Thanks to Kaytech, South Africa’s leading manufacturer of nonwoven geotextiles, the rural Moretele Local Municipality in North West Province was afforded massive savings on a subgrade stabilisation project.
The municipality, lying to the north west of Hammanskraal, consists of 26 wards, each comprising 74 villages and plots that are connected by a low bearing road network. When a new road was under construction between the villages of Mathibestad and Makapanstad, CV Chabane & Associates concluded that it was not feasible to apply the conventional method of placing and compacting a depth of more than 1.5 metres of dump rock over the challenging clayey subgrade material.
Seeking an alternative design
Seeking an alternative design, the engineer consulted with Kaytech’s Danie Herbst who, with the assistance of Tensar, recommended the installation of TriAx TX 160as a stabilisation geogrid, and bidim A2 as the geotextile separation below.Performance trials have shown a mechanically stabilised layer (MSL) using TriAx reduces the thickness of the sub-base layers required and increases the design life of the road.
TriAx is produced from an extruded sheet of polypropylene that is punched with an array of holes and stretched to create its unique triangular structure. As a multi-axial geogrid, TriAx incorporates several characteristics which combine to create an optimised structure that out performs any bi-axial geogrid in trafficking applications. By providing near-uniform stiffness through 360 degrees, TriAx is a truly multi-directional product with near isotropic properties. When combined with a suitable aggregate,through aggregate confinement and interlockTriAx produces a mechanically stabilised layer with exceptional performance.
Manufactured in Kaytech’s ISO 9001 accredited facility in Atlantis, Cape Town, bidim is a continuous filament, nonwoven, needlepunched geotextile that meets the most stringent civil engineering and industrial specifications. Over the last decade, by processing over 26 million kilograms of high-grade polyester (from discarded cooldrink bottles), Kaytech is able to manufacture eco-friendly, A-gradebidim from 100% recycled material. Through the years, bidim has remained the best, general-purpose geotextile in Africa.
An initial separation layer of bidim A2 was laid onto the clay subgrade and then covered withTriAx Tx 160 which through its unique mechanically stabilising function effectively reduces the amount of rockfill required to provide adequate load support. The rockfill layer was then overlaid with bidim A2 to separate the rockfill and selected layers above, thus also creating a drainage layer whereby water can pass through the rockfill without influencing the selected layers.
Completion of the project
Upon completion of the project, the contractor, KTS General Trader had installed 8 568 m2 of bidim A2 (equivalent to over 25 000 recycled plastic cooldrink bottles) and 9 520 m2 of TriAx TX 160. Having no prior experience in TriAx installations, the contractor undertook a brief training session from Kaytech, and installed the product with great efficiency, allowing further construction of the road to continue.
This was an extremely economical project that proved highly beneficial to the Moretele Local Municipality.