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 The
Auroville Visitors and Reception Centre is a popular and pleasant
place for the use of visitors and Aurovilians alike. It was constructed
in 1988 with grants from HUDCO and the Foundation for World Education,
and has become well-known for its architecture and energy-saving
construction materials. In the Society section of our site you will
find a descriptive page on the daily comings and goings of this
buzzing place, while the following article by its architect and
builder concentrates on the more technical details of this remarkable
building.
The Auroville Experiment
Using compressed earth blocks
As the main purpose of the Auroville Information
and Reception Centre is to introduce the international township
to visitors, the Auroville Building Centre (AVBC) has taken the
opportunity to demonstrate and promote the rich potential of alternative
technologies in its construction, with particular emphasis on the
use of mud as a building material. An information office, conference
room, exhibition space, video room, restaurant, handicrafts shop
and toilets were accommodated in a structure specifically designed
for visitors from all over the world, with the local climate materials
and building skills influencing the design. Special emphasis was
placed on natural lighting and ventilation in the building, as renewable
energy sources were to be used. The AVBC wanted to limit the use
of concrete and steel, but this was easier said than done, for in
a compression structure the construction of arches, vaults and domes
is necessitated. Prefabricated ferrocement elements were used for
all doors and overhangs, thereby doing away with the use of wood.
A 4m grid using load-bearing pillars and arched or corbelled openings
was made with stabilised compressed earth blocks to reduce costs.
Solar, wind and biomass energy, water management and recycling techniques,
mud and ferrocement technology, and reclamation and afforestation
were all integrated in the process. Stabilised soil blocks for domes
and prefabricated ferrocement channels were considered as the best
solution to roofing. It was felt the resulting sequence of arcaded
and semi-covered spaces would give a clear sense of direction to
people.
 As
1.6 lakhs blocks were to be made for this and future projects, AVBC
employed a number of special tools for their specific needs - standard
wheelbarrows to transport soil, flat wheelbarrows to transport the
blocks, metal sieves of various mesh sizes, steel centring for arches,
compasses for constructing domes, and a new improved Auram 3000
press to compress the earth blocks. This press was specially designed
for higher output, with many unique features, as the Astrams acquired
only manufactured 30.5x14.5x10cm blocks when ¾-and ½-sized blocks
were needed for bonding and thinner blocks of the same size, 30.5x14.5x5cm,
for the domes.
Granite block foundations and earth block structures
A composite type of foundation in stabilised
mud mortar was used because of its advantages. The material to be
used had to essentially have a greater load bearing capacity than
the stabilised blocks. Thus the use of fired bricks was eliminated
and locally mined rough granite blocks were used instead. This foundation
was cheaper and less time consuming than the conventional fired
brick foundation, and most of it could be done using unskilled labour.
The excavations for pillar foundations were always made up to the
clay and gravel strata, which varied between 75cm and 120cm below
ground level.
The plinth surface was evened with a normal cement plaster bed and
then given a primer of bitumen and kerosene followed by a layer
of hot bitumen as a damp-proof course and anti-termite barrier.
This was not a complete success as the pillars, pushed outwards
by the loading of arches and domes, started sliding out over the
bitumen layer. This was corrected by drilling holes in the horizontal
plane at the base of the pillars and anchoring them with steel bars
to the granite plinth. For best results in earth building a clear
understanding of the available soil is imperative, and some basic
characteristics of grain size distribution, Atterberg limits (liquid
limit, plasticity index, shrinkage limits) and procure are to be
analysed.
At the start of the project, the Auroville soil
laboratory was not yet available, and no lab analyses were done,
only a number of tests were conducted with various soil-sand-cement
mixes with the two different soils available on the site - a gravelly
soil and a yellow sandy soil. The two parameters of need -the cost
factor quality and the type- as well as the two parameters of specific
project requirements -including quality and cost factors- plus the
actual product behaviour in terms of dry and wet compressive strength,
water absorption, quality of surface and edges, led to the choice
of the optimum mixes.
The test results indicated the eventual manufacture of two types
of compressed earth blocks with 5 and 4 percent cement content by
weight in the following mixes:
The 5 percent blocks, 95 percent by weight of soil constituting
1/5 gravely soil 4/5 yellow sandy soil. 5 percent by weight of cement,
11 percent moisture content and 4 percent blocks, 96 percent by
weight of yellow sandy soil, 4 percent by weight of cement, 11 percent
moisture content.
The 5 percent blocks were used for the first floor pillars and all
other walls.
INTERVIEW
Architect Suhasini Ayer (S.A.) in conversation with Anupama Kundoo
(A.K.)
S.A. I was introduced to earth as a building
material in urban areas by HUDCO's conference in Trivandrum. I had
seen pictures of earth buildings in Rajasthan, Yemen and Morocco
which were very beautiful, but it had never been introduced as a
relevant possibility in most architectural colleges. Today, after
trying to understand and use the material, after experiencing the
usual drawbacks and frustrations, I can say that mud is the most
responsive of building materials, and even its limitations are exploitable
for a more human and relevant architecture and urban environment.
We felt the need to reintroduce earth in a way that would appeal
to the aspirations of the local people, who at present want fired
brick and concrete houses because according to them that is what
all public buildings and houses of rich people are built of. Earth
construction, which is ancient, has to also answer a contemporary
need taking into account the vernacular.
A.K. Having built your own house with
adobe, why did you choose soil blocks for the Information Centre?
S.A. I personally believe that adobe
is the most economical material, and is suitable to the available
labour resource, but one has to go through the stages of transfer
of technology so that it is not rejected by the prevalent prejudice
against adobe or kuccha bricks.
The compressed stabilised block has the right
impact of technology to interest the layman, as it enhances the
strength (making large openings possible), aesthetics, precision
and facility for building. Psychologically, the public feels secure
with this technique as the structure will not erode during a chance
rain.
A.K. What were the formative principles
of design?
S.A. When one uses minimum steel and
concrete and stabilised compressed blocks, one goes back to the
age old solutions of arches, vault and domes. We have tried using
these features to give a more contemporary interpretation, with
an eye to achieve maximum floor space. The building follows the
same principles as a beam and column structure, except that the
beams are arches and the columns are brick pillars. This way, we
could have flexibility in the floor plan, large openings and maximum
usable floor space.
Adapted from an article by Anupama Kundoo, Architect,
Auroville
Published in 'Indian Architect & Builder', December 1991
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