An innovative precast concrete building system that is widely used in Europe, is now available in Australia and has already helped engineering and construction firms to meet deadlines and overcome logistical changes.
When engineering giant Laing O’Rourke took on a project with the University of Sydney to redevelop its Engineering Technology Precinct in 2019, one of the key considerations was to minimise disruption to the existing premises, while delivering a systematic refurbishment.
The precinct renewal includes the addition of a new Electrical Engineering building and will consist of approximately 11,000 m 2 of new or shelled space and 6000 m 2 of refurbished facilities. It also involves a Building Council of Australia upgrade of the existing Southern J03 building, and the addition of a new 10-storey wing to the building’s North.
Having used Double Wall on projects throughout Europe, Laing O’Rourke Project Lead Joe Thompson was familiar with the many advantages the product presents.
As Double Wall significantly reduces materials handling on site, such as scaffold and reinforcement, it liberates space to improve site logistics. It also reduces the critical time spent on the construction of vertical elements and avoids the need for scaffold. For Thompson, these were crucial considerations in ensuring the disruption was minimal.
“The Austral Precast Double Wall system allowed us to reduce the noise and activity associated with traditional construction of vertical elements, which created a positive outcome for the build and the wider university community,” he said.
“Working on a 10-storey building, with a basement, on a tight footprint with a challenging program meant that conventional formwork methodology was not viable for this project.”
The unique product is a structural system consisting of a pair of precast reinforced concrete shells connected by lattice reinforcement trusses. Steel reinforcement, edge forms and built-in components can also be factory assembled and transported to the construction site as part of the system.
Once on site, the edge forms and reinforcement connections are completed and the hollow cavity is filled with premixed concrete to create a solid structure, tying the Double Wall panels to adjacent walls and floors.
The product offers many advantages. Most importantly it helps achieve incredible on-site time and cost savings because the entire structure, walls, floors and shafts are cast simultaneously.
“The Double Wall system provided all the benefits of off-site factory production, freeing valuable space around the perimeter of the build,” Thompson said.
“The reduced weight of the panels could also be installed with smaller capacity cranes, which contributed further to space and cost savings.
“By using Austral Precast Double Wall, we have achieved savings in installation costs and time, providing certainty to our ability to complete on or ahead of program, and minimising disturbance to students and staff.”
Austral use Quality Assurance Personnel to assess the manufacture of panels in the factory. This presents another product advantage.
Traceable photos and documentation provided to certifying engineers means there is reduced inspection required from contracted engineers, further reducing downtime and speeding up the schedule for the builder. And, unlike traditional walls that can take days to construct, the Double Wall system can be installed, poured and completed in one day.
Each Double Wall is custom designed, and the overall wall thickness can vary between 200 mm to 400 mm, depending on the structure and applied loads. Installation efficiency is achieved due to the relatively large and light-weight panel, as well as the enhanced jointing method, which removes the need for caulking, welding and formwork. This makes it ideal for cores, shear walls and basements.
The Astina Suites Project in Penrith, NSW also used the Austral Precast Double Wall to bring the eight-storey building, with 58 luxury apartments and three office suites, to completion in record time. The project began construction in October last year and is an extension of the existing serviced apartments that have been operating in the area for more than 20 years.
With the aim of delivering a luxury hospitality and hotel precinct to Penrith City, the suites will be accompanied by a ground floor wine bar, café, office, valet parking, private garden, rooftop pool, bar, gym and function centre.
The system was integral in achieving a quick turn-around, as the walls, floors and shafts are cast simultaneously, with little to no downtime.
“Much of the appeal of the Double Wall system stemmed from our need to streamline our construction process by minimising downtime,” said Thomas Schrumpf, Astina Construction Manager.
“Being an eight-level building with an additional two-storey basement, this project is a big task with a very tight deadline.
“This was our first time using the Double Wall system and the results truly speak for themselves. The system is significantly faster than traditional blocklaying techniques, and we are set to complete the project ahead of schedule.”
The double precast walls are interesting. But instead of filling the gap between with heavy concrete, would it be possible, feasible to fill it with expanding insulation. This would be lighter, provide inaulation and reduce building costs. Sorry, I’m not an engineer. Just a thought. Ralph