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CELLUWOOD Project Final Workshop
4th September 2014, Lleida (Spain)
Eco-beams results
AIDIMA Miguel Ángel Abián
2
WP 8: ASSESSMENT OF CELLUWOOD
MATERIAL
The overall objective of this WP is to test and
characterize the CELLUWOOD materials developed in the
previous WPs. This presentation is focused on the
results from beams.
3
Previously, in WP7 some lignin, PUR and MUF beams where manufactured at
TECNIFUSTA for interim testing. Those interim tests led to changes in the
formulation of the lignin resin by CHIMAR in order to achieve a satisfactory and
effective final resin.
In 2014, 20 complete beams (nominal dimensions: 120 x 120 x 2200 mm) were
manufactured at TECNIFUSTA in collaboration with CHIMAR and AIDIMA:
• 10 beams with their lamellae glued by the final lignin resin developed in the
project (CELLUWOOD beams).
• 10 beams with their lamellae glued by commercial PUR.
All lamellae were made of timber classified as C24.
10 commercial beams (nominal dimensions: 120 x 120 x 2200 mm) made with MUF
resin were used in order to compare strength and behaviour with the other 20 beams.
The commercial beams are classified as GL24h.
All beams were made of Picea abies wood.
1. MANUFACTURING OF THE BEAMS TO BE TESTED
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Measurement of the moisture content of timber
Preparation of the lignin resin for its
application
5
6
7
8
9
10
11
12 PUR beams
13
14
15
Shear test of glue lines
EN 392 (Glued laminated timber. Shear test of glue lines).
2. PERFORMANCE OF THE GLUE LINES IN CELLUWOOD
BEAMS (LIGNIN RESIN)
16
According to EN 386, the shear
strength of each glue line shall be
at least 6,0 N/mm2. RIGHT
0
1
2
3
4
5
6
7
8
9
10
1 2 3 4 5 6 7 8 9 10
She
ar s
tre
ngt
h (
N/m
m2
) Shear strength (fS) of the glue line 1
0
1
2
3
4
5
6
7
8
9
10
1 2 3 4 5 6 7 8 9 10
She
ar s
tre
ngt
h (
N/m
m2
)
Shear strength (fS) of the glue line 2
17
According to EN 386 RIGHT
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9 10
PW
F (%
) Percentage wood failure (PWF) of the glue
line 1
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10
PW
F (%
)
Percentage wood failure (PWF) of the glue line 2
All test pieces fulfilled the requirements of EN 386 (Glued laminated timber. Performance
requirements and minimum production requirements) regarding shear strength and
wood failure percentage (EN 392). These results point out very clearly that gluing Picea
abies lamellae with the lignin resin is very effective.
Average value SD
fS (N/mm2) 7.37 0.75
PWF (%) 66.0 16.4
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Delamination of glue lines
EN 391 (Glued laminated timber. Delamination of glue lines)
EN 391 is a glulam production standard, which determines if the product is “up to
standard”. This test method measures the delamination of flue lines after a treatment
consisting of soaking in water followed by fast drying at a high temperature; that is, in
effect, an accelerated ageing test method.
Stresses in the wood perpendicular to the glue line put a strain on the joint, which either
fails in the flue line (causing a delamination), or creates cracks in the wood. If the
delamination value after treatment is low (0% after one cycle, <5% after 2 cycles and
<10% after 3 cycles using Method A, which is the treatment method for glulam in service
class 3 according to EN 386), the bonding is seen as being successful, and the product
can go to the market.
19
After each of the three cycles specified in Method A of EN 391, the total delamination
percentage and the maximum delamination percentage were 0% for all 10 samples.
Therefore, the samples fulfilled the requirements of EN 386 for glue integrity in
structures of service class 3.
Considering this and the results from EN 392, all samples fulfilled the requirements of
EN 386 regarding glue line integrity and strength for structures of service class 3.
Pressure vessel used by AIDIMA for the first two cycles of Method A (EN 391)
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Two test samples after extracting them from the pressure vessel,
following Method A (EN 391).
Test sample after the final
drying process specified
in Method A (EN 391).
There is no delamination
in the glue lines.
21
All 10 beams were conditioned were in normal environment conditions (relative humidity
65 + 5 %; temperature 20 + 2º C) for 7 days. The points used for measuring moisture
content are shown in the following figure.
3. MOISTURE RESISTANCE OF CELLUWOOD BEAMS
(LIGNIN RESIN)
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The maximum difference in moisture content between lamellas is <2%, so the dimensional
stability of CELLUWOOD beams is excellent.
23
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Volumetric shrinkage
The standards used for determining the volumetric shrinkage of CELLUWOOD beams were a
combination of UNE 56533 (Physical-mechanical characteristics of wood. Determination of
linear and volumetric shrinkage) and ISO 4858 (Wood - Determination of volumetric shrinkage)
standards.
The International Standard specifies two methods for the determination of the volumetric
shrinkage of wood. The method chosen in the project was the mercury volumenometer method,
used for test pieces of any shape.
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Sample βν (%) ν (%) SL (parallel to
glue line) (%)
SL (parallel to
glue line) (%)
SL (longitudinal) (%)
1 10.82 0.25 4.18 5.02 1.16
2 10.33 0.27 4.01 4.46 1.23
3 10.76 0.26 3.96 5.14 1.07
4 10.32 0.30 4.01 4.67 1.03
5 10.45 0.25 4.11 4.81 1.18
6 10.34 0.29 4.00 5.08 1.14
7 9.98 0.24 4.14 4.74 1.01
8 10.43 0.28 3.95 5.06 1.11
9 10.64 0.31 4.14 4.91 1.20
10 10.91 0.25 4.19 4.87 1.12
Average 10.50 0.27 4.07 4.88 1.13
Standard
deviation 0.28 0.02 0.09 0.21 0.07
Total volumetric shrinkage: βν
Volumetric shrinkage coefficient: ν
Total linear shrinkage: SL
The total volumetric shrinkage (10.5%) and the volumetric shrinkage coefficient (0.27%) are
significantly lower than those corresponding to Norway spruce timber used for the beams
(12.6% and 0.45%, respectively). With respect to shrinkage, CELLUWOOD beams are
appropriate for outdoor use. They have a good dimensional behaviour regarding
shrinkage, compared with standard timber.
26
Volumetric swelling
The standard used for determining the volumetric swelling of the CELLUWOOD beams was
ISO 4860 (Wood - Determination of volumetric swelling). That Internation Standard specifies
two methods for the determination of the volumetric swelling of wood. The method chosen in
the project was the mercury volumenometer method, used for test pieces of any shape.
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Total volumetric swelling: ανmax
Volumetric swelling: ανn Sample ανmax (%)
ανn (%)
1 10.13 2.87
2 9.91 3.10
3 10.31 2.93
4 10.40 3.21
5 10.28 2.97
6 10.02 3.01
7 9.96 2.85
8 10.38 2.93
9 10.09 3.11
10 10.21 2.90
Average 10.17 2.99
Standard
deviation 0.17 0.12
The total volumetric volumetric swelling (10.17%) is significantly lower than those
corresponding to Norway spruce timber used for the beams (13.2%). With respect to
swelling, CELLUWOOD beams are appropriate for outdoor use. They have a good
dimensional behaviour regarding swelling, compared with standard timber.
28
29
3. NON-DESTRUCTIVE TESTS (ULTRASOUNDS)
PUR BEAMS
30
Results for PUR beams:
• Good quality timber in all lamellae: C24-C40
• MOE of lamellae between 10900 and 15700 N/mm2
• All glue lines without cracks, holes or discontinuities
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COMMERCIAL MUF BEAMS
GL24h
32
Results for commercial MUF beams:
• Good quality timber in all lamellae: C24-C40
• MOE of lamellae between 11551 and 14897 N/mm2
• All glue lines without cracks, holes or discontinuities
33
LIGNIN BEAMS
34
Results for lignin beams:
• Good quality timber in all lamellae: C20-C40
• MOE of lamellae between 10425 and 16534 N/mm2
• All glue lines without cracks, holes or discontinuities
4. MECHANICAL PROPERTIES OF SMALL SAMPLES FROM
CELLUWOOD BEAMS
STANDARD RESULT
Density (kg/m3) UNE 56531 498
Moisture content (%) EN 12183-1 10.4
Bending strength (N/mm2) UNE 56537 80.1
Modulus of Elasticity UNE 56537 10160
Total volumetric shrinkage (%) UNE 56533 12.6
Shrinkage coefficient (%) UNE 56533 0.45
Linear shrinkage. Radial direction (%) UNE 56533 4.14
Linear shrinkage. Tangential direction (%) UNE 56533 7.78
Linear shrinkage. Longitudinal direction (%) UNE 56533 0.26
Higroscopicity (kg/cm3) UNE 56532 0.0025
Axial compression C12 (kg/cm2) UNE 56535 476
Compression strength perpendicular to grain.
Radial face (N/mm2) UNE 56542 97.5
Compression strength perpendicular to grain.
Tangential face (N/mm2) UNE 56542 95.6
Shear strength (N/mm2) UNE 56543 73.6
Tension strength perpendicular to grain. Radial
direction (N/mm2) UNE 56538 11.6
The general properties of the Norway spruce (Picea abies) timber used in CELLUWOOD beams
were determined at AIDIMA Laboratories.
Each value shown in the table is the average value of 30 samples (3 samples from each beam).
35
According to EN 408:2010, mechanical properties were determined in small samples of
CELLUWOOD beams made of Norway spruce (Picea abies) lamellae glued with the final
lignin resin developed in the project. When possible, the dimensions of the samples
maintained the real geometry of the lamellae of which beams are made.
Bending strength (MOR) and global modulus of elasticity (MOE)
Sample Bending strength
(N/mm2)
Global modulus of
Elasticity (N/mm2)
1 71.28 12580
2 73.12 11623
3 81.03 12961
4 76.25 12098
5 68.67 11483
6 78.24 12856
7 74.91 12755
8 66.94 12136
9 72.27 13546
10 78.23 13865
Average 74.09 12590
Standard
deviation 4.48 773
Characteristic value of MOR
for glulam classified as
GL24h: 24 N/mm2
Characteristic value of MOE
for glulam classified as
GL24h: 11600 N/mm2
36
Compression strength parallel to grain
Sample Compression strength
parallel to grain
(N/mm2)
1 42.50
2 44.12
3 40.21
4 44.62
5 41.37
6 44.06
7 42.48
8 43.81
9 41.95
10 44.23
Average 42.94
Standard
deviation 1.46
Characteristic value of this
property for glulam classified
as GL24h: 24 N/mm2
Characteristic value of this
property for glulam classified
as GL36h: 31 N/mm2
37
Compression strength perpendicular to grain
Sample Compression strength
perpendicular to grain
(N/mm2)
1 3.93
2 4.19
3 4.23
4 3.91
5 4.11
6 3.85
7 4.18
8 3.96
9 4.12
10 3.88
Average 4.03
Standard
deviation 0.14
Characteristic value of this
property for glulam classified
as GL24h: 2.7 N/mm2
Characteristic value of this
property for glulam classified
as GL36h: 3.6 N/mm2
38
39
Shear strength
Sample Shear strength
(N/mm2)
1 6.60
2 5.51
3 5.93
4 6.07
5 6.23
6 5.79
7 6.01
8 5.86
9 6.33
10 5.98
Average 6.03
Standard
deviation 0.30
Characteristic value of this
property for glulam classified
as GL24h: 2.7 N/mm2
Characteristic value of this
property for glulam classified
as GL36h: 4.3 N/mm2
40
41
Tension strength parallel to grain
Sample Tension strength parallel
to grain (N/mm2)
1 21.31
2 20.67
3 19.48
4 20.71
5 21.46
6 19.92
7 20.52
8 19.78
9 20.07
10 21.56
Average 20.55
Standard
deviation 0.73
Characteristic value of this
property for glulam classified
as GL24h: 16.5 N/mm2
Characteristic value of this
property for glulam classified
as GL28h: 19.5 N/mm2
42
Tension strength perpendicular to grain
Sample Tension strength
perpendicular to grain
(N/mm2)
1 1.92
2 1.77
3 1.56
4 1.89
5 1.48
6 1.79
7 1.84
8 1.43
9 1.91
10 1.42
Average 1.70
Standard
deviation 0.21
Characteristic value of this
property for glulam classified
as GL24h: 0.4 N/mm2
Characteristic value of this
property for glulam classified
as GL36h: 0.6 N/mm2
43
44
45
EN 408:2011+A1:2012 Timber structures – Structural timber and glued laminated timber
– Determination of some physical and mechanical properties specifies test methods for
determining most of the strength and stiffness properties of structural and glued
laminated timber.
Section 19. Determination of bending strength
Section 10. Determination of global modulus of elasticity in bending
5. MECHANICAL PROPERTIES OF CELLUWOOD BEAMS
DETERMINED FROM FULL-SIZE SPECIMENS
46
47
Breaking of a commercial MUF beam
48
Breaking of a commercial MUF beam
49 Breaking of a PUR beam
50 Breaking of a PUR beam
51 Breaking of a lignin beam (separation of the lamellas)
52
Breaking of a lignin beam (separation of the lamellas)
53 Breaking of a lignin beam (crack)
54
Breaking of a lignin beam (crack)
55
10000
12000
14000
16000
18000
20000
22000
24000
MOE (MPa)
MUF
PUR
LIGNIN
56
The
average
MOE for
lignin
beams is
45%
greater
than the
average
MOE for
MUF
beams
12425
15135
18027
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
MUF PUR LIGNIN
Average MOE (MPa)
57
40
45
50
55
60
65
70
75
MOR (MPa)
MUF
PUR
LIGNIN
58
The
average
MOR for
lignin
beams is
23%
greater
than the
average
MOR for
MUF
beams
49,6
51,2
61,0
40
45
50
55
60
65
MUF PUR LIGNIN
MOR (MPa)
Thank you very
much for your
attention Project coordinator at AIDIMA: Miguel Ángel Abián