“Man, whether civilized or savage, is a child
of nature – he is not the master of nature”

(Carter & Dale, 1974). IPE Global team
being aware of this fact, compiled a catalogue of eco-friendly materials that
are locally available in coastal Karnataka which can be used for the
construction of temporary structures in the beaches and islands. According to
Bromberek (2009), sustainable architecture is “creating and responsible
management of a healthy built environment based on ecological and
resource-efficient principles: environmental, technological, financial,
organizational, and social sustainability” (Bromberek, 2009). Best practice
begins with sustainability in architecture which is a constantly evolving set
of solutions. An important aspect of sustainable architecture as described by Bromberek
is passive climate control, which is healthier and more sustainable than
efforts to insulate the building and its occupants from the climate. Passive
climate control is build into the architecture and design, and includes open
floor plans, cross-ventilation, louvered ceilings, use of shade, ample windows,
the use of local materials, water, energy and waste solutions, noise control,
and numerous other features. An eco-friendly building material is one that
increases the efficiency of energy used and reduces impact on the coastal
environment. These materials have been described below.

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BAMBOO

 

Bamboo
is one of the most versatile and sustainable building material available. It
grows remarkably fast and in a wide range of climates. It is exceedingly strong
for its weight and can be used both structurally and as a finish material. Bamboo
is an extremely strong fiber with twice the compressive strength of concrete,
and roughly the same strength to weight ratio of steel in tension. In addition,
testing has shown that the shape of bamboo being a hollow tube gives it a
strength factor of 1.9 times over an equivalent
solid pole. The reason being that in a beam, the only fibers doing the work are
those in the very top (compression) and bottom (tension). The rest of the mass
is dead weight. The strongest bamboo fibers have a greater sheer resistance
than structural woods, and they take much longer to come to ultimate failure. The
enormous elasticity makes bamboo to be a very useful building material in areas
with high risk of earthquakes.

 

The
various advantages of bamboo are as follows:

·        
Light, strong and versatile

·        
Environment friendly

·        
Accessible to the poor

·        
Self-renewing resource

·        
Highly productive

 

In
its natural condition as solid culms, halved culms or as longitudinally split
strips, bamboo has been used in almost all parts of house construction except
for the fireplace and the chimneys. These are described in detail below:

 

Foundation: The use
of bamboo for foundation is rather restricted. This is mainly due to the fact that
like timber when in contact with damp ground, they deteriorate and decay very quickly
unless treated with some very effective preservatives. However, in spite of their
short life considerable use of bamboos is made as foundation or supporting
posts in case of houses built on raised platforms. The types of bamboo
foundations identified are:

 

a) Bamboo
in direct ground contact: Bamboo is placed either on the surface or buried. For
strength and stability, large diameter and thick walled sections of bamboo with
closely spaced nodes should be used. Where these are not available, smaller
sections can be tied together. It can decay within six months to two years, and
hence preservative treatment is recommended.

b) Bamboo
on rock or preformed concrete footings: where bamboo is being used for
bearings, it should be placed out of ground contact on footings of either rock
or preformed concrete. The largest and stiffest sections of bamboo should be
used.

c)
Composite bamboo/concrete columns: a concrete extension is given to a bamboo
post using a plastic tube of the same diameter. The result is a bamboo post
with an integral durable foundation.

d) Bamboo
piles: it is used to stabilize soft soils and reduce building settlement. The
treated split bamboo piles were filled with coconut coir strands wrapped with
jute. The sections were then tied with wire. After installation of the piles the
area was covered with a sandy material.

 

Flooring: The
floors may be at ground level, and therefore consists only of compacted earth, with
or without a covering of bamboo matting. The preferred solution is to raise the
floor above the ground creating a stilt type of construction. This improves
comfort and hygiene and can provide a covered storage area below the floor. The
surface of earth floor is sometimes made more stable by paving it with crude
bamboo boards made by opening and flattening whole culms. The various types
used are:

 

a) Small bamboo culms: they are directly tied
and nailed together.

b) Split bamboo: culms are split along their
length into strips, several centimeters wide.

c)
Flattened bamboo: formed by splitting green bamboo culms removing the diaphragms,
then rolling and flattening them. The resulting board is laid across the joists
and fixed by nailing or tying. They are screened with cement mortar for reasons
of hygiene and comfort as they are uneven and difficult to clean.

d) Bamboo
mats: thin strips varying in size from 5-6mm or 10-15mm and thickness of
0.6-1.2mm. These slivers are then woven into mats of different sizes according
to the available hot-press plates and user’s demands. After drying the mats to
6-10% moisture content, sufficient glue is applied to ensure enough bonding
between the overlapped areas. In construction using bamboo mats, phenolic
resins are employed.

e) Bamboo
plastic composites: it is an innovative technology in which bamboo fiber is the
raw material and compounded with plastic as the core material of the flooring.
This has higher water resistance and dimensional stability properties than
those of normal floorings.

 

Walls: The most
extensive use of bamboo in construction is for the walls and partitions. The major elements, the posts and beams,
generally constitute part or structural framework. They are to carry the self-weight of building and loads imposed by
the occupants and the weather. An infill between framing members is required to
complete the wall. The purpose of the infill is to protect against rain, wind
and animals, to offer privacy and to provide in plane bracing to ensure the
overall stability of the overall structure when subjected to horizontal forces.

 

Roofing: The roof
offers protection against extremes of weather including rain, sun and wind, and
to provide shelter, clear and usable space beneath the canopy. Above all it
must be strong enough to resist the considerable forces generated by wind and
roof coverings. In this respect, bamboo is ideal as a roofing material- it is
strong, resilient and light weighted. The bamboo structure of a roof can
comprise of purlins, rafters and trusses.

 

a) The
simplest form consists of a bamboo purlin and beams, supported on perimeter
posts. Halved culms are then laid convex side down, edge-to-edge, spanning from
the ridge to the eaves. A second layer, convex side up, is then laid to cover
the joints.

b)
Corrugated sheets made out of bamboo are also used commonly as roof covering.
The bamboo mats are dipped in resin, dried and heat pressed under pressure in a
specially made platen, to give strong, reliable sheets of bamboo, which is
lightweight. It has good insulation properties too.

c) A layer
of bitumen is sandwiched between two mats of bamboo forming a semi rigid panel.
The mats can be fixed to rafters at 200-250mm center to center. A bituminous or
rubberized weatherproof coating is then applied to the finished roof.

d)
Plastered bamboo: A cement plaster, with or without the addition of organic fibers,
is traditionally applied to bamboo roofs, to get stronger roof coverings. Various
forms of trusses are also adopted using bamboo culms of diameter ranging from
40mm-100mm. The king post trusses are the most common and the simplest.

 

The
properties as top grade building material and increased availability of bamboo
in our country makes it possible to use, bamboo in the field of construction extensively.
Its high valued utilization not only promotes the economic development, but
also saves forest resources to protect our ecological environment as a wood
substitute.

 

MUD AND CLAY

 

Mud
is especially useful in humid and hot climates. Structures
built with earth tend to be naturally cool in the summer heat and warm in cold
weather. Earthen walls change temperature slowly, so artificially raising or
lowering the temperature can use more resources than in say a wood built house,
but the heat/coolness stays longer. Clay holds heat or cold, releasing it over
a period of time like stone.

 

Given
below are the systems of building using mud and their ideal usage:

·        
COB is good for anything except height. It is
particularly good for curved or round walls.

·        
PISE OR RAMMED EARTH is strong and ideal for
solid, squat, single storey houses.

·        
ADOBE or SUN DRIED BRICKS can easily cope with
two storey houses.

·        
PRESSED BRICKS smooth and very strong and can
build three storey.

·        
WATTLE & DAUB is elegant and fine for Seismic
Zones.

 

COB

·        
With only a little water to form a very stiff
mud, a large lump is roughly moulded into the shape of a huge elongated egg.

·        
The usual size is anything between 12 to
18-inches, (30 to 40-cm) long and about 6-inches (15-cm) in diameter.

·        
A row of these cobs of mud
are laid neatly side-by-side – preferably somewhat pressed together.

·        
Then another row of cobs is laid on top.

·        
When three or four courses have been laid, one
above the other, the sides are smoothed over so that the holes and cracks
disappear.

·        
Openings for doors and windows are a problem,
which can be solved by using temporary vertical planks or shuttering.

·        
Another very simple shuttering for openings is
to use empty kerosene tins.

 

RAMMED EARTH

·        
The second method has developed from the cob
wall so as to standardize or regularize the thickness of the wall.

·        
It is also an attempt to increase the strength
of the wall by ramming it. It is known as the Rammed Earth method.

·        
Two parallel planks are held firmly apart by
metal rods and clips or bolts, or by small crosspieces of wood.

·        
Stiff mud is thrown in between these two planks
and rammed down with either a wooden or metal ramrod.

·        
When one section is completed and hard, the two
boards are moved along and the process is repeated

·        
The two planks are then raised up and a second
course of rammed earth is repeated over the first.

 

ADOBE

·        
Blocks shall be kept covered with air tight
polythene sheets for first 48 hrs with relative humidity up to 100.

·        
Polythene sheets shall be removed after 48 hrs
and the blocks shall be kept in shaded area like having enough air circulation.

·        
Sprinkle water over blocks daily, as many times
needed, during 28 days.

·        
Write date of production on block corner.

·        
Cover stacks top with coconut leaves or any
other cover to avoid direct sunlight.

·        
Principle is that blocks shall not dry for
4weeks.

 

WATTLE AND DAUB

·        
Wattle and daub method is an old and common
method of building mud structures.

·        
There bamboo and cane frame structure that
supports the roof.

·        
Mud is plastered over this mesh of bamboo cane
and straws

·        
Due to excessive rainfall the Wattle and Daub
structures gets washed off.

·        
However, the mesh of cane or split bamboo
remains intact and after the heavy rain is over the mud is plastered on again.

 

 

EARTHBAG

 

Building
with earthbags (sometimes called sandbags) is both old and new. Sandbags have
long been used, particularly by the military for creating strong, protective
barriers, or for flood control. The same reasons that make them useful for
these applications carry over to creating housing: the walls are massive and
substantial, they resist all kinds of severe weather (or even bullets and
bombs), and they can be erected simply and quickly with readily available
components. Burlap bags were traditionally used for this purpose, and they work
fine until they eventually rot. Newer polypropylene bags have superior strength
and durability, as long as they are kept away from too much sunlight.

·        
The basic construction method begins by digging
a trench.

·        
Rows of woven bags (or tubes) are filled with
available inorganic material

·        
After the foundation is laid, each successive
layer will have one or more strands of barbed wire placed on top.

·        
The weight of this earth-filled bag pushes down
on the barbed wire strands, locking the bag in place on the row below.

·        
The most popular type of bag is made of
woven polypropylene.

·        
Organic/natural materials such
as hemp, burlap or other natural-fiber bags (like “gunny
sacks”) can be used.

 

Earthbags
have the tremendous advantage of providing either thermal mass or insulation,
depending on what the bags are filled with. When filled with soil they provide
thermal mass, but when filled with lighter weight materials, such as crushed
volcanic stone, perlite, vermiculite, or rice hulls, they provide insulation. Earthbags
can be stacked in a wide variety of shapes, including domes, hence they have
the potential to virtually eliminate the need for common tensile materials in
the structure, especially the wood and steel often used for roofs. This not
only saves more energy (and pollution), but also helps save our forests, which
are increasingly necessary for sequestering carbon.

The Table
below shows the comparison of Concrete with natural materials in terms of
various properties:

PROPERTIES

BAMBOO

CONCRETE
BLOCKS

MUD BLOCKS
(COMPRESSED)

Structural

Works better with moisture in shear forces; have
high flexibility than steel and lower young’s modulus

Can be given strength as per required; less mortar
joint as size bigger which increases stability

Economic and energy efficient

Thermal

Excellent

Excellent

Excellent

Temperature
and water resistance

Moderate

Excellent

Excellent

Buildability

Moderate

Excellent

Excellent

Cost (In Rs/sq.
m)

Depends on thickness

31.25

15.625

 

 

LATERITE STONE

Laterite
Stone is a natural product which is abundantly available in the coastal regions
of Karnataka and this makes it suitable for modern day eco-friendly
constructions.

The color and texture along with firm and
physically resistant nature of laterite stone make it to be useful in many
ways.

 

 

Laterite
Stone Pavement Blocks

These
paving blocks are the alternative for the concrete interlocks. The
concrete stones exhaust heat whereas laterite paving blocks won’t emit
heat.

Laterite
Stone Partition Blocks

These
stones can be used for partitioning the cabins, which can make the cabins more
spacious and chill.

 

Laterite
Stone Wall Blocks

These
stones are used for constructing buildings instead of bricks and other stones.
When these stones are used, plastering and painting can be avoided and the
stones very strong. 

 

Salient
Features of Laterite Stones:

1)
 Purely natural product.
2)  Highly eco-friendly and heat resistant.
3)  No chemicals are being used at any time during manufacturing.
4)  Cement motor or plastering is not needed while laying walls.
5)  Wall partition as low thickness blocks which provide room more
spacious.
6)  Various thickness blocks are available.

 

LIFE
EXTENDED THATCH ROOFING

Thatch
roofs can withstand high winds and heavy rains, provide good thermal insulation
and are easy to repair. Thatch is light, needs only a simple support structure and
is flexible so can be used for any roof shape. It is self-help, locally
available and environmentally sound option. By treating it with copper sulphate
solution, its life can be lengthened to reduce biodegradability effect. By
using thatch in the form of compact panels instead of bunches, its
combustibility is also reduced. Additional coating of treatment on the roof
surface using phosphorylated spray or CNSL oil also achieves water proofing,
fire resistance, termite proofing and weathering resistance.

 

COCONUT FIBRE AND WOODEN CHIPS ROOFING SHEETS

Coconut fiber
and wooden chips or fiber are soaked in water for two hours and water drained
off .Later these are mixed with cement and laid over a corrugated mold and kept
under pressure for 8 to 10 hours. After demolding, these are cured and dried
before use.

 

 

 

 

 

 

 

 

CORRUGATED BAMBOO ROOFING SHEET

An innovative roofing material with an upgradation
of traditional material from Bamboo Board. It is eco-friendly, lightweight,
strong and durable and minimal fire hazard compared to thatch and other
materials. These sheets can be used for roofing, walling, door and window
shutters and other components in building construction. Sheets are bonded with
phenol formaldehyde resin to which anti-termite chemical is added at the time
of mat impregnation. These are termite resistant and fire retardant.

 

Main
Advantages:

·        
Bamboo roofing sheets are environmentally
friendly and a safe alternative to plastic, zinc or corrugated asbestos roofing
panels.

·        
They have the same standard measurements as
conventional corrugated roofing sheets.

·        
Bamboo roofs are quieter in the rain and cooler
in the sun than conventional metal or plastic sheets. A study has shown that
cows in sheds roofed with bamboo yield more milk than those under corrugated
zinc sheets because of the cooler environment.

·        
Bamboo sheets are durable and strong with
excellent internal bond strengths and a high resistance to weathering, fire or
insect attacks.

·        
They have an attractive and natural appearance
and are easy to work with (cutting, drilling)

 

                            

 

 

 

 

REFERENCES

 

 

·        
Eco-Tourism Resorts: A Case Study of Best
Practices at the Hamanasi Resort in Belize, Kathryn Early, University of New
Hampshire

·        
Environment Friendly Indian Building Materials
for Cost-Effective Housing, Society for Excellence in Habitat Development New
Delhi

·        
Prospects of Low Cost Housing in India, Swaptik
Chowdhury, Sangeeta Roy School of Mechanical and Building Sciences, VIT
University, Vellore, India Email: [email protected], [email protected]

·        
Bamboo as a Building Material, P. Sharma1, K.
Dhanwantri2 and S. Mehta3 Amity School of Architecture and Planning, Amity
University Haryana Manesar, Gurgaon, Haryana, India.

 

 

 

 

 

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