The current economic climate, the call for more energy-efficient buildings and new legislation have forced companies to re-investigate the application of traditional construction materials such as steel, concrete and timber. Composites, particularly glass-reinforced plastic (GRP), have gradually made inroads as an alternative and equal construction material.
Originally developed in 1938 for use in insulation, GRP is extremely durable, offering a combination of properties seldom found in other materials. It has excellent impact strength, low weight and is dimensionally stable. GRP can also withstand extreme weather conditions and is energy-efficient.
It was introduced into the International Building Code (IBC) in 2009 and has already been used with great success in projects such as the new 3 050m² Masscash Holdings Trading Warehouse, contracted to Scheltema. The trading warehouse with an apex height of 12m gave the client flexibility with its racking layout and allowed for bulk storage of up to 6m. It was one of the first large-scale projects in the Western Cape to make use of non-fragile GRP sheeting known as Modek GRP Walk-on.
Internationally the Amex Stadium, British Oval Cricket Ground, Emirates Stadium, Thomond Park, Twickenham Stadium and Dubai International Airport have all made use of GRP cladding, roof lights and canopies. It is also popular in countries such as United Arab Emirates (UAE), where it is used to form bridge decks and walkways.
GRP panels make excellent cladding for other structural materials in high-rise buildings. In this, the ease of fabricating large panels in a GRP, as well as the versatility in terms of colour, shape and texture, offer a distinct advantage.
“In the long run, plastic cladding offers an attractive appearance that is easy to clean,” says Christo Pienaar, marketing director of Modek and Ampa Plastics. Both companies supply GRP sheeting to the construction industry. “It is strong and can withstand a great deal of stress, as well as extreme temperatures, marine conditions and strong winds. GRP is also excellent for use in buildings where chemicals are used.”
Modek produces opaque GRP sheets using high-grade isophthallic chemically-resistant polyester resin for the industrial industry, including battery-manufacturing plants, refineries, poultry farms and galvanising works. The company also supplied over 7 400m² of isophthalic sheets to the Skorpion zinc mine in Namibia to replace their polyethylene cladding that corroded due to chemical degradation and is currently working on a similar project with Namdeb.
Pienaar says some original GRP roof sheets from the 1940s are still in use today. “We manufacture our sheets with a protective layer to avoid UV damage and that increases the longevity.” Other benefits include its high thermal resistance, moisture- and mildew-resistance, mechanical strength and the reduction of installation time.
GRPs’ installation time is fast and effective because it is easy to cut, drill, fit and carry on site. Polycarbonate is also becoming more popular. The innovative Lansdowne Road Stadium in Dublin used polycarbonate to coat the walls and to create a light, translucent enclosure reflecting the colours of the sky. Transparent roofing was also used, which tilts over the south side of the building to allow light to reach the playing field.
Locally, Rock Construction is making use of Modek polycarbonate sheeting to re-clad the Pavilion Shopping Centre in KwaZulu-Natal. “Specifiers in South Africa are slow to make use of plastic construction materials,” Pienaar says. “This will change as construction companies and architects become more aware of the benefits. We are seeing a significant increase in the demand of this product.” He concludes with a prediction that GRP products are going to be as commonly used as steel and bricks soon.
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