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 fibers 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

• Sizing
• Splitting
• Seasoning
• Bending
• Waterproof coating

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

• Durability
• Effect of water absorption
• Bonding strength

Comparison of Steel and Bamboo

• The strength of bamboo is greater than steel.
• Increases the strength of the buildings.
• Bamboo can crack and deflect more than steel reinforcement.
• Bamboo is easily accessible.
• Bamboo lowers the cost of construction.

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

• Low cost construction.
• It is eco friendly as it absorbs NO2 in water and CO2 in air.
• Bamboo is easily accessible.
• It withstands 7.8 Richter of seismic attack.

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.