Construction World November 2015

PROJECTS AND CONTRACTS

DOUBLE SOLUTION TO LEISURE BAY Located between Pretoria and Centurion is the new Leisure Bay development where two of Kaytech’s top quality products successfully solved a drainage and stability problem in an embankment. The 56- unit, residential complex constructed by Zoned Earth Development Company, is uniquely situated overlooking Leisure Bay Lake, a natural dam fed by water from an underground spring.

Since the development is built in a cutting, a retaining wall was crucial in order to secure a three to four metre embankment left by the excavation. Having noticed a significant amount of water seepage from the embankment and realising that reinforcement of the fill material behind the retaining wall was vital, GFC Consulting Engi- neers contacted Christiaan van Wyk at Kaytech for advice. Van Wyk had no hesitation in recommending Flo-Drain and RockGrid PC as the ideal products for the project. Flo-Drain is a ready-made system consisting of a Flownet drainage core encased in a filter jacket of Kaytech’s renowned bidim geotextile. Supplied in lightweight 30 m rolls, Flo-Drain is easy to transport, flexible and simple to install. Varying heights of Flo-Drain were placed vertically behind the >

ABOVE: Rockgrid PC reinforces the embank- ment’s retaining wall.

LEFT: Flo-Drain installed behind the retaining wall.

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retaining wall, and connected to a Geopipe at the base of the fin. No stone was required for this drainage application. Compared to a conventional aggregate drain, Flo-Drain provides numerous advantages and may be installed in a wide variety of appli- cations to greatly reduce the water table or to intercept seepage. It is the most economical solution to almost any subsoil drainage problem. For reinforcement and support behind the retaining wall, Rock- Grid PC 100/100 was installed horizontally in the layerworks of the backfill material. This composite, reinforcing geotextile consists of a nonwoven layer in conjunction with high tenacity, bi-axially orientated multi-filament polyester yarns, the combination of which guarantees its unique characteristics. The nonwoven layer provides not only protection to the high tenacity yarns but vital in-plane drainage capacitry to relieve pore water pressure in the fill material. Compared to woven fabrics, polyethylene grids or polypropylene grids, the high tensile modulus of RockGrid PC provides far superior reinforcement characteristics withminimum creep deformation. It may be installed wherever low-bearing capacity soils are encountered and, being manufactured in South Africa, RockGrid PC is more economical than any imported alternative.

CONSTRUCTION WORLD NOVEMBER 2015