PROPERTY PLUS

Strong, stylish, long-lasting

There are nearly two million bamboo artisans fading away in the country — and we have little awareness of how best to use the material. Experts say bamboo can replace 70 per cent of the steel and wood used in construction. Its use in buildings can bring down the cost by 40 per cent, says architect Neelam Manjunath, perhaps the only designer in the construction world to be spearheading the cause of bamboo, especially in structural applications.

Bangalore-based Neelam, who heads the Centre for Green Building Materials & Technology and is associated with the Bamboo Society of India, has handled nearly 100 projects in 15 years that use bamboo profusely. “It is one of the fastest-growing plants on earth and easy to harvest,” she says. Bamboo makes up about 13 per cent of the total forest area, with 40 per cent of the world’s bamboo forests in India. We shred a portion for paper pulp, but not for construction.

Bamboo grass is packed with power, derived from its axial fibres. The elastic vascular bundles in its stalks offer high tensile strength that’s comparable to steel, tough enough for ‘steel reinforced concrete’ to be replaced with ‘bamboo reinforced concrete.’ It is an ideal material to withstand earthquakes when built with proper connection techniques.

Neelam uses bamboo in walls, beams, columns, doors, windows, thatched roof, railings, grills, pergolas, fencing, bridging, staircase, boundary wall and furniture. It can be used as composites in various industries, apart from bamboo lumber being useful in corrugated roofings, partitions, veneers, ply, and bamboo block floorings.

Fighting ignorance

So, why is there so much hesitation in using the green gold? The British sidelined bamboo as the ‘poor man’s timber’, says Neelam. We had hundreds of bamboo structures in India built with abundant traditional wisdom, but the Britishers changed them to wood. In Assam, many houses built with bamboo a century ago still stand safe. Hundreds of houses in and around Devanahalli in Bangalore (beyond Tipu Sultan’s Fort) have bamboo mat horizontals running below a lime-surki roof slab and they stay strong even after 75 years.

Neelam Manjunath, who has bagged several international awards for her research in the field, built the pantry building of the Raj Bhavan in Bangalore with bamboo and bamboo composites. “A 100-year-old building had to be re-made. Apart from walling and counter top, we used corrugated sheets of bamboo for roofing along with waste from the same construction spot. The work was over in less than a month, and the building was inaugurated in January 2000,” she says.

The material is ideal for light-weight roofing for large span structures. The false ceiling at the Madrid Airport, created by British architect Richard Rogers, uses bamboo composite strips, making it naturally fire-proof, says Neelam. Bamboo has natural cellulose and silica, which makes it physically incombustible. Bamboo can also be used for foundation piling in coastal areas where steel tends to rust.

Bamboo allows for speedy construction as well, since most of the work can be completed off-site. Pre-fabrication is one of the star points of the material, which can go into wall panels, doors, partitions and roof structures.

Neelam specialises in using concrete with bamboo fibres, instead of the usual plastic fibres, as an additive for better bonding with concrete — as its hygroscopic properties can make it a challenging factor in the drying process.

Research



“A shell-roof or free-form roof of 7” thickness can easily develop cracks when concrete bonding is not attended to. But being light and flexible, bamboo is good for efficient structures. Research is on in India and China for the effective use of bamboo reinforcement in high-rise structures,” she says.

Since bamboo is bio-degradable, avoid letting it get in contact with soil. And use of chemical treatment procedures such as boric acid and borax powder are a must to make it termite proof. Inter-nodal injections too are critical for long health, while finishes using protective coating like paint, enamel, laminate or polish can be used with great effect.



1

Bamboo can replace 70% of steel and wood used in construction. And can reduce costs by 40%




2

Bamboo's high tensile strength is comparable to steel; tough enough to make ‘bamboo reinforced concrete’




3

Bamboo can be used in walls, beams, columns, doors, windows, roofs, railings, pergolas, staircase and boundary walls