Page 55 - Kutnar, Andreja, et al., eds., 2015. Proceedings of the 1st COST Action FP1307 International Conference - Life Cycle Assessment, EPDs, and modified wood. University of Primorska Press, Koper.

racterisation
of
interactions
between
thermally
modified
wood
and

water

Miha
Humar1,
Davor
Kržišnik2,
Boštjan
Lesar3,
Nejc
Thaler4,
Mojca
Žlahtič5

1
University
of
Ljubljana,
Biotechnical
Faculty,
Departement
of
Wood
Science
and

Technology,
Ljubljana,
Slovenia,
miha.humar@bf.uni-­‐lj.si

2
University
of
Ljubljana,
Biotechnical
Faculty,
Departement
of
Wood
Science
and

Technology,
Ljubljana,
Slovenia,
davor.krzisnik@bf.uni-­‐lj.si

3
University
of
Ljubljana,
Biotechnical
Faculty,
Departement
of
Wood
Science
and

Technology,
Ljubljana,
Slovenia,
bostjan.lesar@bf.uni-­‐lj.si

4
University
of
Ljubljana,
Biotechnical
Faculty,
Departement
of
Wood
Science
and

Technology,
Ljubljana,
Slovenia,
nejc.thaler@bf.uni-­‐lj.si

5
University
of
Ljubljana,
Biotechnical
Faculty,
Departement
of
Wood
Science
and

Technology,
Ljubljana,
Slovenia,
mojca.zlahtic@bf.uni-­‐lj.si

Keywords:
thermal
modification,
water
uptake,
laboratory
tests,
field
test,
moisture
content

Thermal
modification
of
wood
is
one
of
the
most
important
modification
processes.
Properties
of

this
material
predominately
depend
upon
the
modification
process,
temperature
of
modification

and
its
duration.
Mass
loss
during
modification
is
one
of
the
parameters
that
characterise
the

modified
wood.
In
general,
higher
temperatures
and
longer
modification
processes
result
in

higher
mass
loss.
Thermal
modification
results
in
improved
durability.
The
reasons
for
increased

durability
can
be
attributed
to
the
lower
equilibrium
moisture
content,
better
dimensional

stability
and
formation
of
new
toxic
compounds.
In
recent
research
another
aspect
has
drawn

considerable
attention,
namely
water
exclusion
efficacy.
Although
the
importance
of
this

parameter
has
been
identified
in
the
new
edition
of
the
EN
350
(2015)
durability
standard,
there

is
still
not
an
optimal
method
developed
for
elucidation
of
this
parameter.
The
aim
of
this
study

was
to
compare
various
water
uptake
techniques
with
field
test
methods.

Specimens
were
made
of
Norway
spruce
heartwood.
Two
types
of
the
specimens
were
prepared.

2.5
cm
×
5.0
×
cm
×
50
cm
(EN
252
size)
and
1.5
×
cm
×
2.5
cm
×
5.0
cm
(EN
113
size).
They
were

thermally
modified
at
seven
temperatures:
25
°C,
160
°C,
180
°C,
190
°C,
200
°C,
210
°C,
and
230

°C.
The
modification
duration
was
three
hours.
The
process
was
performed
following
Rep
and

Pohleven
(2004).
Mass
loss
of
the
specimens
was
determined
gravimetrically.
Four
were
sets
of

tests
performed.
In
the
first
set
EN
252
sized
samples
were
soaked
in
water
for
periods
between
8

h
and
4
days
and
were
then
positioned
on
load
cells
(HMB
load
cells,
PMX
amplifier,
Catmaneasy

recording
software)
and
were
allowed
to
dry
until
a
constant
mass
was
reached.
In
the
second

experiment,
short
term
water
uptake
was
determined
with
a
tensiometer
(Krüss)
as
described
by

43