Construction World October 2017

ROADS & BRIDGES

ECONOMICAL alternative for HAMMANSKRAAL project Thanks to Kaytech, South Africa’s leading manufacturer of non- woven 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, the engineer consulted with Kaytech’s Danie Herbst who, with the assistance of Tensar, recommended the installation of TriAx TX 160 as 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

First layer of TriAx laid over the bidim as subgrade stabilisation.

34

CONSTRUCTION WORLD OCTOBER 2017