ENVIRONMENTAL ENGINEERING
Gabions build a foundation for SMME development Purpose-designed to shape environmentally engineered structures, gabion designers can use a range of wire or welded mesh options to form them. Being labour-intensive, their construction also presents major opportunities to create community employment, and develop specialist SMME subcontractors, says Louis Cheyne, managing director of Gabion Baskets. By Alastair Currie
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hen we star ted the business some 15 years ago, our core focus was on fabricating gabion systems sourced from locally manufactured Class A galvanised and PVC-coated, double-twisted hexagonal woven mesh wire systems – the latter designed for more corrosive environments,” explains Cheyne. “We then subsequently branched out into welded mesh products as an allied offering for the environmental engineering, architectural and landscape markets,” Cheyne continues, adding that this ser vice includes design recommendations, costing and project management, as well as integrated solutions such as geotextiles and erosion control blankets. Another key development is the provision of SMME contactor business training and installation ser vices for both public and private sector clients.
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IMIESA February 2022
A boundary wall section constructed using welded mesh and filled with river stones for maximum aesthetic effect
Via its in-house programmes, Gabion Baskets employs full-time instructors that travel to client sites to conduct installation training – locally and into Southern Africa. In terms of the latter, various projects have recently been completed in countries that include Zambia. Externally, Gabion Baskets refers clients to CETA-accredited FET colleges that include Tjeka. “Contractors are increasingly approaching us for project design recommendations when it comes to community-based contracts that incorporate gabions. We’re also receiving an unprecedented number of enquires from SMMEs who need advice on how to enter the gabion construction market,” says Cheyne. “Since our Johannesburg factory borders Alexandra township, we’re especially aware of the unemployment crisis within previously disadvantaged communities. Where the skills don’t exist, we feel an obligation to help aid South Africa’s economic reconstruction and recovery plan through our own or externally facilitated business and skills development programmes. In recent years, this has enabled us to support a growing network of industryaccredited SMMEs,” Cheyne continues.
Quality control Building the right foundation is essential for SMMEs to grow and flourish. Poor design is the starting point for a potential gabion failure. However, even the best design can fail if the correct bracing, lacing and packing techniques are not applied. The classic gabion contains around 35% voids and is intentionally meant to provide a greater or lesser degree of permeability. Understanding and executing the design brief is therefore essential. Adherence to material qualities is equally important. SANS 1580:2010 sets
the standard locally and globally for the correct manufacturing specification for hexagonal steel wire mesh gabions and revet mattresses. In turn, SANS 1200 DK:1996 governs the correct installation techniques for gabion systems. “Generally, when you buy mesh from a hardware store, it’s commercially galvanised. In other words, it doesn’t meet the SANS 1580: 2010 standard for environmentally engineered applications and will fail prematurely when placed in a corrosive environment,” says Cheyne.
Specifications are application specific The correct specification will always be application specific and in accordance with the anticipated life expectancy. In a marine or river environment, for example, a more corrosionresistant PVC coated wire is recommended. The alternative is a Galfan with PVC-coated Class A galvanised wire. Where gabion systems do fail – either through negligence or uncontrolled factors like extreme weather or vehicle impacts – the repair solutions are often straightforward, although this doesn’t negate the added cost. “Often the damage can easily be fixed with some extra rock and mesh panels reattached onto older baskets. In some situations, the structural design can also be modified to serve or counter new problems encountered, like recurring floods spurred on by climate change,” adds Cheyne. “The magic of gabions is their design and build flexibility, and it’s not unusual for these systems to last 50 years or more with minimal maintenance. That of course depends on best-in-class installation and optimal material selection,” Cheyne concludes.
