THE PROBLEM
The concrete effluent bund had been severely attacked as a result of constant exposure to sugars, chemicals and the elements. As a result the concrete had been severely eroded, leaving exposed aggregates and an unsealed surface that could not be cleaned.
SOLUTION
Because of the elevated temperatures which the bund lining would be exposed to, including steam cleaning the only available solution was the installation of a 9mm polyurethane screed from Sika.
Initially the bund was thoroughly cleaned by method of hot washing to remove starch and sugar contamination that was present, which left in place would have been detrimental to the adhesion of the new bund lining.
Once clean the concrete was prepared by method of vacuum controlled scabbling and diamond grinding to remove loosed aggregates and reach sound concrete.
A new stainless steel sump was installed in conjunction with new falls to drains. These were installed using a polymer modified screed. This was primed in two coats using a damp tolerant epoxy primer, with the second coat being fully dressed with quartz aggregate to ensue excellent adhesion of the polyurethane screed.
When resin floors and bund linings are subjected to steam cleaning, an important consideration is thermal shock. The rapid change in temperature that this creates can cause a thin film coating to de-bond from the substrate. For this reason we selected to choose a 9mm polyurethane screed as the most suitable form of bund lining, as the thickness of the material dissipates the heat from cleaning, preventing de-bonding from occurring.
Sikafloor Purcem 20 was installed to all horizontal surfaces and Sikafloor 29 used to cove and render all vertical surfaces. All coved and rendered surfaces were then sealed using Sikafloor Purcem 31 – something many contractors omit to save cost. However we undertake this as standard due to the porosity of the coving material in an unsealed state. This was of particular importance in this installation given the aggressive chemicals involved.
Finally the interface between the new stainless steel sump was sealed using a flexible polyurethane jointing compound. This is essential in order to prevent cracking as a result of the different expansion potentials of the two materials, especially when subjected to rapid heating as a result of exposure to hot liquids.
This was a particularly challenging project due to the external location and frequent leaks from plant and equipment, however the finished result makes it all worth while.
