Once again Sika’s world-class products came to the fore when engineers were faced with either demolishing a sub-standard concrete floor slab or finding a solution to the setback. A new Dischem Store had been planned as an extension to Pietermaritzburg’s upmarket Liberty Midlands Mall. However, when it was discovered that the new suspended floor slab had a structural defect, PDNA Structural Engineers looked to Sika’s state-of-the-art CarboDur system to solve the problem. The slab required external reinforcing for strengthening and increased load capacity, and it also had to meet the requirements for the shop services to be installed. The main contractor was Aveng Grinaker.

Sika CarboDur Plates are pultruded carbon fibre reinforced polymer (CFRP) laminates designed for strengthening concrete, timber and masonry structures. The laminates are bonded onto the structure as external reinforcement, using Sikadur-30, a thixotropic, structural two-part adhesive, based on a combination of epoxy resins and special filler. Sika CarboDur Plates are non-corrosive and lightweight, providing very high strength, outstanding fatigue resistance and excellent durability. Easily transported in rolls, the plates have unlimited lengths so no joints are required, have low overall thickness and are very easy to install, especially overhead. Further advantages of Sika CarboDur Plates include: combinations of high strength and modulus of elasticity; minimal preparation necessary; and the pultrusion process ensures clean edges with no exposed fibres. The innovative Sika Carbodur Plates and Carbon Fibre Wrap systems, which are used to repair structural damage caused by fire, vehicle impact, and even earthquakes, boast worldwide endorsement, making the engineer’s specification for this project an easy decision.

Load tests were conducted to ensure the product could withstand the necessary loads and needless to say, the engineers were highly impressed with the results. The contract could continue and eventually 1,144m of Sika CarboDur Plates S512 and 69 kits of Sikadur-30 were used to strengthen the slab. The second phase of the project involved an application of SikaTop-Armatec 110 EpoCem (172 kits), a cement-based, epoxy-modified, three-component, anti-corrosion coating and bonding agent, providing good adhesion to concrete and steel, and high mechanical strength.

This was followed by an application of SikaTop Seal-107 ZA (400 kits), a two-part, polymer-modified, cementitious, waterproofing slurry comprising of a liquid polymer and a cement-based mix, incorporating special admixtures. This easy to apply product requires no water, provides very good adhesion and protects concrete against carbonation and water penetration. It is used for waterproofing structures, protecting against chloride and carbonation attack and as a general pore or blowhole filler. It is suitable for interior and exterior waterproofing and can be used in basements, cellars, reservoirs and potable water tanks. It is non-corrosive to steel or iron and is overpaintable.

Time limits were the main challenge in this project which, having commenced in November 2011, needed to be completed in time for the December Christmas shopping rush. The urgency of the project necessitated the employment of two sub-contractors, namely, Freysinet and Structural Maintenance, as major penalties were to be implemented if the scheduled completion date was not met. Both contractors worked concurrently in order to complete the two phases timeously.

Liberty Midlands Mall was able to open its new Dischem shop in time, secure in the knowledge that the project was successfully completed. This solution demonstrates the double efficacy of Sika products; whereby superb quality solved an urgent structural problem, and ease of application allowed time constraints to be overcome.