During construction of Raceway Industrial Park, in Germiston, Gauteng, a unique Kaytech geotextile solved a severe subgrade stabilisation problem.
When Advance Projects was awarded the contract to construct a platform onto which the new warehouse would be erected, the company was unaware that the geotechnical report on existing in-situ conditions was sub-standard. Confronted with variable soil conditions, it soon became evident to the contractor that surrounding projects had used this site as a ‘borrow pit’ for all their rubble and low-grade soils.
Difficult working conditions on site were rendered virtually untenable when sub-surface water and heavy rains wreaked havoc on excavation attempts, with heavy machinery getting stuck in the already weak material. The contractor persevered however, constructing layer upon layer a number of times without success.
It was at this stage of the project that Kaytech was consulted. At a site meeting held with BSM Baker Consulting and Advance Projects, Kaytech’s technical field staff realised that this was an ideal situation for a high strength RockGrid PC to prove its efficacy. They also explained what amount of fill material and layerworks on site would be ideal to cover the RockGrid PC layer to place it under sufficient tension.
The first composite reinforcing geotextile to be manufactured in South Africa, RockGrid PC consists of a nonwoven layer in conjunction with high tenacity, bi-axially orientated, multifilament polyester yarns, the combination of which guarantees the unique characteristics of the product. The high tensile modulus of RockGrid PC provides excellent reinforcement characteristics and minimum creep deformation compared to polyethylene or polypropylene grids or woven fabrics.
When the technical field staff’s recommendation was accepted, Kaytech engineers were consulted to double check that RockGrid PC would indeed solve the problem. The 100 x 100 kN/m grade of RockGrid PC was considered most appropriate. One of the special features of this product is its polyester, nonwoven fleece component which offers high resistance to installation stresses as well as optimum hydraulic characteristics. Only RockGrid PC provides sufficient drainage capacity and, due to its water transmissivity, it facilitates the reduction of pore water pressure and improves shear characteristics, thereby increasing stability. Ideal advantages for the problems encountered at Raceway Industrial Park.
On completion of the project, 29 000m2 of RockGrid PC 100/100 had been installed allowing the contractor to rapidly construct the required platform without using the expensive conventional method of importing dump rock and exporting spoil material. Thanks to this timesaving, economical Kaytech geogrid, millions of rands were saved on this project.
