Thermo-Hydro-Mechanical Treatment of Australian Sawlog and Pulplog Hardwood Resources
Kotlarewski, N and Lee, M and Schwartzkopf, M and Pecnik, J and Mikuljan, M, Thermo-Hydro-Mechanical Treatment of Australian Sawlog and Pulplog Hardwood Resources, InnoRenew CoE International Conference 2020 Book of Abstracts, 09 June, Izola, Slovenia, pp. 16. ISSN 2784-6679 (2020) [Conference Extract]
Australian sawn-board product is regulated by timber’s physical and mechanical properties
to ensure safe operating performances in context specific applications. Contemporary and
emerging timber resources, however, are lacking the traditional properties of commercially
sawn products, namely density. One technique used to improve timber properties is densification
through thermo-hydro-mechanical (THM) treatments (Rautkari et al., 2010; Sandberg et al.,
2013; 2007). The objective of this study was to assess the change in timber properties of several
Australian wood species densified using a THM treatment to identify if these modified species
could be utilised in regulated building applications. Three hardwood species from different
forest management schemes were tested in this study: Eucalptus obliqua, E. nitens, and E. globulus.
E. obliqua was sourced from regrowth sawlog (60 year-old), E. nitens from plantation sawlog (26
year-old) and plantation pulplog (16 year-old) and E. globulus from plantation pulplog (26 yearold).
Australian Standard (AS) 3959:2018—Construction of buildings in bushfire-prone areas—
states E. obliqua and E. globulus are suitable for general construction with a density ≥750kg/
m3 and E. nitens is suitable for window and door joinery with a density ≥650kg/m3. Air-dry
densities measured from each species, according to their respective forest management scheme,
suggest sawn-board products from these resources are lower in density than required for use
in building construction in bushfire prone areas; E. obliqua ~595 kg/m3, E. nitens (sawlog) ~560
kg/m3, E. nitens ~525 kg/m3 and E. globulus ~520 kg/m3. By using THM treatment, samples were
densified to 67% and 53% of their original thickness (15mm) to demonstrate modified sawnboard
can meet AS for use in construction and joinery; E. obliqua ~875 kg/m3 and ~980 kg/m3,
E. nitens (sawlog) ~775 kg/m3 and ~1015 kg/m3, E. nitens ~680 kg/m3 and ~940 kg/m3 and E.
globulus ~775 kg/m3 and ~870 kg/m3 at 67% and 53%, respectively.