Well-designed, integrated and visually stunning public buildings are increasingly showcasing the versatility of precast glass reinforced concrete (GRC) — a factory-made precast concrete renowned for its light weight and design flexibility.
GRC wall façade panels are manufactured using a cement-based composite material with alkali-resistant fibres that are dispersed throughout the product. Because the fibres add flexural, tensile and impact strength, they serve as reinforcement and the result is a strong yet lightweight architectural material.
The manufacturing process is different to that of conventionally reinforced precast – instead of the mix being poured into moulds, it is sprayed. The manufacture of larger elements has become a specialty process that is only taken on by a small number of precast manufacturers around the country.
When it comes to Australian-manufactured GRC, National Precast’s Chief Executive Officer, Sarah Bachmann, speaks proudly of her organisation’s members that specialise in precast GRC.
While the manufacture of smaller GRC elements – such as planters and bench tops – is more common, she says the manufacture of high quality GRC wall façades is left to only a few of the organisation’s members.
“While Sydney’s Concrete by Design, Adelaide’s Asurco Contracting and Brisbane’s Precast Concrete Products can easily all handle smaller elements, only Asurco and Precast Concrete Products have taken on the task of manufacturing wall façade elements around the country,” she explains.
“We’ve heard of some recent projects awarding precast GRC supply to foreign suppliers, but the quality just isn’t the same.”
Architectural designs can occasionally demand intricate detail – detail that hinges on the use of precast GRC.
“The results that GRC can achieve when the precaster works closely with the designer are nothing short of stunning. These projects are winning awards,” Ms. Bachmann says.
The award-winning Wynyard Walk
Having recently won the State Award for Infrastructure Projects at the Concrete Institute of Australia’s Awards for Excellence, the new Wynyard Walk is an example of precast GRC in Australian infrastructure. This major pedestrian walkway now connects Sydney’s Wynyard Station to the bustling Barangaroo waterfront precinct and the CBD.
Asurco supplied and installed the GRC panels, which feature on the walls and ceiling of the tunnel. The precaster’s manufacturing process involved framing, mould-making, manufacturing, installing and coating the elements. Asurco’s owner, Des Pawelski, says that although the curvature of the tunnel posed challenges, the end result is magnificent.
“The GRC panels feature beautiful stainless-steel strips and are coated in anti-graffiti paint,” he explains.
“The panels twist and curve with the bends of the tunnel. It was a really challenging job but the architects did a brilliant job and the end result is stunning.”
Barangaroo’s waterfront attracts up to 33,000 visitors and occupies approximately 23,000 office workers daily. The new 180-metre walkway allows pedestrians to travel from the station to the waterfront in just six minutes, making it a vital part of the NSW Government’s commitment to meet transport demands in Sydney.
Geelong’s landmark library
Another recent example of GRC making its mark is the nine-storey Geelong Library and Heritage Centre. This $45.5 million project is being hailed a landmark building and is a spectacular addition to the surrounding cultural and architectural landscape. Continuing Victoria’s tradition of great libraries, it boasts a unique dome design and precast GRC cladding.
Asurco manufactured 332 GRC panels for the project and meticulously transported them interstate to Geelong, Victoria. The panels are asymmetrical and geometrically pentagonal or hexagonal and were manufactured complete with a secondary steel sub frame and then bolted to the primary structure to create the domed façade.
“While the GRC is lightweight, it retains the enduring qualities of concrete,” Mr. Pawelski says.
“It’s so flexible in its design and finish, which means it’s suited to varying architectural styles.”
Newcastle Court House’s new era of justice
Designed to complement its surrounding urban environment, the Newcastle Court House is a redevelopment that similarly showcases the versatility of precast GRC in infrastructure projects. Newcastle’s justice system entered a new era when the innovative structure opened and the scope for custom-made intricate patterns using GRC was highlighted.
Asurco manufactured 70 panels that made up the decorative screening façade. A master mould was fabricated from plywood and a rubber mould was then made, into which GRC was sprayed.
“For the Newcastle Court House project, both sides of the panels had to be of particular high quality as each side of the panel is visible from the both the inside and outside of the building,” Mr. Pawelski says.
The new Newcastle Court House was shortlisted for the prestigious 2016 NSW Architecture Awards in the category of Public Buildings. The project was recognised for its state-of-the-art design – a design that hinged on the use of precast GRC.
“Hopefully this project gets more architects thinking about GRC as a viable option when they want to achieve complex shapes,” Mr. Pawelski adds.
Building a temple with GRC
With a majestic and otherworldly exterior, the Wat Dhammadharo Thai Buddhist Temple in Canberra exhibits impressive precast GRC elements. The temple features the only pagoda in the southern hemisphere set among traditional Thai architecture.
The GRC elements of the temple were manufactured over a nine-month timeframe, with the majority of GRC moulds designed by Asurco and some intricate details moulded in Thailand. The glass fibres in the GRC are typically sufficient to reinforce the concrete, but because of the ambitious design the GRC was supported, in some cases, by lightweight and heavier steel frames.
“This was a very satisfying job in the factory because we made something from nothing and the end result is quite beautiful,” Mr. Pawelski says.
“The gold coating for the elements is a mineral paint, which results in a durable, colourfast and sustainable protective finish that promises low maintenance and longevity.”
A remarkable offering
Ms. Bachmann believes that GRC can be a remarkable architectural addition to any infrastructure project.
“The applications don’t just stop at smaller elements and building facades,” she says.
“It’s frequently used in the civil space too, with GRC being specified for noise walls. The intricacy of design combined with the inherent benefits of the product make it a long lasting, aesthetically pleasing solution that is producing amazing results.”