Bamboo Reinforced Concrete

Introduction

Bamboo has been used as a construction material in certain area for centuries. A study of bamboo is used as a reinforcement in precast concrete elements was carried out in U.S. Army Engineer Waterway experiment station in 1964.
Bamboo was given recent consideration for use as reinforcement in soil cement pavement slabs in which the slabs behave in elastically even under light loads.
Bamboo is characterized as a bio degradable, renewable and an energy efficient natural resource.
It is an environmentally sustainable building material.
Bamboo can be used as an alternative material in reinforcement of concrete.

Characteristics of Bamboo Reinforced Concrete

Bamboo can prevent pollution.
The specific gravity of bamboo varies between 0.4 to 0.5
The strength of bamboo is greater than most of the timber products.
Bamboo is giant grass not a tree.
The ratio of tensile strength to specific weight of the bamboo is about 6 times that of steel.
The density of fibres in cross-section of a bamboo shell varies with thickness as well as height.
Bamboo is more prone to insect attack than other trees and grasses.

Selection of Bamboo

Use only bamboo showing a pronounced brown color. This will insure that the plant is at least three years old.
Do not use whole culms of green, unseasoned bamboo.
Avoid bamboo cut in spring or early summer. These culms are generally weaker due to increased fiber moisture content.
Select the longest large diameter culms available.

Preparation

Concrete Mix Proportions

The same mix designs can be used as would normally be used with steel reinforced concrete.
Excess water causes swelling of the bamboo.
Concrete slump should not as low as workability will allow.
High-early strength cement is preferred to minimize cracks caused by swelling of bamboo when seasoned bamboo cannot be waterproofed.

Bamboo as an Engineering material

Comparison of Steel and Bamboo

Placement of Bamboo

Bamboo reinforcement should not be placed less than 1.5 inches from the face of the concrete surface.
The clear spacing between bamboo rods or splints should be less than the maximum size aggregate plus ¼ inch.
The ties can be made with vegetation strips.
Spacing of the stirrups should not exceed 6 inches.
Reinforcement should be evenly spaced and lashed together on short sticks placed at right angles to the main reinforcement.

Effect of water absorption

The main shortcomings of bamboo is its property of water absorption.
The dimensional variation of untreated bamboo due to water absorption can cause micro or even macro cracks in cured concrete.
This can be controlled by treating the bamboo.

Advantages of Reinforced Bamboo Concrete

Conclusion

It is a boon for light weight and temporary buildings.
The environmental and financial comparison demonstrates that bamboo can compete as a building material.
Furthermore bamboo can play a role a finishing material.
Bamboo is a natural product and will therefore always have some extent of irregularity.
Bamboo can play a role as a non-supporting or finishing material.

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