Page 38 - InnoRenew CoE International Conference 2021, Healthy and Sustainable Renovation with Renewable Materials
P. 38
eep Behaviour of Densified Wood
Lei Han 1, Andreja Kutnar 2,3, Dick Sandberg 4
1. InnoRenew CoE, Livade 6, SI-6310 Izola, lei.han7@innorenew.eu
2. InnoRenew CoE, Livade 6, SI-6310 Izola, andreja.kutnar@innorenew.eu
3. University of Primorska, Titov trg 4, SI-6000 Koper, andreja.kutnar@upr.si
4. Luleå University of Technology, Forskargatan 1 SE-931 87 SKELLEFTEÅ, dick.sandberg@ltu.se
Due to the reproducibility, good workability, suitable mechanical properties, and attractive aesthetic
appearance, timber is widely used in the building industry. Among those properties, mechanical
properties are important for the useability of timber in construction applications. It is well known that
there is a positive relationship between wood density and its mechanical properties. That means the
thermo-hydro-mechanical (THM) densification, i.e. transverse compression of the wood cells only by
using additional temperature, moisture and mechanical action to increase its density without structural
fracturing is a practicable method to increase the performance of low-density species and thereby
improve its mechanical properties. The previous studies on wood densification mainly focused on the
influence of process parameters on wood physical and mechanical properties and how to use post-
treatment to reduce the set recovery. This study is in the field of increasing the use of densified timber in
construction applications and thereby strengthen the competitiveness of wood as a construction material.
In construction, however, densified timber normally needs to be exposed to long-term loading which may
lead to creep deformation and reduction of load-bearing capacity. There is an obvious risk of reduced
serviceability and safety of constructions containing densified wood. Studies of creep characteristics
of densified wood are rare, and therefore the purpose of this study was to fill the gap in knowledge if
the field of densified under bending load. Scots pine specimens subjected to THM densification, THM
densification with a post-heat treatment, and THM densification combined with phenol resin impregnation
were loaded under 3-point bending under the 35% of maximum stress level at 20℃ and 65% RH. Results
from these tests will be presented.
Keywords: heat-treatment, resin impregnation, Scots pine
Acknowledgement
The European Commission for funding the InnoRenew project (grant agreement #739574) under the
Horizon2020 Widespread-2-Teaming program and the Republic of Slovenia (investment funding from
the Republic of Slovenia and the European Regional Development Fund) are greatly acknowledged.
INNORENEW COE INTERNATIONAL CONFERENCE 2021
38
Lei Han 1, Andreja Kutnar 2,3, Dick Sandberg 4
1. InnoRenew CoE, Livade 6, SI-6310 Izola, lei.han7@innorenew.eu
2. InnoRenew CoE, Livade 6, SI-6310 Izola, andreja.kutnar@innorenew.eu
3. University of Primorska, Titov trg 4, SI-6000 Koper, andreja.kutnar@upr.si
4. Luleå University of Technology, Forskargatan 1 SE-931 87 SKELLEFTEÅ, dick.sandberg@ltu.se
Due to the reproducibility, good workability, suitable mechanical properties, and attractive aesthetic
appearance, timber is widely used in the building industry. Among those properties, mechanical
properties are important for the useability of timber in construction applications. It is well known that
there is a positive relationship between wood density and its mechanical properties. That means the
thermo-hydro-mechanical (THM) densification, i.e. transverse compression of the wood cells only by
using additional temperature, moisture and mechanical action to increase its density without structural
fracturing is a practicable method to increase the performance of low-density species and thereby
improve its mechanical properties. The previous studies on wood densification mainly focused on the
influence of process parameters on wood physical and mechanical properties and how to use post-
treatment to reduce the set recovery. This study is in the field of increasing the use of densified timber in
construction applications and thereby strengthen the competitiveness of wood as a construction material.
In construction, however, densified timber normally needs to be exposed to long-term loading which may
lead to creep deformation and reduction of load-bearing capacity. There is an obvious risk of reduced
serviceability and safety of constructions containing densified wood. Studies of creep characteristics
of densified wood are rare, and therefore the purpose of this study was to fill the gap in knowledge if
the field of densified under bending load. Scots pine specimens subjected to THM densification, THM
densification with a post-heat treatment, and THM densification combined with phenol resin impregnation
were loaded under 3-point bending under the 35% of maximum stress level at 20℃ and 65% RH. Results
from these tests will be presented.
Keywords: heat-treatment, resin impregnation, Scots pine
Acknowledgement
The European Commission for funding the InnoRenew project (grant agreement #739574) under the
Horizon2020 Widespread-2-Teaming program and the Republic of Slovenia (investment funding from
the Republic of Slovenia and the European Regional Development Fund) are greatly acknowledged.
INNORENEW COE INTERNATIONAL CONFERENCE 2021
38
