Investigation of an innovative preservative treatment of green timber using compression

ABSTRACT

Impregnation of an appropriate chemical compound in wood is a common technique to improve durability, fire retardant properties, strength and dimensional stability, increase hardness and UV resistance. This study investigated a compression treatment followed by dipping in Alkaline Copper Quaternary solution (ACQ) as an alternative treatment method of green (unseasoned) southern pine timber. The effects of the compression parameters on ACQ uptake were investigated. The results showed that ACQ uptake increased disproportionally from 24 to 225 L/m³ with the increase of the compression ratio from 10% to 50%. ACQ uptake increased gradually from 65 to 120 L/m³ at a compression speed between 5 and 40 mm/min and dropped to 46 L/m³ for a compression speed of 50 mm/min. Radial compression resulted in a lower uptake than 45° and tangential compression. The penetration depth of Cu was satisfactory for most of the sapwood specimens for a compression ratio greater than 30%. For the heartwood/sapwood mixed specimens, 100% Cu penetration was achieved in the sapwood portion however the heartwood portion remained unpenetrated. The compression treatment could potentially reduce the treated timber cost by reducing drying cost and processing time while achieving a satisfactory performance as specified by the Australian standard.

KEYWORDS:

• Timber treatment
• Alkaline Copper Quaternary (ACQ)
• compression treatment
• preservative
• penetration
• retention

Acknowledgments

Bill Leggate from Koppers Performance Chemicals is acknowledged for supplying ACQ solution and reviewing the manuscript. The author would like to thank Dr Maryam Shirmohammadi, Adam Faircloth, Rica Minett for assistance with the specimen preparation and experimental testing and Dr Adam Redman, Tony Dakin, Bill Leggate, Dr Henri Bailleres for suggestions. The author thanks Ian Last and Darron Moates from HQPlantations for supplying the green logs and Eric Littee and Daniel Field for collecting the logs. The author acknowledges the Agri-Science Queensland Innovation Opportunity fund to conduct this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Horticulture and Forestry Science Innovation Grant [project number HF10913].