celluwood project final workshop results

CELLUWOOD Project Final Workshop

4th September 2014, Lleida (Spain)

AIDIMA Miguel Ángel Abián

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WP 8: ASSESSMENT OF CELLUWOOD

MATERIAL

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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

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6

7

8

9

10

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12 PUR beams

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14

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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)

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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

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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.

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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.

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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.

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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.

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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.

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3. NON-DESTRUCTIVE TESTS (ULTRASOUNDS)

PUR BEAMS

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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

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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

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LIGNIN BEAMS

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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).

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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

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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

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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

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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

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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

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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

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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

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Breaking of a commercial MUF beam

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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)

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Breaking of a lignin beam (separation of the lamellas)

53 Breaking of a lignin beam (crack)

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Breaking of a lignin beam (crack)

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10000

12000

14000

16000

18000

20000

22000

24000

MOE (MPa)

MUF

PUR

LIGNIN

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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)

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40

45

50

55

60

65

70

75

MOR (MPa)

MUF

PUR

LIGNIN

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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