To: RGod2 AT aol.com, homestead AT lists.ibiblio.org
Cc:
Subject: [Homestead] Architecture, building materiial, equipment a; ternatives
Date: Thu, 10 Feb 2005 16:02:18 -0500
Today, this building philosophy almost by definition, comes from India,
as does the cheapest and best tools to produce such houses.
ALTERNATIVE TECHNOLOGIES
SURFACE ENGINEERED BLOCKS(Swaran Singh Blocks)
The Swaran Singh Block is another technology developed in the series of
"surface engineering". It holds the capacity to integrate the three
basic requirements for the appropriate technology which are:
Rationalised load bearing strength
Permanent finish
Beauty and Variety
We had earlier looked into the Ram Lochan Tile, a dual casting technique
which has the composite approach to mud and stone combination. Here, we
discuss the Swaran Singh Block, an equally ingenious method. A
controlled gradation of materials is fused together and the outcome is
strong, varied and attractive external finish.
So, let's look at the construction of the Swaran Singh Block.
Construction of the Swaran Singh Block
# Take a simple, manually operated block making machine as available
with most of the Building Centres or with Institutions propagating the
use of Compressed Earth Blocks. To this add a Vibrator. The vibrator is
simply a pair of eccentric bolts attached by a pulley to a fractional
horse power motor. These machines are commonly available at most of the
Building Centres.
# Take a stiff PVC sheet or Red Mud plastic sheet cut to the size of the
base of the mould. Coat it with used mobil oil to prevent adhesion and
facilitate easy demoulding from the Surface of the block. Place the
sheet at the base of the mould. Evenly distribute stone pieces on the
PVC sheet leaving substantial gap between them so that cement mortar can
enter between these gaps. The finished face of the stone touching the
base, forms the exterior surface of the block. Here, the individual can
utilize one's sense of creativity and use stone pieces of different
colors and arrange them in patterns as may be desired for the purpose of
articulation of materials. This will open a whole new world of
expression that is offered by this simple, yet innovative technology.
# Prepare a 1: 3 mix of cement and sand mortar. Pour the mortar evenly
over the stone chips, such that it enters between the gaps for better
binding. For a short time only, switch on the Vibrator that is attached
to the Mud Block making Machine. The vibration helps integration of the
Stone pieces with the cement mortar to form an impermeable diaphragm.
Coat the sides of the Mould of the Block making machine with a layer of
stiff cement slurry. This will ensure a good surface to the mud block
for binding with the mortar when the blocks are laid in the wall and
also ensure non-erodibility to the block while curing with water.
# Prepare another mix of mud with 2% cement or 5% lime or the
combination of the two. This mix forms the major portion of the body of
the block. The mud mixture may now be put in the mould to fill 1/3 rd
volume of the mould.
# Take a jute piece little smaller than the size of the base and dip it
in cement slurry. Place the jute piece in the mould and fill the rest of
the mould with the same mix to about 2/3 rd of the mould and add another
layer of jute dipped in cement slurry.
# Now fill the mould to the top. Lock the lid and use the compressor to
compress the block. Briefly open the lid and a topping layer of 1:4
cement mortar. This layer is the pre-finish layer for the inner surface
of the wall and will require a flash coat later if at all, only to even
out the surface. Repeat the process of compaction. The jute pieces play
an important role as they bind the whole mud mix well and also allow for
easy lifting of the large mud block.
# The fabrication process is complete now. Eject the finished block and
lift it up to keep for curing. The blocks are cured for 3 to 4 days in
winters and 2 to 3 days in summers.
The process described is a gateway to creativity. This technology is
flexible in every aspect breaking away from the standardization and
universalization the modern scenario is known for.
Mould of Block
Blocks used in a building
Let's explore this added dimension of flexibility in this technology.
The block making machine itself comes in variety of sizes. Like the
Balram Block Maker has a larger version, which is suitable for the
walling units but then the blocks can be put vertical and interspersed
with bricks to form a Rat Trap Bond. The smaller version of the blocks,
can make two blocks at a time. The size is also suited for conventional
techniques of vaults and domes giving variety of colors and elegant
finishes.
There is further scope of innovation in the walling technique. Laurie
Baker's concept of 'the rat trap bond' can be introduced combining
materials such as the compressed blocks and the standard kiln fired
bricks. Major portion of the walling material is of the block and the
rest of the brick. So, instead of building a solid wall, two walls are
erected connected at regular intervals in a dowel like manner with
bricks spanning the full depth of the wall. The outer face of the two
walls is the stone surface and the inner is plain, compressed mud block.
This further economizes on the material due to the gap maintained in
between, yet achieving the regular depth of the wall. The air gap also
works as a thermal insulant and at the same time creating another unique
building pattern and leaving scope for many more adaptations.
Indian aesthetic is renowned for its richness in color, textures and
ornamentation in its entirety. This technology complements this ideology
and adapts itself in the whole system without compromise on the life
span of the building.
And how to make a really low cost engineered block---moisture
impervious, strong outside, even cheaper inner surface of block.
ALTERNATIVE TECHNOLOGIES
SURFACE ENGINEERED TILES (Ram Lochan Tiles)
Ram Lochan Tile
The Surface Engineered Block (SEB), with a thin pre-cast tile, can be
manufactured in numerous sizes and used in conjunction with diverse
materials. It combines a variety of finishes in a manner that brings out
the best of the Artist, Architect, Engineer and Artisan - a true
reflection of the spirit of Architecture.
The SEB technology is based on a simple rationale; A technology is
appropriate, in the true sense of the word, only when it can be adopted
for a variety of contexts and can use the local resources to advantage.
The SEB was developed after certain aspects of the brick were
rationalized and deconstructed as follows:
Soil bearing capacity- 2kg.
Width of foundation- approx. 5 x thickness of wall (cm) @ outset
Strength required at base of wall- 10kg/sq.cm.
Safety factor is 3 x strength required- 30kg/sq.cm.
Brick rating- 100-150kg/sq.cm.
Uniformly distributed load over a 9" wall- 1/3kg/sq.cm/floor.
As can be seen, there is a significant disparity between the performance
required of the brick and the rate of compressive strength of the brick.
Why is brick rated at 100-150kg/sq.cm? The reason for this is to ensure
non-erodibility of the exterior surface not because of load bearing
reasons. The SEB meets the criteria for walling material by
rationalizing load bearing strength, having non-erodible exterior
surfaces and adding aesthetic value to a building.
The SEB technology uses local resources, it is adaptable to a variety of
contexts, and meets actual structural and environmental requirements,
and therefore is an appropriate technology. By understanding this
rationale behind the SEB, anyone can adapt this system to different
context specific conditions.
The outer surface of the SEB is a thin tile that can be made with
different textures, colours, and materials. The tile is made with a 1:2
mix of cement and marble or stone chips that is cast into a simple mould
and de-moulded after about half an hour. (Fig. 1) After 48 hours curing
the tile is ready to be used. The tile forms the outer impermeable and
permanent surface of a SEB. The composition of the tiles backup block
can range from mud, lean concrete etc., to a mixture of flyash, gypsum
and lime. A simple mould, (Fig. 2), is used to cast the block. The wedge
in the tile ensures bonding between the tile and the backup material to
make a pre-finished walling block. The SEB can be used on site after
de-moulding and 48 hours curing.
Tile Sizes
The size of the tile can vary but must be durable so that it does not
break while being transported or during handling by the mason. The size
generally varies from 4.5"(115mm) x 9"(230mm), to 7.5"(190mm) x
15"(380mm), although smaller or larger tiles can also be made. As the
size of the tile increases the mixture has to be adequately compacted
and uniformly distributed. For this purpose, use of a hand-held vibrator
or a table vibrator becomes imperative. Corresponding to the increase in
size of the tile, its thickness will also increase.
The thickness of the tile has to be sufficient to prevent warping and
ensure non-breakage during handling. The tile thickness can vary from
¼"(6mm) to ½"(12mm) depending on the size of the tile and the size of
the chips being used. For example, a 4.5"(115mm) x 9"(230mm) tile will
require a maximum thickness of ¼"(6mm), whereas a 7.5"(190mm) x
15"(380mm) tile would require a thickness anywhere between
1/3"-2/5"(8-10mm). The size of the chips used in the mixture will also
be a determining factor in the thickness of the tile. The size of the
chips depends on local availability and the kind of aesthetic one wants
to develop. Therefore, when locally available chips are large it is more
economical to make thicker tiles, rather than spend excessive resources
trying to import chips of just the right size.
The width of the wedge should be wide enough for the mixture of cement
and chips, to be poured into the mould. The size of the chips being used
will be a determining factor in this. The wedge should be durable so
that it does not break during handling or transportation. Its depth
should be sufficient to ensure a good bond with the backup block
material. For instance, if the tile is being used with a Pre-cast
hollow-core block then its depth should be less than the thickness of
the walls of the block.
The SEB was designed keeping in mind the paradigm that a technology
should address engineering principles and simultaneously be
aesthetically pleasing and imbibe local talent. Therefore, the SEB can
accommodate a variety of finishes that can be integrated while the tile
is being cast. The mix of chips and cement, in itself, offers a variety
of alternatives. For example, granite or marble chips can be used, or
different colour pigments can be added in combination with different
coloured and various sized chips (Fig. 4). Another technique involves
fixing pieces of glass, bangles, PVC chips, or waste coloured stones
etc. on a piece of paper in a pattern. The paper is placed at the bottom
of the mould after the mix has been poured in. After the initial setting
time, the pieces stick to the tile and the paper can be gently washed
off using a wire brush.
And a funicular shell cast in place on a strippable fiberglas mold---the
shell in compression to minimize materials, maximize strength---the
ultimate design to resist earthquake and hurricanes.
ALTERNATIVE TECHNOLOGIES
FUNICULAR SHELLS
Environmental degradation witnessed today is a result of an
irresponsible use of materials. Materials are being made to perform
contrary to their natural qualities.
Most materials behave best in compression but the over reliance on RCC
has resulted in tensile structures which are made to perform contrary to
the natural qualities of the materials. For example, a conventional beam
upon loading tends to bend at the centre. The upper region of the beam
is in compression while the lower part is in tension, . To counter the
tensile stresses steel reinforcements are required in the lower portion
against its natural capabilities. Upon inverting the structure, it is
converted into a compression structure, with a considerable reduction in
the amount of steel and cement. In this case, a nominal ring beam is
capable of taking the lateral thrust developed in the structure.
Compression structures provide an alternate appropriate construction
technology which optimises the use of material and natural resources.
Traditionally compression structures in the form arches, vaults, domes,
catenaries and doubly curved structures also called funicular shells
have been used extensively in the temples / forts. These structures are
a standing proof of the durable performance of such structures that have
stood the test of time.
The funicular shell roof is one such compression structure, which
ensures conservation of natural resources by utilising waste materials
effectively and optimising the use of expensive steel and cement.
Further, the arch distributes the point load in all direction equally
thus, is able to withstand impact loading at any point.
Advantages
1. A simple yet splendid roofing system using natural materials and
technology as against the monotonous and complex conventional practices.
2. Funicular shells can take any Shape- Square, rectangle, trapezium,
triangular or any other shape. The trick lies in casting the mould.
3. The upper half of the edge beam is required to hold the stirrups
only. It is cast along with the funicular shell; therefore, it can be a
triangular section also.
4. The funicular shell can carry various conduits, toilet pipes in the
area above the brick - bat layer. These can run along the periphery
where the maximum depth is available.
5. Funicular shell roof facilitates in the installment of fixtures
likes- ceiling fans, light fixtures etc.
6. Skylight can be introduced in the roof. This can be achieved by
leaving a hollow in the fibreglass mould while casting. Since the circle
is itself very strong when used in compression, so as a hollow also it
becomes very strong.
7. The edge beam can be given a slight camber or lift in the centre,
about 1"-3". This way the beam also acts as an arch, comes under
compression, further increasing its load bearing capacity. This also
reduces the amount of steel and cement being consumed in the beam.
8. The funicular shell allows ample flexibility in design. Since the
funicular shell acts as an arch, it takes load in compression and
distributes the load equally in all direction. Thus, on the first floor,
the wall can be placed anywhere since it will always rest on the arch.
Salient Features
* A doubly curved structure on edge beam.
* Compression structure able to span square, rectangular, triangular
or orthogonal spaces.
* An attractive alternative to RCC slab for small to medium span.
* Ensures optimal utilisation of steel and cement.
* Can be demoulded every 48 hours.
http://www.dreamghar.com/faltech.html (city houses---tvoivozhd---I
dislike the Indiana Box concept---open-angles are as cheap or cheaper
than depressing 90-degree angles---I've hated these damned things ever
since college days and my weekend visits to Spring Green to talk Russian
to Olga Wright, architecture to Frank Lloyd Wright)
[Homestead] Architecture, building materiial, equipment a; ternatives,
tvoivozhd, 02/10/2005