The traditional role of gabions in constructing engineered systems, like mass gravity retaining walls, is now increasingly crossing over into parallel applications outside the mainstream civils industry that include landscaping and architecture. Alastair Currie (IMIESA magazine), speaks to Louis Cheyne, managing director of Gabion Baskets, about current trends.

One of the key drivers locally and internationally is the ongoing refinement of square welded mesh panels, which provide a flat finish particularly well suited for wall cladding and feature walls,” explains Cheyne. “The natural appeal of the rock fill used to form gabions has also been a key influencer for landscapers and architects, along with durability and aesthetic benefits.”

Conventional hexagonal double-twisted woven mesh gabion systems can achieve the same effect, but their performance characteristics are different. Welded mesh is intentionally rigid, whereas woven mesh is designed to flex. The latter is particularly important for applications like submerged riverine retaining walls, where welded mesh would fail. However, both woven and welded mesh can be specified for land-based mass gravity retaining walls, but choosing the hexagonal woven mesh option is the logical choice given the lower cost at scale, unless there’s a specific design requirement.

DIMENSIONAL WIRE TOLERANCES

Therefore, the starting point for choosing a woven or welded option is dependent on the application and thereafter the ultimate result required, which comes down to the accepted dimensional wire stretch tolerances.

Welded mesh panels – given their intentional rigidity – must comply to industry standard tolerances in a range from 0,5 mm to 0,10 mm. However, with woven mesh the acceptable variance is greater at a threshold of around 5%. The reason for this is the need to make provision for the inherent nominal expansion and contraction of woven mesh systems when bracing and tensioning baskets during installation.

“In our view, however, 5% is too high, and our woven mesh systems and design recommendations make provision for a maximum 2,5% variability,” Cheyne continues. “This of course is dependent on correct installation and rock filling techniques. When perfectly executed, the geometry all comes together, whether it’s a gabion staircase, a weir or a retaining wall. For predominately non-engineered structures, welded mesh takes this a step further.”

WELDED MESH DIVERSIFICATION

Historically, Gabion Baskets first entered the welded mesh market with a 75 mm x 75 mm panel product composed of 3 mm diameter Class A galvanised wire. This was followed by 50 mm x 100 mm, and 50 mm x 50 mm panels to meet growing demand. In all cases, products can now be specified either with 3 mm or 4 mm diameter wire within a tensile strength range of 350 to 550 MPa.

“A thicker wire specification provides far greater rigidity and lends itself to the creation of new product lines. For, example, our new gabion barrier systems – employed for tasks like flood emergency mitigation and military protection – use a 75 x 75 mm panel with a 4 mm wire. Lined with a geotextile basket sock, these barriers can be filled with any material, including sand, and are quick to deploy thanks to their prefabricated modular concertina design. Since they fold flat into a compact space, they are also easier to transport and store,” Cheyne explains.

Another key advantage is that welded mesh gabion wire panels may be rigid in term of tolerance dimensions, but that doesn’t stop them from flowing with the curves. “Rounded shapes and corners are a major trend globally, and we’re adding our own unique interpretation locally through an upgrade in our manufacturing lines,” says Cheyne.

GROWING ENTRY POINTS

Either way, whether it’s for a commercial, industrial or residential project, Cheyne says the rising volume of welded mesh enquiries from built environment professionals, as well as private clients, is remarkable. These include enquiries for garden terraces, boundary walls, freestanding walls, barrier protection, building cladding, as well as commercial signage. The latter is one of Gabion Baskets’ new product lines.

“Climate change impacts are a constant reminder that our fragile ecosystems are under increasing threat and need to be countered with greener initiatives. Gabions are a natural response from an environmentally engineered perspective, as well as from a sustainability standpoint, plus there’s tremendous comfort in being interconnected with natural stone – whether it’s ultimately a welded or woven solution,” adds Cheyne.

“Full engineering design and on-site practical installation training is offered to assist in using these product lines,” Cheyne concludes.