Waterproofing solutions were applied to ensure the structural soundness of KwaMashu Wastewater Treatment Works.
For the rehabilitation of the KwaMashu Wastewater Treatment Works, about 25km north of Durban, Aecom Consulting Engineers specified half a dozen Sika products, which were applied in three separate phases of the project.
The first application involved waterproofing of the roof slabs, which measured approximately 900m2. The contractor, Industrial Linings Natal, prepared the surface area by grinding and pressure cleaning, prior to an application of Sikalastic-EP Primer II, a two-part, low viscosity, epoxy-polyamine resin.
This multi-purpose primer is easy to apply, with short waiting times, and provides good penetration and high bond strength. It is suitable for internal and external use and can be used as a primer for all PUR and polyurea systems.
This was followed by a 1,5 mm layer of Sikalastic-841 ST, a two-part, fast-curing pure polyurea membrane designed for machine application only. Suitable for waterproofing and anticorrosion applications on concrete, steel and other substrates, it contains 100% solids with zero volatile organic compounds (VOCs), is UV-resistant and provides excellent crack-bridging properties.
The second application of Sika products for strengthening the roof slabs was done by AMFRA Maintenance Services. After diamond grinding the roof surface, a preparation layer of Sikadur-30 (eight kits) was applied. Based on a combination of epoxy resins and special filler, this structural two-part adhesive is easy to mix and apply and offers high creep resistance under permanent load.
The shrinkage-free hardening of Sikadur-30 is not affected by high humidity, a significant factor for this particular project. It provides initial and ultimate mechanical resistance and is impermeable to liquids and water vapour.
To complete this phase, a layer of Sika CarboDur Plates (S512 x 116 metres) was applied over the adhesive. These pultruded, carbon fibre reinforced polymer (CFRP) laminates are designed for external reinforcement of concrete, timber and masonry structures.
Internationally approved, this product is used for applications including load increase, damage to structural elements, service improvements such as stress reduction in steel reinforcement, as well as for changes to a structural system. Supplied in lightweight rolls, Sika CarboDur Plates are easily installed, while their high strength and outstanding fatigue resistance provide excellent durability.
The third and final stage of the project involved joint sealing on the five digester tanks. Fakazi Construction applied 80m x 2mm of the Sikadur-Combiflex SG system, which consists of a modified flexible Polyolefin (FPO) waterproofing tape with advanced adhesion, to each tank.
The tank surfaces were prepared by scabbling prior to applying a coating of Sikadur-31 CF Normal, a moisture-tolerant, thixotropic, structural two-part adhesive based on a combination of epoxy resins and special fillers. This high-strength adhesive and repair mortar offers very good chemical resistance.
When fixed to a joint, the versatile Sikadur-Combiflex SG sealing system allows for irregular and high movement in more than one direction, whilst still maintaining a high-quality seal. It is easy to install, extremely flexible, weather- and water-resistant and is suitable for use in many difficult situations.
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