Ir. Patrick C AUGUSTINFIEM, PEng, FICE, CEng, FIStructE Perunding FAISAL, ABRAHAM dan AUGUSTIN sdn. bhd.No. 20-3 Jalan 28/70A, Desa Sri Hartamas, 50480 Kuala Lumpur, MALAYSIA

BAMBOO REINFORCED CONCRETE – FERROCEMENT LIKE CONSTRUCTION

IntroductionBamboo is a group of perennial evergreens of the grass family found in abundance in the wild and as a cultivated plant.

It is one the fastest growing plant and used as a construction material and also as a food source. As a construction material it is used for construction of houses, scaffolding and laminated to form parquet flooring. Bamboo shoots before they grow into clums are harvested as a food source. They are poisonous before cooking.

An early study of bamboo (1) for use as a substitute for reinforcement has rules that were similar to reinforced concrete design, mimicking main reinforcement bars and stirrups arrangements. The modulus of elasticity of bamboo and its allowable tensile strength ( 27.5N/sqmm) were assigned low values. Bond strength of bamboo in concrete was observed to be low. Recent research shows that bamboo have much higher tensile strengths (3) and better mechanical properties..

When bamboo is dried and used in concrete wall construction (2) it capacity to resist punching loads was in a ductile manner. Panels of 1mx1mx70mm could resist at least 320kg punching load.

The death toll in the recent earthquakes in Sumatra, Haiti and other tropical and sub-tropical regions was most often caused by collapse of masonry walls used in load bearing mode and as infill to reinforced concrete frames.

It is proposed that bamboo used in ferrocement like mode in is a viable alternative for construction of housing in the form of prefabricated panels or logs. Packing narrow ( 10mm ) bamboo strips in a sand cement mortar binder will result in reduction in density of the finished product. The only high energy content in this form of construction would be in the cement used.

Bamboo Clum (7)

Bamboo is hollow with spherical partitions between nodes. The nodes are the raised points on the body. Generally bamboo grows in dense clums in the wild. In cultivated plantations, the shoots are transplanted to ensure that clums can grow uniformly.

The multitude uses of bamboo include walls and floors of houses, furniture, musical instruments, laminates for flooring and high quality charcoal much favoured by the Chinese, Japanese and Koreans.

Fig 1

Mechanical Properties of Bamboo

Ref 6 Age of Clum (yr)

Average Wall Thickness (mm)

Moisture Content %

Density (gm/cc )

Tensile Strength ( MPa)

Compressive Strength (MPa)

Shear Strength ( Mpa )

Bending Strength ( Mpa )

Bending Elastic Modulus ( Mpa )

3 – 4 3 8 0.72-0.91 140-207 63-79 6.7-6.9 89-194 9629-20890

Ref 9 148-384 62-93 20 76-276 20000

The tensile strength varies when tested between nodes and across the nodes. It is weakest across the nodes.

When bamboo is used directly in beams as longitudinal and shear reinforcement, the disadvantage of low bond strength can be overcome by treating the surface. If chemicals are needed, it increases the cost of construction. A form of construction is needed that does not require high bond strength and relies on the tensile attributes of bamboo.

Over reinforcement in the member can overcomes the short comings of poor bonding when a suitable form of construction is chosen. A dense matrix of bamboo strips within a cement mortar binder would be ideal.

Intensive Use of Labour In after earthquake incidences ( Haiti ) , the use of intensive labour in construction assist in the rehabilitation of communities by providing employment. The use of bamboo as reinforcement in concrete road pavement (8) employs the communities directly from setting up plantations, harvesting bamboo, cutting and fabrication and putting it in place.

Since bamboo is fast growing it can also be used in combating soil erosion is areas where there has been lost forest or vegetation cover.

Investigation of The Behaviour of Ferrocement Type of Bamboo Reinforced LogsTwo sample planks were made each 90mmx180mmx600mm were made in a backyard, reinforced with several layers of split bamboo in the long direction only. The bamboo was obtained from a drain reserve that has been growing abundantly. The first sample was constructed using neat cement grout and the second sample with sand cement ( 1:3) mortar.

When the samples had been cured for 28 days they were then cut along the long axis to provide specimens for beam flexure test and crushing samples by further cutting the half of each split plank into more pieces. The samples that had been tested in flexure were also further trimmed and cut to obtain additional samples for crushing.

Fig 2 Bamboo Reinforced Log After Casting Fig 3 Bamboo Reinforced Log After Cutting

Typical Sample Division – Sand Cement Mortar Log

Beam Flexure 90mm x 100mm x 650mm

Crushing Cube (1)

98 x 92 x 101

Crushing Beam ( 7 ) 98 x 91 x 250

Crushing Beam (8 ) 97 x 100 x 250

Upon completion of flexure test , the good ends were trimmed to obtain 3 more good specimens for crushing, Cubes 2, 3 & 4.

Typical Sample Division – Neat Cement Log

Beam Flexure 90mm x 90mm x 650mm

Crushing Cube (5)

95 x 95 x 97

Crushing Beam (9 ) 93 x 94x 250

Crushing Beam (10 ) 91 x 95x 240

Upon completion of flexure test , the good end of the neat cement mortar beam was trimmed to obtain 1 good specimen for crushing, Specimens 6.

Test ResultsThe effective flexure strength of the neat cement and sand cement bamboo reinforced logs was 6.11N/sqmm and 10.13N/sqmm respectively. The beams were test by 2 point load arrangement , with a span of 450mm.

The failure mode of the neat cement log was a delamination type of failure along the bamboo reinforcement extending back to the support.

Fig 4 Neat Cement Mortar Bamboo Reinforced Log

Fig 5 Sand Cement Bamboo Reinforced Log – Pullout Failure

The failure mode of the sand cement log could not have been more different. At failure a single large crack was visible at the center of the beam. Additional load was applied to see how the beam would completely rupture.

The was clearly a slip failure at the bamboo concrete interface.

Crushing Strength Results ( N/sqmm )

Specimen Composition Strength

1 1:3 Sand Cement 26.58

2 1:3 Sand Cement 20.04

3 1:3 Sand Cement 21.31

4 1:3 Sand Cement 22.57

5 Neat Cement 9.22

6 Neat Cement 12.98

7 1:3 Sand Cement 28.22

8 1:3 Sand Cement 12.27

9 Neat Cement 12.09

10 Neat Cement 11.57

Specimen 8 failed prematurely when a bamboo strip close to the surface initiated a delamination mode of failure.

Discussion of ResultsBamboo ferrocement type reinforced logs made of sand cement (1:3) mortar has high compressive strength. It has sufficient compressive strength to be self supporting as a load bearing wall panel as its strength in compression exceeds the requirements of single and double storey dwellings by several times..

The high tensile strength of bamboo contributes significantly to the flexure strength of the material. This becomes significant when ductility and high impact strength is required in earthquake zones.

The construction does not require special skills to manufacture wall panels or logs for new construction.

It significantly reduces cost as bamboo is a fast growing plant that is found in the wild and allows itself to be cultivated as plantation crop as opposed to steel reinforcement that has to be manufactured with high energy inputs.

The labour intensive nature of it production permits employment on-site labour found in disaster areas.

The flexural strength can permit it to be used as suspended precast floors of moderate spans of 3-4m.

Robust housing resistant to earthquakes can be constructed with this material.

1) BAMBOO REINFORCED CONCRETE CONSTRUCTION , February 1966 U. S. NAVAL CIVIL ENGINEERING LABAORATORY, Port Hueneme, California ,Francis E. Brink and Paul J. Rush

2) Bamboo Reinforced Concrete Wall as a Replacement to Brick and Mud Wall , Dr D Maity, S K Behera, M Mishra, S Majumdar cirica 1988

3) Bamboo as reinforcement in structural concrete elements , Khosrow Ghavami , Department of Civil Engineering, Pontificia Universidade Catolica, PUC-Rio, Rua Marques de Sa˜ o Vicente 225, 22453-900 Rio de Janeiro, BrazilReceived 26 September 2003; accepted 4 June 2004 4) Designing and Building with Bamboo , Jules J.A. Janssen, Technical University of Eindhoven, Eindhoven, The Netherlands

5) Durability analysis of bamboo as concrete reinforcement, Humberto C. Lima Jr. Æ Fabio L. Willrich Æ Normando P. Barbosa Æ Maxer A. Rosa Æ, Bruna S. Cunha 2007

6) Mechanical and Physico-Chemical Properties of Bamboos carried out by Aerospace Engineering Department, Indian Institute of Technology – Bombay with Prof. NK Naik as Principal Investigator Cirica 2003

7) http://en.wikipedia.org/wiki/Bamboo

8) BAMBOO REINFORCED CONCRETE PAVEMENT ROAD CONSTRUCTION IN CAMBODIAby Mustafa I. Azam , Samer Al-Fayadh, Fergus Gleeson & Robert Petts Part 2 Draft June 2002 9) Deformation of Embankment on Bamboo Reinforced Soft Clay , TAN Shi Yong , University Technology Malaysia 2009-2010