The ACA Auckland meeting held at the Surrey Hotel, Grey Lynn, on 20th March was addressed by Bryant Wells, Technical Development Manager, LiquiMix P/L, Brisbane. After refreshments in the lounge, the topic outlined by Bryant was “Polyurea – extending the life of concrete and steel assets”, with particular emphasis on the life extension of water industry assets.
Bryant explained how millions of dollars are spent by municipal councils, industrial and mining companies to develop infrastructure to process potable water, waste water and sewage. Cracks that develop in any concrete structures can cause leaks and damage to the assets. Chemicals in waste water and sewage, such as sulphuric acid, attack the cement leaving expose aggregate and possibly exposing steel rebar within the structure.
After outlining the chemistry of polyurea coatings Bryant emphasised that the chemical formulation chosen for pure polyurea was critical for good performance as concrete and steel structure linings. A well-applied pure polyurea coating cures quickly, it is smooth,seamless, and it has excellent abrasion resistance. The polyurea coating also bridges cracks in concrete, it has good chemical resistance and it is elastomeric. The pure polyurea coating is applied over an epoxy primer.
Bryant outlined the three-step life extension system for remediation of older concrete and steel assets (the 3 P’s) which are: Preparation of the substrate; Priming the surface;
Protecting the asset with polyurea. If the three-step PPP system is properly employed with good QA throughout application then a polyurea lining will ensure that a water facility asset will be protected for 30+ years. Bryant then described a number of recent case studies involving water plant assets, including the remediation of a waste water clarifier and potable water tanks. The case studies were well-illustrated with on-site videos of the polyurea lining application process.
Following an extensive Q&A session, the Chair of the meeting, Raed El Sarraf, thanked Bryant for his excellent presentation, and then the attendees retired for refreshments.