The upgrading of The Paarl Waste Water Treatment Works, in the Western Cape, lead to a first for Sika SA, when its new, state-of-the-art waterproofing product was used. Drakenstein Municipality awarded the contract for this large-scale project to engineering company Aurecon, in association with Lyners Engineering. Sika was the preferred supplier for a number of high quality construction products, including its new waterproofing product, Sika-Waterbars.

After successful completion of the Paarl Waste Water Treatment Works Phase One, civil engineering company, Exeo Khokela was awarded the contract for Phase Two, an upgrading project to further increase the capacity of the treatment works. Construction included a new clarifier, a bio-reactor erected in an area previously used as a maturation pond, associated concrete chambers, the installation of new water and irrigation pipes, and a new office building. A unique feature of this project was the construction of a bird viewing station for the client, as the treatment works is situated in a natural area that is rich in bird life.

For the first time in South Africa, Sika’s top-of-the-range waterproofing product, Sika-Waterbars were used: over 2900m were applied under all construction joints to prevent contamination of sub-soils in the area. These flexible waterstops, based on plasticized PVC, are ideally suited to seal construction and expansion joints in all water-retaining structures, as well as basements, underground car parks and tunnels. Sika-Waterbars provide excellent durability even under high water pressure, and are supplied in various sizes and types, depending on their usage. They provide easy, on-site welding, and their excellent workability resulted in the resident project engineer to state: “Sika-Waterbars are the best!”

The second phase of the project included concrete repairs, achieved by first applying Sikatop Armatec 110 EpoCem, a high quality cement-based, epoxy-modified bonding agent. This was followed by Sika MonoTop-615 HB, a high build, cementitious, polymer modified, one component, repair and reprofiling mortar containing silica fume. Designed for thick layer concrete repairs, this excellent, thixotropic product with adjustable consistency, provides good mechanical strength as well as resistance to water and chloride penetration and may be applied using the wet spray method. A similar product, Sika MonoTop-620, pore sealer and leveling mortar, was used for fine concrete repairs and for skimming up of blowholes.

For casting new concrete onto old, Sika AnchorFix-2, a solvent- and styrene-free, epoxy acrylate based, two-part anchoring adhesive, was used to bond steel dowelling rods into old concrete. This fast-curing, non-sag product, provides high load capacity and is suitable for use in all grades of rebars, threaded rods, bolts, concrete, solid masonry and steel.

For bonding of steel into old concrete, Sikadur-31 CF Normal, a moisture-tolerant, thixotropic, structural, two-part adhesive and repair mortar was the product of choice. High traffic areas were grouted with Sikadur-42 ZA, a self-leveling, solvent-free, three-component fluid grout. Both of these products are based on a combination of epoxy resins and special fillers, and provide high initial and ultimate mechanical strength. They are easy to use, suitable for dry and damp concrete surfaces, harden without shrinkage, and offer excellent abrasion and chemical resistance. Sika Grout 212, a cement-based, fluid, expanding grout, was applied under all machine base plates. Providing rapid strength development and high final strengths, this non-corrosive grout expands by gas generation whilst still in the plastic state of curing. Used for repairs and filling was Sikadur-43 ZA, a solvent-free, three-component, repair and filling mortar, based on a combination of epoxy resins and selected high strength aggregates. After mixing, it forms a trowelable mortar with good adhesion to dry or damp cementitious substrates, and provides rapid, shrinkage-free hardening and high mechanical strength.

Subcontractors, AMAC Sealants, were responsible for all sealing aspects of the project. Joint sealing of the water retaining structures necessitated the use of 2400m of Sika’s high performance Sikadur-Combiflex System which consists of a FPO (Flexible Polyoelifin) bandage and a suitable epoxy adhesive, in this case, SikaFlex-11 FC+ which is a one-part, moisture-curing, elastic joint sealant and multipurpose adhesive based on polyurethane. This easy-to-install, extremely flexible system, suitable for dry and damp concrete surfaces, provides excellent adhesion to many materials. It is fast curing, weather and water-resistant, offers good chemical resistance and due to its versatility, is suitable for many difficult situations.

Flooring joints were primed using SikaPrimer-3 N, which is based on an epoxy-polyurethane solvent. This was followed by an application of SikaFlex PRO-3 WF, a moisture-curing, one-part, elastic sealant, based on polyurethane. It is ideally suited for wastewater and sewage treatment works as well as for joints in contact with potable water or surfaces in the food industry. It provides bubble-free curing and very good mechanical and chemical resistance.

The clarifier’s launder was coated with SikaGard-720 EpoCem ZA, a three-part, epoxy-modified, cementitious, fine-textured mortar, providing excellent protection of concrete in aggressive environments. This was followed by the application of Sikagard-63 N, a solvent-free, two-part, epoxy resin coating, providing excellent chemical and mechanical resistance. These high quality Sika coatings will provide long-lasting protection of the clarifier.

Having commenced in January 2011, this large-scale project is scheduled for completion in March 2012, but due to the huge amount of mass concrete required, contractors have found they were running behind schedule, necessitating the implementation of overtime in order to catch up.

With its technically advanced product, Sika-Waterbars, in use for the first time in SA, The Paarl Waste Water Treatment Works has been a unique contract for Sika S.A. News of its outstanding workability has quickly spread, resulting in Sika-Waterbars being specified in numerous Western Cape projects.

Since Sika products have played such an important role in this project, Drakenstein Municipality is guaranteed that its Paarl Waste Water Treatment Works will be functioning optimally for many years to come.