Concrete Water Tank Relining and Repair Case Study

These images show the concrete tank before any preparation work and then after preparation and concrete water tank relining and repair. The concrete tank was fully relined with Acothane DW.

This underground, concrete, water storage tank is located at a university and sized at approximately 12m x 3m x 3m. The fibre glass lining that had been previously applied to the floor and part of the side walls had reached the end of its useful life due to general deterioration, water entrapment and subsequent de-bonding:

Bitumen paint had also been applied to some areas of the walls and soffits of the tank. The paint had started to deteriorate due to low film build and subsequent de-bonding:

Concrete Tank Relining from Acothane DW

The university needed the tank to be offline for the minimum amount of time possible but required a durable coating that was suitable for drinking water, after looking at several options Acothane DW was specified for the following reasons:-

  • Approved for use in Public Water Supplies – Regulation 31(4)(a)
  • Fast curing time so a quick return to service
  • Flexible with excellent elongation properties
  • Tough – high impact and abrasion resistance
  • Solvent Free Polyurethane
  • Easy to clean making future maintenance simple
  • Exceptional track record

A suitable sub-contractor was chosen to prepare the tank relining and apply the Acothane DW coating.

All of the previous coatings and surface contaminants were removed from the concrete water tank and any broken or loose concrete was removed. The internal surfaces were then lightly abrasive blasted to remove all laitance and curing agents.

Concrete Water Tank Reline Process

A fairing coat (1-3mm) of cementitious lining was then applied to the water tank, finished with a damp sponge to create a profiled surface. The fairing coat was allowed to cure for the specified time prior to application of Acothane DW LV Sealer. The seams, edges and intricate areas of the concrete tank were then ‘stripe coated’ twice with Acothane DW to ensure that these difficult areas were fully encapsulated before the full coating was applied.

Two coats of Acothane DW was then applied, Cream followed by Blue (a second ‘stripe coat’ was applied after the first full coat of Cream Acothane DW)) to give a uniform even thickness of a nominal 1000 Microns.

To meet DWI regulations for drinking water the Acothane DW coating was then left to cure for 7 days before disinfection and refilling by the water treatment company used by the university.