New breed of substrate to increase use of bonded and coated hardwoods in construction
A new type of substrate has been developed to enable hardwoods to respond better when glues are applied.
The new technology resulted in bond strength improvements of up to 300 per cent, suggesting the potential to use bonded and coated hardwoods for a much broader range of applications in construction.
The FWPA-managed research demonstrates how newly developed surface modification technology can significantly improve the strength and durability of systems that contain bonded and coated Australian hardwood products.
The investigation focused on the manufacture of hardwood bonding using adhesives made from the organic plastic ‘polyurethane’. It was conducted by a team from the CSIRO Manufacturing Business Unit, the University of Melbourne and Swinburne University. Bond strength improvements were observed when a thin layer of the polyurethane adhesion promoter ‘CSIRO Surf-BOND’ was applied to the wood surface prior to the bonding process.
Team Leader at CSIRO, Dr Xiaoqing Zhang said this new technology has the potential to inspire a significant increase of hardwood usage in the Australian building and construction sector.
The benefits became even more pronounced when bond performance was assessed after exposure to environmental conditions like high temperatures and extreme wetness and dryness. These results were validated in a range of scenarios, including laboratory-scale testing, pilot-scale trials, and, ultimately, a final demonstration during industrial trials at Australian Sustainable Hardwoods’ Heyfield manufacturing plant.
Researchers also observed, several clear coatings improved protection for surface-finished exterior hardwood products. Long term accelerated weathering assessments also showed certain high- and low-gloss clear coats survived up to 2,000 hours of Q-Sun or 4,000 hours of QUV testing, when used on various hardwood species.
Following this accelerated weathering, the coating layer retained high strength of adhesion to the hardwood surface, while the wood products also maintained their natural appearance.
“These results provide a promising solution for coated hardwoods in outdoor applications by overcoming surface damage upon solar exposure and alleviating the high cost of maintenance currently associated with exterior wood products,” Dr Zhang said.
“The outcomes of this research also create the potential for further innovation of architectural systems to be manufactured, surface finished and assembled offsite, ready for installation at the designated construction site.”
The team hopes with further R&D the technology can be extended to a broad range of Australian wood products, maximising benefits for the entire wood products sector.
“This will allow timber to be promoted and utilised as a sustainable and highly reliable engineering material in a much broader range of applications than has previously been possible,” concluded Dr Zhang.
The research findings can be found in full by clicking here.