Construction World April 2018

GEOTECHNICAL

ALTERNATIVE to earth retention system Fibertex geosynthetic sand containers (GSC- Bags) have been successfully used by WBB Builders, as an alternative to conventional earth retention systems, at recently completed landscaping projects in Umhlanga Ridge, KwaZulu-Natal. “Lateral earth retention solutions, incorporating GSC bags, are highly recommended by builders and landscapers, in projects where land space is limited and a green facing is required. WBB Builders in Durban selected Fibertex GSC bags for these projects, as a lightweight, durable and cost effective substitute for traditional lateral earth retention systems. In cases where the height of a wall and the face angle of a bag wall system are increased, additional reinforcing components, such as soil reinforcing geogrids, are added to the structure, in accordance with the engineer’s design requirements.

Fibertex Naue Secugrid 40/40Q6 soil reinforcing biaxial geogrids – with high modulus extruded monolithic bars and welded junctions – are used to minimise soil deformation under tensile loads over the lifetime of the structure. The Fibertex team has given particular attention to critical factors in the development of this protection system, including abrasion and UV resistance, to minimise damage during installation and exposure over long periods of time. Hydraulic qualities of the nonwoven Fibertex geotextile these GSC bags are made from are critical to ensure a high enough flow rate through the geo-textile, while still being able to efficiently retain and filter the finer fill material. Geotechnical and civil engineers recommend consideration of the following factors when planning and designing a landscaping structure, using Fibertex GSC bags as the component to a lateral earth retention system :In-situ soil conditions • Wall/slope height and face angle • Surcharge on top of the wall and slope • Type of vegetation above the wall and on the slope • Fill drainage systems must be incorporated into the design to prevent excessive build-up of pore water pressure in the fill material. • As in the case of other designed concrete block walls, these structures should also be designed by and constructed under the close supervision of a structural or geotechnical engineer. All variations of Fibertex FiberRock GSC bags are manufactured at the company’s plant in Kwazulu-Natal, according to the consistent quality control policy of the Fibertex group, which is held to stringent international standards. 

F ibertex FiberRock 30S GSC bags are made from a strong and highly porous fabric, which is mechanically needle-punched together. By filling these bags with a free draining medium (in this case 40 - 70 kg sand), a durable retaining structure can be built, whilst allowing the free passage of water through the structure. “Fibertex nonwoven geotextiles, which are manufactured from highly UV stabilised virgin Polypropylene (PP) or recycled Polyester (R-PET) fibres, are gaining popularity in landscaping and building installations. These GSC-bags are an attractive and efficient protection for slopes and also aid in erosion control,” explains Gerard Dirks, Technical Manager, Fibertex SA. “Fibertex UV stabilised virgin PP geotextiles are the only nonwoven geotextiles produced in Africa with certification for durability of over 100 years, in accordance with the latest EN standards.

Newly installed GSC bags. After being securely placed, the front row of bags can be pierced and planted with sods, to the landscape architect’s specifications.

GSC Bag design to break a steep slope into smaller, more manageable terraces.

Fibertex 30S GSC bags are a lightweight, durable and cost efficient solution to landscaping designs that require lateral earth retention systems in walls and slopes.

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CONSTRUCTION WORLD APRIL 2018