The future of the construction industry could be changed completely if the concept of demountability is driven at larger scale structures, says University of New South Wales (UNSW) School of Civil and Environmental Engineering professor, Brian Uy.
And the material to lead that change would be steel, one of the common building materials in Australia.
Demountable structures are those which can be easily disassembled at the end of a building’s life, with traditional structures limited to short-term use such as travelling shows, carnival structures and school classrooms. However, Professor Uy argues that large scale demountable buildings with longer lifespans is a feasible proposition – one that would take the steel used in existing buildings for new projects, thereby avoiding the need to smelt new steel.
Steel is at present one of the world’s most recycled products, with BlueScope noting that about 65 per cent of all steel in Australia goes back into the making of new steel.
But Professor Uy points out that recycling the product while reducing steel waste “consumes only marginally less energy than producing steel from scratch”.
“Steel is a major cost for the construction industry and its production also heavily impacts the environment,” he says.
“The benefit of using demountable steel structures is that waste can be significantly minimised both during construction and at the end of a structure’s life. Structural steel also has the potential to harbour some residual value which could encourage reuse.
“Implementing re-used steel could be a game changer for the construction industry by reducing the environmental and cost impacts of using steel in new buildings.”
Structural steel is particularly suitable for these applications as it lends itself to bolted construction methods, which are already commonplace in commercial structural steel buildings. The development of appropriate components and connections are now underway, with UNSW currently carrying out research on bolted connections.
One of the projects Professor Uy is involved in is an Australian Research Council (ARC) Discovery project, which investigates the behaviour of ‘blind bolts’ that connect structural steel beams to concrete slabs in both new construction and for rehabilitating existing steel infrastructure.
The use of these blind bolts in new construction will enable buildings involving multiple dissimilar materials to be connected, while facilitating the deconstruction of steel structures.
Notwithstanding the feasibility of large demountable steel structures, whether there is a market for used steel is another question altogether. Professor Uy, however, is confident that architects and builders will play a role in driving the demand of reused steel.
“There could be some design interest in bespoke steel products of previous historical eras that could be incorporated in the modern design process. For example, cast iron columns and melted steel constructions have seen resurgence in contemporary architecture,” he explains.
“Steel suppliers probably have the greatest role to play. They could purchase steel from projects which are being demolished, then stock and resell the reused steel for new constructions.”
In this market, all steel is traceable through unique barcodes, which would help to track the re-use of steel structure supports. With access to a list of available materials, architects could base their structures on, or incorporate steel from existing structures from the beginning of the design process.
For this market and process to be viable, Professor Uy notes that minor adjustments would have to be made to product and building regulations to allow for typical connections in large applications. On top of that, existing and future codes and standards would need to recognise, characterise and assess the reliability of the material being supplied from the reused stock.
Already, countries like Malaysia are taking steps toward this model, with the Institution of Engineers Malaysia and Institution of Structural Engineers, Malaysian Division influential in promoting Cradle to Cradle concepts for infrastructure in Malaysia. In the UK, the Sustainable Construction Panel of the Institution of Structural Engineers recently submitted a white paper to promote reuse in BREEAM, the UK green building scheme.
Although the Australian industry does not yet actively encourage the re-use of steel, Professor Uy says the government’s Asset Recycling Fund could potentially provide long-term opportunities for these larger-scale cradle to cradle concepts.