New surface treatment to boost hardwood building components’ spanning capability
A new mystery surface treatment developed by the CSIRO is set to enhance the viability and desirability of hardwood components in construction, by improving bond strength when adhesives and coatings are applied.
In research funded by FWPA, the patented surface treatment significantly improves strength when bonding hardwoods together using polyurethane adhesives, and increases the bonding capacity of timber and clear coatings.
FWPA Research and Development Manager Chris Lafferty, described the results as exciting.
“In practice, this treatment will deliver added consistency, stability and reliability of hardwood timber products, particularly in situations where the timber is exposed to changing conditions such as seasonal variations and in species that are notoriously difficult to laminate,” he said.
Explaining some of the practical advantages to industry, Alex Edwards, Associate at engineering firm ARUP and Steering Committee member said: “With hardwood beams generally being stronger than their softwood counterparts, being able to reduce their size and increase their spanning capabilities through stronger adhesive bonding would certainly be of great benefit.
“Additionally, with the natural oil found in timber causing coatings to lift off over time, this treatment could significantly reduce the need for regular reapplication. Reducing the need to re-apply coatings would further increase the desirability of hardwood as a building material of choice.”
The CSIRO patented treatment is applied to the surface of the timber before the application of adhesives or coatings. The team’s rigorous testing, including up to 4,300 hours of exposure in an accelerated weathering laboratory, has shown adhesives form a deeper and stronger bond with the timber, resulting in improved strength, while coatings become substantially more durable, enabling them to withstand conditions such as UV exposure.
During the testing, the bond strength of Victorian Ash, Blackbutt, Spotted Gum, Blue Gum, and Tallow wood showed an improvement in bond strength of up to 100 percent following treatment.
The research team declined to reveal what the treatment is made of, and it is too early to say what it would cost in a commercial setting.
Vince Hurley, Managing Director at Australian Sustainable Hardwoods and Steering Committee member said: “The project has resulted in industry ready technology that will substantially enable the manufacture and application of advanced hardwood building components. Putting together a multi organisation research team, a multi-industry steering committee, and having clear objectives overseen by a mentor is the key to this success.”
The multi-disciplinary steering committee behind the project is being led by mentor Professor Voytek Gutowski, a CSIRO Fellow with a strong and extensive background in research to application.
Professor Gutowski is being supported by researchers from diverse backgrounds. Xiaoqing Zhang and Sheng Li of CSIRO Manufacturing are experts in bonding and coating technology and accelerated weathering trials and assessment. Professor Barbara Ozarska and Benoit Belleville of the University of Melbourne are highly experienced in commercial scale trials and testing of timber bonds. Meanwhile, Professor Blair Keys and Matthew Gutowski of Swinburne University have expertise in building component and manufacturing process design.
The steering committee also comprises expert industry representatives from diverse backgrounds including engineering, architecture and manufacturing. This includes Chairman Vince Hurley of Australian Sustainable Hardwoods, Ken McBryde of Hassell and Sydney Architecture Studio, Alex Edwards of ARUP and Chris Lafferty of FWPA. Inaugural Chairman was Douglas Head of Australian Solar Dryers (ASD), who was later replaced by Malcolm Johnston of Hurford Hardwoods following the sale of ASD to Hurfords.
The final stage in the three-phase project will include further timber bond strength trials using a range of species to establish the criteria for optimum performance of the treatment on each, and the refining and development of recommendations around the methodology and equipment necessary for successful industrial application.
Component design will also be an important consideration for the team going forward, to ensure hardwood products are built in a way that will achieve optimum performance when using the treatment.