[Homestead] Architecture, building materiial, equipment a; ternatives

tvoivozhd tvoivozd at infionline.net
Thu Feb 10 16:02:18 EST 2005


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.


http://www.dreamghar.com/faltech.html  (cube on vertex building design)


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  (free home plans---not bad 
either, this one for a farmhouse)

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)









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