Midvaal Water Company in Stilfontein supplies potable water in bulk to an area of some 900km2 in the North West Province.When specialised joint sealing was required at one of the company’s filter units, Sika’s Sikadur-Combiflex SG system proved its worth.
The filter unit consists of pre-cast concrete slabs that form a suspended floor to carry filter sand media. Filtered water passes through nozzles in the concrete slabs to a holding sump from which it is pumped into a chemical treatment facility prior to being distributed to the surrounding areas. The project objective was to prevent the sand from passing through the joints, which would contaminate the filtered water passing through the nozzles into the sump.
Botjheng Water, a company with a core focus in water and wastewater bulk infrastructure construction, was consulted on the sealing around and between the nozzles of the filter unit. Engineers soon realised that the joint sealant originally specified would not be viable, so turned to Sika for a solution. Various product samples were supplied to Botjheng Water who conducted a variety of tests to ascertain the amount of pressure the Sika system could withstand in comparison to the site requirements. Finally the Sikadur-Combiflex SG system was the product accepted and approved.
Sikadur-Combiflex SG system consists of a modified flexible Polyolefin (FPO) waterproofing tape that is glued in place with Sikadur-31 CF, a moisture-tolerant, thixotropic advanced adhesive based on a combination of epoxy resins and special fillers. This high performance joint sealing system is suitable for expansion, construction and connection joints as well as for cracks, and once fixed to the joint, allows irregular and high movement in more than one direction, while still maintaining a high quality seal. The versatility of this product makes it suitable for many difficult situations, as was the case in this project.
Multi Contracts Specialists applied the Sikadur-Combiflex SG system to the filter unit, consisting of 24 filter segments, each made up of two filter banks. With the product consumption per filter bank measuring 38.3m, a total of 1838.4m was applied. Although Combiflex Tape is available in a variety of widths and thicknesses, the 150mm x 2mm tape specified had to be cut to 130mm wide to accommodate the site-specific requirements around and between the nozzles. Water testing was subsequently conducted resulting in all 48 filter banks passing the first test.
The Sikadur-Combiflex SG system is extremely flexible, easy to install and suitable for both dry and damp concrete surfaces. It performs well within a wide range of temperatures and is weather and water resistant as well as root resistant. Besides being resistant to many chemical substances, this outstanding product comes with approval for potable water suitability.
Evidently this joint sealing system was so impressive, that various similar filter units at Midvaal Water Company are all scheduled for resealing in the near future, with Sika’s reliable Sikadur-Combiflex SG system.