Course No: CE 4000

INVESTIGATION ON THE PERFORMANCE OF BAMBOO REINFORCED CONCRETE BEAMS

Supervised By:MUHAMMAD HARUNUR RASHID

Presented By:MOHAMMAD TAREQ HASAN (0401103)

MD. KAMRUL HASAN (0401090)

INTRODUCTION

• Bamboo is giant grass, not a tree and culms are a cylindrical shell divided by solid transversal diaphragms at nodes.

• It has high strength in the direction parallel to the fibers, which run longitudinally along the length of the culm, and low strength in a direction perpendicular to the fibers.

• It is also light weight & much economic than steel.• In some parts of the world many buildings are constructed only with concrete or

mud-bricks &this is dangerous in case of seismic activity. Steel reinforcement would be an ideal solution, but cost is a considerable problem.

• Scientists and engineers are constantly seeking for new materials for structural systems; the idea of using bamboo as possible reinforcement has gained popularity.

• So if bamboo can be used as reinforcement instead of steel, it will be a great achievement.

OBJECTIVE

• To investigate the behavior of bamboo as reinforcement.

• Construction of bamboo reinforced beam and compare with plane beam .

TENSILE TEST OF BAMBOO STICKS

Specimen Preparation:

• In order to conduct the tensile tests, it was necessary to prepare the bamboo samples. • First, the samples were cut to the proper size and shape. • The sticks was prepared about 16mm – 18mm diameter for tensile strength test.• Sticks was chosen from different position of a whole bamboo which have different

node numbers.• Length of the samples were 1 m.

1m

17 mm

Figure 1:Length Figure 2:Diameter

Figure 3: Test setup for tensile test

Test setup:

• For tensile strength testing a Universal Testing Machine was used. This machine is able to apply tensile loads which is shown in Figure 3.

• Specimen was placed in Universal Testing Machine and pulled out until it was crushed.

BEAM TESTBEAM DESIGN:

• In the beginning of the beam design, the width and depth of 06 in was assumed and length was 2.5 ft, along with a diameter of the bamboo bars of ¾ in (19 mm).

• Clear cover was 1 in.• Four types of beams was design which all beans were same dimension but only they vary

with respect to positioning of bamboo sticks.

1”1”

6”5”

1”

1”

6”

1”

1”

6”5”

1”

Reinforced at bottom Reinforced on top Reinforced at both layer

5”

Concrete Mix Design :

The concrete used for the beams was made using ordinary Portland Cement, sand as the fine aggregate and stone chips as coarse aggregate with a maximum size of 3/4 in (19 mm).

The concrete mix proportions were 1:2.75:3 (cement: fine aggregate :coarse aggregate) and a water-cement ratio was 0.60.

The mix was designed for 28 day strength of 3000 psi , and a slump value of approximately 2-4in to insure consistency concrete.

Table 1: Ingredients for Concrete Mixture

Water(kg/m3)

Cement(kg/m3)

Fine Aggregate (kg/m3)

Coarse Aggregate(kg/m3)

190 315 957 877

Formwork :

•Formwork was constructed to support the freshly placed concrete and the bamboo reinforcement of the beam.•Ready metal formwork was used which is shown in figure 4.

Figure 4: Formwork

Pouring of concrete:

• A typical beam had the dimensions of 2.5 ft x 6in x 6 in and the volume of 0.625 ft3 . A single beam’s concrete mix was then reduced from the original mix design and designed for a rounded 0.75 ft3 mix. The mix for a 0.75 ft3 beam is shown in Table 2.

• After mixing concrete was placed & as well as reinforcement also placed into the formwork and 1 in clear cover was confirmed.

• Using vibrator, the concrete was pushed down in between the reinforcement as well as in the more open areas to help ease out air pockets.

• When all the concrete was added to the formwork, the top was finished off smoothly and the curing process began.

Water(Litter)

Cement (kg)

CoarseAggregate (kg)

FineAggregate(kg)

3.5 6 18 16.8

Table 2 : Ingredients for Concrete Mixture (One Beam)

2.5 ft

0.5 ft

0.5

ft

Beam construction process :

Compression Tests :

•Cylinders were also prepared (as per ASTM standards) for compression tests.•This was done by pouring them full of the same concrete used in the beam. •Then the cylinders cured 28 days to tell the full strength of concrete.•To find the strength of the concrete, the cylinders were placed under a compressive load using a hydraulic compression machine.

Figure 6:Prepared beam

Figure 5:Curing of beams

Test setup:

The beam was placed carefully to provide the supports at the measured placement of 5 in (125 mm) from each end.

The beam was then placed under the testing machine as shown in Figure 7. A dial gauge was also provided for measuring deflection

After placing the beam, one point load at the middle of the beam was applied gradually by hand pump.

Figure 7: Test setup

Jack

Dial gauge

20”5” 5”

L/2

Load on beam:

EXPERIMENTAL TEST RESULTSTensile Test Results :

• Tensile tests was performed on different species of Bamboo .

• These tests were performed on several specimens with 3 nodes and 5 nodes.• The failure often occurred at the node as shown in Figures 8 and stress-strain curve

are shown in figure 9.

No Dia (mm)

Area(mm)

Length(mm)

Wt(gm)

Node no UltimateLoad (kN)

Stress(ksi)

1 17.5 240.5 1000 172.7 3 23.87 14.39

2 18.1 257.3 1000 217.2 3 28.53 16.08

3 17.1 229.7 1000 171.0 3 23.56 14.9

4 17.9 251.6 1000 181.5 5 24.39 14.05

5 18.7 274.6 1000 223.0 5 29.35 15.5

6 18.2 260.1 1000 201.4 5 27.00 15.05

Table 3: Tensile test result of bamboo sticks

0 1 2 3 4 5 60

2

4

6

8

10

12

14

16

18

Stress Vs Strain

Strain %

Str

ess (

ksi)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

2

4

6

8

10

12

14

16

Stress Vs Strain

Strain %

Str

ess (

ksi)

Figure 2: Stress Vs Strain curve for 3 node bamboo sticks

Figure 2: Stress Vs Strain curve for 5 node bamboo sticks

Failure from nodes

After failure

Beam Tests Results :

Beam type Plane beamBottom

ReinforcedBeam

TopReinforced

Beam

Top & bottom Reinforced

Beam

Ultimate Load(kN) 4.9 16.2 14.7 21.7

Deflection at middle point

(mm)2.3 6.4 4.5 7.5

Table 5: Load test result (four samples)

Sample no. 7 days (psi) 28 days(psi)

1 1742 2560

2 2114 2835

3 1943 2792

Compression test result :

Table 4: Cylinder test result

Crack

Figure 8:Failure of beam

Constraints : • Bamboo sticks are not accurately straight. • Bamboo sticks can slip when it is tested on UTM, so actual elongation

measurement is very difficult. • Bamboo is a living organism which is subject to fungi and insect attacks.

• Shape & size of bamboo reinforcement changes with climatic condition.

Conclusion and Recommendations

Tensile tests indicated that presence of nodes in bamboo samples did not affect the behavior. The constitutive relationship of the nodes differs from those of inter-nodal regions with nodes having a brittle behavior while inter-nodal regions exhibit a more ductile behavior. Bamboo sticks are use only for flexure in beam. By using bamboo reinforcement in both layer, load capacity increases about 4 times with respect to plane beam.

This project may suggests some recommendations for future research.

• Long-term studies investigating the durability of Bamboo reinforced concrete should be conducted.

• Different beam dimensions are suggested to be used.• The same test can be performed by using steel stirrups to create a hybrid beam.

THANKS TO ALL