Using a range of products from a company providing processing materials will add to the success of a new power station.
In May 2013, Sika AG, a globally active speciality chemicals company that supplies the building and construction industry as well as manufacturing industries with processing materials, commenced with a large project at Eskom’s Medupi Power Station in Lephalale, Limpopo.
Engineers at Nyeleti Consulting specified numerous Sika specialist products for repairs and protection of various areas of the plant. In a joint venture, contractors BKV Holdings, along with Multi Contracts Specialists, were subcontracted for the application of Sika products, which included supporting products for substrate preparations and final coating products from the Sikagard and Sikalastic-800 series.
For general crack repairs, Sikadur-52 ZA, a low-viscosity injection liquid based on high-strength epoxy resins, was used. It not only forms an effective barrier against water infiltration and corrosion-promoting elements, but also structurally bonds the concrete sections together.
In turn, SikaGard-720 EpoCem, a three-part, epoxy-modified, cementitious, fine-textured mortar was used for re-profiling and as a moisture barrier. This thixotropic product is easy to apply and protects concrete, particularly in aggressive chemical environments.
Once surface preparations were complete, engineers decided that a 200m2 external sump floor would be the first area to be coated with the Sikalastic-841 ST system. The area was first primed with Sikafloor-161, an economical, low-viscosity epoxy resin providing good penetration and excellent bond strength. To reduce pinholing and to create better mechanical key, a layer of Sikadur-931 Sand was applied as broadcast over the primer.
Thereafter, a coating of Sikalastic-841 ST was machine-sprayed over the sump floor. This elastic, pure-polyurea membrane, suitable for waterproofing and anti-corrosion applications on concrete, steel and many other substrates, is UV-resistant and offers crack-bridging properties. Sikalastic-841 ST is applicable in temperatures from -15o to 70o and performs in constant temperatures from -30o to 120o, is 100% solids with zero-VOC, is suitable for use in a wide variety of applications while its fast reactivity and cure time allow for almost immediate return to service.
Upon completion and inspection of the sump floor, engineers were so impressed with this system that it was decided to use Sikalastic-841 ST as the primary coating system for all major areas at the plant, instead of Sikagard-63N, as originally specified.
A second product used from the Sikalastic-800 range, was Sikalastic-844 XT, a modified polyurea membrane with very similar properties to Sikalastic-841 ST. It is designed for seamless protection of concrete or steel where exposure to high acidic or alkaline chemical concentrations is present.
This huge project is still ongoing with almost 10 000m2 having already been coated with Sika’s products. Once fully operational, Medupi Power Station will be the fourth largest coal plant in the world and one of the biggest dry-cooled power stations in the world.