Mechanical properties of colombian glued laminated bamboo
Juan F. Correal
Director of Integrated Civil & Environmental Engineering Lab & Assistant Professor,
Universidad de Los Andes
Bogotá, Colombia
(Luis F. López , Graduate Research Assistant, Universidad de los Andes, Bogotá, Colombia)
Summary: A study is conducted to establish the suitability of Colombian glued laminated bamboo
(Guadua Angustifolia Kunt) for structural applications. As part of this study, selected mechanical
properties are reported in this paper. Results confirm that glued laminated Guadua (GLG) has
similar mechanical properties to best structural wood in Colombia. A comparison of the mechanical
properties obtained in this research with the corresponding data reported around the world indicates
that GLB can be suitable material for construction and design of structural elements.

1. Introduction
About 52,000 hectares of specie of bamboo called Guadua Angustifolia Kunt grows naturally in some
regions in Colombia. Only 40% of the Guadua bamboo is used in structural applications, mainly as
material for falsework in the construction of concrete floors. In the country, there has been some
intent to use Guadua bamboo as structural material with a relative good success. Nevertheless, one
of the problems with the Guadua culm is the variability of the mechanical properties. Taking into
account the currently standardization of the construction industry, glued laminated Guadua has
surged as an excellent alternative for a proper prefabricated manufacturing and assembly
construction process of structural elements. Preliminary research (Duran, 2003 and Vanegas, 2003)
indicated that the laminated Guadua has an excellent mechanical properties and it is as good as the
best structural wood in Colombia.
The Universidad de Los Andes in Bogotá is conducting for the first time in Colombia a detailed
study of the structural performance of the glued laminated Guadua. This research consists of
physical and mechanical characterization, strength verification of structural elements, behavior of
typical connections and seismic validations of construction system. Selected mechanical properties
of the glued laminated Guadua like: compressive strength perpendicular and parallel to grain,
tensile strength perpendicular to grain, flexural strength, shear strength parallel to grain and internal
bond strength are presented in this paper. A comparison of the mechanical properties obtained in

this research with the corresponding data reported around the world is shown.

2. Material and production method
2.1 Material
Guadua bamboo culms with and average base diameter of 14 cm to 7 cm and height of 30 m are
obtained from Caidedonia-Valle in Colombia. The average thickness of the culm wall varies from
0.8 cm to 2.0 cm. The age of the bamboo varies from 4 to 6 years. The culms are cut into 2 to 3
meters lengths and they are taking into the warehouse of the factory.
2.2 Production Method
The manufacture of the laminated Guadua is made in Colguadua Ltda factory. The culms sections
of 2m to 3m are cut again into 1m to 1.5m in order to have straight pieces. Each piece is split in the
radial direction into proper number of slices and the node sections are removed. The slices are dried


in oven to an average of 6% to 8% moisture content. Once the slices are dried, they are immersed in
chemical solution to protect bamboo against insects attack. Each slice is machined by cutting off the
inner and outer faces and form Guadua lamina with thickness from 7 mm to 10 mm. All laminas
are impregnated with polyvinyl acetate (PVA) adhesive and staked to form laminated Guadua
sheeting. Each laminated Guadua is cold pressed in hydraulic press at a pressure of 2 MPa for 15
minutes.

3. Experimental program
Temperature, moisture content and relative humidity were recorded for all specimens. Tests were
conducted on a MTS Universal Testing Machine at the Material Lab at the Universidad de Los
Andes in Bogotá, Colombia. All the specimens follow the specifications of the Colombian Institute
of Standards Techniques (ICONTEC) for woody materials which are based on ASTM D143-52 of
1997 standards. Test procedures are summarized as follows:
Compression Parallel to Grain- ICONTEC 784
The specimens were 50 mm by 50 mm in section and 200 mm in length. A continuously
compression load with load rate of 0.6mm/min was applied. The load-displacement curve is

recorded and the modulus of elasticity (MOE), the proportional limit stress and the ultimate stress
are determined.
Compression Perpendicular to Grain -ICONTEC 785
The specimens were 50 mm by 50 mm in section and 150 mm in length. MTS load frame with a
bearing metal plate width 50 mm was used to apply a continuously compression load with load rate
of 0.3mm/min. The load was applied up to deformation equal to 5% of the specimen thickness is
reached and the stress at that point is calculated. The proportional limit stress
Flexural Strength- ICONTEC 663
The specimens were 25 mm by 25 mm in section and 410 mm in length. The load was applied at the
center of 350 mm span with load rate of 2.5mm/min. The failure load is recorded and the module of
rupture (MOR) is calculated.

Load
Direction

(a)

(b)

Fig. 1. Tensile Strength perpendicular to grain

Tensile Strength perpendicular to grainICONTEC 784
Figure 1 presents the dimensions of the
tensile test specimen. The load was applied
continuously throughout the test at the rate
of the movable crosshead of 2.5 mm/min.
Ultimate tensile stress is calculated.


Shear Strength Parallel to GrainICONTEC 775


Load
Direction

(a)

Shear parallel to grain was performed based
on. Dimensions of the specimen as well as
the test setup are shown in Figure 2. The
load was applied continuously throughout
the test at the rate of 0.6 mm/min. Ultimate
shear stress is calculated.
(b)

Fig. 2. Shear Strength Parallel to Grain
Internal Bond Strength

Load
Direction

(a)

The block-type glue-line shear test
was used to evaluate internal bond
strength and it is based on ASTM
D1037. Figure 3 presents the
dimensions of the test specimen and
setup. The load was applied through a
self aligning seat with a continuous
motion of the movable head of the

testing machine of 0.6mm/min. Shear
stress at failure based on maximum
load is determined.

(b)

Fig. 3. Internal Bond Strength

4. Results and discussion
Test average results with the corresponding number of specimens, temperature, average moisture
content and relative humidity are shown in Table 1. An average of 19.7 oC, 11.7 %, and 66.7% of
temperature, moisture content and relative humidity were recorded at the moment of the test. Also
in Table 1, the 5th percentiles of the results and the corresponding mechanical properties of the
structural wood according to Colombian Seismic Regulations (NSR, 1998) are shown for
comparison.
Glued Laminated Guadua
Test

Compresion parallel to
grain
Compresion
perpendicular to grain
Tension perpendicular
to grain

N°

T (°C)

MC (%) RH (%)


σult= 47.6

33
32
31

20.5

10.44

63.06

29

19.23

10.15

67.57

20.18

12.64

62.59

17

Result (MPa)


σpl= 35.71
MOE= 19,140
σpl= 5.4
σult= 1.49

Static bending

21

21.03

12.76

66.4

MOR= 81.9

Shear parallel to grain

30

18.08

10.79

70.18

σult= 9.32


Glue-line shear test

32

70.56

σult= 7.92

19.25

13.44

NSR-98 Wood Grade
5% Percentil (MPa)

VC
(%)

5% Percentil
(MPa)

5.42

σult=

5.48
8.49

σpl=
MOE=


14.66

σpl=

2.63

σpl=

6.5

4.57

2.45

σult=

0.76

σult=

ND

ND

ND

14.79 MOR=

60.66


MOR= 68.45

48.89

32.6

12.63

σult=

7.68

σult= 6.12

4.9

3.27

12.29

σult=

6.64

σult=

ND

ND


29.9

43.59
32.79
16,000.0

A

B

σult= 29.59
σpl= ND
MOE= ND

ND

22.45
ND
ND

C
16.33
ND
ND

N°: Number of Specimens, T: Temperature, MC: Moisture content, RH: Relative Humity, σutl: Ultimate Stress, σpl:
Proportional Limit Stress, MOE: Elasticity Modulate, MOR: Modulus of rupture, VC: Variation Coefficient.

Table 1. Summary of Test Results of Glued Laminated Guadua (GLB)



The compression parallel to grain (CPAG) test showed a combination of crush with buckling failure
for most of the specimens. The 5% percentile value of the ultimate stress for CPAG is 47% higher
than the best Colombian wood (type A). The failure mode of the compression perpendicular to grain
(CPEG) test was crushing of the material. Relatively low value of the 5th percentile was achieved in
CPEG test compare to Colombian wood. An additional CPEG test was performed with load applied
to four specimens with vertical adhesive line. As a result, the ultimate stress for CPEG with vertical
adhesive line increased to 41% compare to CPEG with horizontal adhesive line.
Adhesive failure was observed in all the specimens of the tension perpendicular to grain (TPG) test.
It seems that the adhesive spread rate was not constant during the construction process of these
specimens which could explain the high variation coefficient obtained in the TPG test. Delimitation
failure was presented in most of the specimens of the static bending (SB) test. MOR obtained from
the SB test is comparable to the type B Colombian wood. The failure mode observed in the shear
parallel to grain (SPG) test was shear-off the bamboo specimen. The shear strength from SPG test is
25% higher compare to Colombia wood type A. The glue-line shear test specimens failed in the
interlaminate adhesive as expected
A comparison of compression parallel to grain (CPAG) stress of GLG with different adhesive is
shown in Table 2. There was no different between the CPAG stress of GLG with Polychloroprene
and the CPAG stress of GLG with PVA. In addition, the CPAG stress of GLG with PVA is similar
in magnitude compare with the higher CPAG stress of GLG with urea-formaldehyde resin (UFR).
AUTHOR

BARRETO W.

DURÁN L.

CORREAL J.,
LOPEZ L.


YEAR

2003

2003

2007

BAMBOO

Guadua
angustifolia kunt

Guadua
angustifolia kunt
Guadua
angustifolia kunt

ADHESIVE

COMPRESION
PARALLEL TO
GRAIN (MPa)

Urea
Formaldehyde
Resin

47.2


Polychloroprene

46.5

Urea
Formaldehyde
Resin

34.0

Polychloroprene

46.5

Polyvinyl of
Acetate (PVA)

47.6

Table 2. Comparison of Compression Parallel to Grain Stress of GLB
Table 3 shows a comparison of internal bond (IB) strength and MOR of glued laminated Guadua
(GLG) and glued laminated Moso bamboo (GLM). The IB strength for PVA adhesive is higher
compare to UFR adhesive when it is used in GLG. Disregarding the adhesive type, the IB strength
is higher in GLG compare to GLM. The different in IB strength in GLB and GLM can be associated
with different adhesive spread rates. Nonetheless, it seems that the differences in IB strength
between GLG and GLM did not affect the MOR. Whereas IB strength between GLG and GLM
differ in about 372%, MOR between GLG and GLM differ only 20%. It appears that once the
optimum amount of adhesive is achieved, the IB strength do not have a significant affect on the
MOR (Nugroho and Ando, 2001).



AUTHOR

YEAR

BAMBOO

ADHESIVE

INTERNAL
BOND (MPa)

BEAM
TYPE

STATIC BENDING
MOR (MPa)

BARRETO W.

2003

Guadua
angustifolia kunt

UFR

3.91.

ND


ND

DURÁN L

2003

Guadua
angustifolia kunt

UFR
PCP
PVA

3.01
5.67
4.22

ND

ND

2007

Guadua
angustifolia kunt

PVA

7.92


ND

81.9

1998 Moso Bamboo

RFR

2.13

2000 Moso Bamboo

E-MDI

0.81

2001 Moso Bamboo

RFR

0.59

CORREAL J.,
LOPEZ L.
LEE A., BAI X.,
BANGI A. P.
NUGROHO N.,
ANDO N.
NUGROHO N.,

ANDO N.

H-beam
V-beam
ND
H-beam
V-beam

98.6
104.8
76.84
70.31
77.04

UFR: Urea Formaldehyde Resin, PCP: Polychloroprene, PVA: Polyvinyl of Acetate, RFR: Resorcinol Formaldehyde
Resin, E-MDI: Emulsion methyldiisocayanate resin

Table 3. Comparison of Internal Bond Strength and MOR for GLB and Glued Laminated Moso
Bamboo

5. Conclusion
Based on the preliminary results of this research, the following conclusions are drawn:
Glued laminated Guadua (Colombian Bamboo) has comparable mechanical properties than
structural Colombian wood. In some cause, the mechanical properties of the GLG are better than
the best structural wood in Colombia.
The compression parallel to grain stress is not affect by the type of adhesive and the internal bond
strength in glued laminated Guadua.
Modulus of rupture for glued laminated Guadua and glued laminated Moso is not affected by the
internal bond strength once the optimum amount of adhesive is achieved. In general the MOR of the
glued laminated Guadua is comparable with glued laminated Moso.

Based on the comparison to structural Colombian wood and glued laminated Moso bamboo, the
glued laminated Guadua can be suitable material for construction and design of structural elements.
Acknowledgement
The research presented in this paper is sponsored by Universidad de Los Andes. Thanks are to A.
Arias of Colguadua and the staff of the Material Lab at the Universidad de Los Andes in Bogotá,
Colombia for their help and support.

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