Not Just Another Brick in the Wall

There are many premises at the basic level that have gone unquestioned for a half century. One of them is: the life of a building depends on the strength of the building material. If the soil bearing capacity of earth is 2-3 kg/sq cm. then it would seem irrational to use building materials of 300-400 kg/sq cm. The strength of the material required is the direct consequence of its surface requirement. Surface engineered building materials require serious consideration. Traditionally, a considerable amount of importance was given
to the choice of materials. This naturally ensured conservation of natural resources. The indiscriminate use of materials, regardless of location and need, leads to abuse of materials and higher cost.

BURNT CLAY BRICK
Let us look at the basic building block— the burnt clay brick. This tiny element of the building industry has for centuries been grossly misunderstood. Today, the brick is considered a building material that can be used just about anywhere for any structure. To most engineers, the sole determining factor is the crushing strength of the brick.
There are only the rare few who have questioned the need to have crushing strength that’s as high. Soil bearing capacity of most soils is a mere 2 kg / sq. cm. Why will then we use bricks that offer crushing strengths of 150 to 200 kg./ sq. cm. Is obviously open to question. It seems illogical to use material of such high strengths when the soil that the building is to rest on is of far lower crushing strength. Yes, crushing strength, up to a point, is needed as a surface engineering need. This is primarily to ensure non-erodability. Clay must be burnt adequately to meet this criterion. Suitable nonerodability is achieved when there is
Crushing strength of about 150 kg./sq. cm. If strength achieved is lower, then the brick wall would require additional surface treatment—cement plaster, for instance. In closing up the natural porosity of the brick, one is confronted with the additional problem of creating a heat trap, apart from using, unnecessarily, an expensive material. There is then the size of the brick. It is amazing that the size of a brick at 3"x4.5’x9" is uniform across the entire country. The physical aspect of clay and its content varies between regions. The size has to be modulated depending on the quality of clay that the earth yields.
The industrial age drove the need for a standard product, with technological solutions such as High Draft Kilns. This further led to consumption of coke—only worsening the fragile ecological balance. These bricks, in the past, were of excellent quality in terms of strength and surface needs. The clay of the region determined the thickness of the brick, and the final decision was that of the potter working in the area. Not so anymore. Bricks are made in one region and transported several miles for use in another area where the soil conditions have no bearing to the brick imported. While the brick is perhaps the most widely used walling component, it is also the most misunderstood. How do we establish feasible parameters for good walling elements? Walling elements do not require as much strength as is offered by these bricks. Walling
elements essentially need to be nonerodable. Low thermal conductivity is the next priority. Another factor is the extent of use of ‘processed material’. Economy, colour and texture, as intrinsic elements, are other criteria that need attention. The high benchmark of load-bearing capacity for brick was established to ensure its non-erodability—this has proved unnecessary in the context of the mass-market orientations of the present day. It is also an established fact that the denser the burnt clay brick, the greater is the strength and non-erodability achieved.
Now read this carefully: conversely, greater density of bricks increases its thermal conductivity. This results in higher internal temperatures resulting in a vicious cycle that needs expensive cooling systems. The essential criterion of a good walling material thus seems to be a non-erodable surface and a lean back-up material.
SMART SURFACE ENGG
This brings us to the critical need for intelligent surface engineering. This has to do with the creation of a permanent, nonerodable surface diaphragm composed, ideally, of reused or waste material. Integration of this diaphragm with a lean back-up material like mud or fly ash enables a walling block with a non-erodable surface and a body with low thermal conductivity. This surface diaphragm can also be made in the form of a tile with a wedge that can be integrated with the body material in the mould while casting the walling block. Tiles can be used on both sides of blocks for a permanent finish on the interior and exterior. We have fallen into the trap of using standard details the world over for foundations, walls, roofs and other elements of a building. Each successive generation of architects and builders mindlessly have adopted a static norm without rationalizing their advantages or examining alternative solutions.
THE CORE OF IT ALL
The brick is only one component. Use of reinforced steel and concrete is another. Professionals working
at the cutting edge of sustainability are proving that the bane of most conventional consulting is overdesign. Sustainable building technologies and appropriate building materials is more about rational use, and less about jeopardizing the life performance value of these materials or of design. It is obvious that there is more at stake than just simply building materials. To ensure consistent sustainable development at all levels, longterm strategies must envision processes of manufacture, that will create viable livelihoods, appropriate
technologies and appropriate materials. Once these strategies are combined with engineering parameters, building strategies will see a big change.
Prof. Anil Laul
The author can be visited at www.anangpur.com.