to working order.
OUR SOLUTION
We decided to apply Raven 405, an industry-leading epoxy lining system. This well-respected coating has been protecting assets in the water and wastewater industry for over 35 years.
After an initial inspection of the tanks, a closed-cell polyurethane resin was injected into the degraded holes in the concrete. When the resin comes into contact with water, it expands, filling the voids and preventing more water from entering the tank.
Once the resin had cured, our operatives used a diamond grinder on any defects in the concrete surface, resulting in a smooth profile for the coating to adhere to. The area was then high-pressure water jetted, this provided a clean surface free of any friable material, laitance, or surface contaminants.
We installed a cementitious concrete fillet detail before applying 2 coats of a penetrating epoxy primer. This primer greatly improved the adhesion to the substrate and prevented outgassing during the application process.
Using our 7.5-ton lorry mounted fixed-ratio plural component pump, we spray applied Raven 405 to the required thickness and have successfully relined the asset and extended its lifespan, protecting it from H2S attack and further degradation.
Once the coating had been applied, we conducted a high-voltage spark test on the surface to detect any pinholes or holidays present. These were then corrected by hand and retested, resulting in totally continuous film across the lower internal surface.
The client was extremely happy with the result.
