MATERIALS FOR LOW COST HOUSING
Necessity for cost reduction
Increase in construction costs directly affects the economy. This is due to the high cost of operations which can be reduced on several levels by use of efficient Planning, cost effective technologies and materials, use of alternate techniques available, Project Management and procedures improving the procurement and dispute resolution mechanism along with the measures for initiating more competition and transparency among contractors.
The surplus gained from the saving of this surplus cost may be used for the activities such as labour welfare, implementation of modern machinery and up gradation of technologies and Construction of More Houses.
It becomes necessary to adopt the use of alternative building materials & Construction technologies due to adverse effect of using scarce resources carelessly and eventual rise in the cost of the project. However many practitioners and laymen are unaware of usage of appropriate techniques in construction. Some State Governments and Agencies of the Central Government are propagating these materials and Technologies, but the lack of precision in their specifications and absence of scheduled of Rates of these technologies, makes the construction based on these materials and technologies impossible. Many people are privately using the same, but this is not enough as till the government agencies start using them extensively, they will not be popular.
Selection of Materials
To incorporate sustainable design principles the easiest way is to select environment friendly materials. Energy conservation can be achieved through every stage of material life cycle. The Life cycle can be divided into pre-building, building and post building stage. These three stages indicate flow of building materials through different stages of a building. Pre-building stage mainly consists of manufacture which is subdivided in processing, packing and transport. The building phase mainly consists of construction, operation and maintenance whilst as the last stage would be disposal where the material can be recycled or reused.
1) In Manufacturing – Pollution prevention.
Some manufacturers carefully consider the modes of production and choose the materials which are environment friendly. These companies study and revise the methods of producing the goods to improve their quality, efficiency and reduction of waste. Selecting materials manufactured by environmentally responsible companies is encouraging them for pollution prevention.
2) Recycling of wastes in Manufacturing – The wastes which can be recycled can and used in masonries whilst as wooden wastes can be used in manufacture of plywood or soft boards. (Courtesy-BMTPC)
3) Reducing Embodied Energy and use of Natural materials – The total energy required to produce a material is called embodied energy. The energy is gained by burning of fossil fuels. The greater a materials embodied energy; it requires a greater usage of non-renewable sources. It is therefore advantageous to use materials or composite materials prepared from the wastages. The natural materials such as stones, wood, lime, sand and bamboo can be used in ample where ever possible. The natural materials impact more sustainability to structures as well as they are friendlier to environment.
4) Use of Local material – This is one of the very significant aspect of energy saving. The transport costs are heavy for the materials which are carried from long distances. Using locally available materials reduce this cost as well as the local materials are better suited to the climate conditions. In any case if the materials are to be transported, they should be transported in a small volume.
5) Energy Efficiency – Energy efficiently of a building material can be measured through various factors as its R value, shading coefficient, luminous efficiency or fuel efficiency. Energy efficient materials must reduce the amount of generated energy.
6)Use of non-toxic materials – The type of materials used, play a significant role in health of people constructing a building and people occupying the building hence to maintain a good air quality inside and outside, the selection of materials should be done with care. There are several chemicals including formaldehydes, benzene, ammonia, resins, chemicals in insulations, ply boards which are present in furnishings and building material. The health effect of these toxic materials must be considered while their selection and they must be used only where-ever required.
Higher air cycling is recommended while installation of materials having volatile organic compound such as several adhesives, paints, sealants, cleaners and so on.
7) Longitivity, durability and maintenance of a material – The materials having longer life are considered to be good for construction due to their permanence. The durable material in long term would be cost effective than the materials which need to be replaced. The lower maintenance costs naturally save a lot of building operating cost. The materials used in building determine the long term costs of an operating.
8) Recyclability and reusability – A material should be available in form which can be recyclable or reusable. Ex – the plastics waste can be used for recycling and producing newer materials. The scrap from steel can be used to manufacture the rcc bars, binding covers and other miscellaneous steel products in building construction.
9) Biodegrability –A material should be able to decompose naturally when
discarded. Natural materials or organic materials would decompose very easily. It is also a very important consideration whether a material decomposes naturally or produces some toxic gases.
Composites as Building Materials
The compositions of any two materials acting with their strength together are composites. Natural fiber materials are coming up as excellent substitutes for the prevailing building materials. Fibers likes jute, sisal coconut, ramie, banana are cheap and environmentally suited as they are made from natural fibers. They are also replacing the fiber reinforced plastics.
Composites present immense opportunities to replace traditional materials as timber, steel, aluminum and concrete in buildings. They benefit in resisting corrosion and their low weight has been proved useful in many low stress applications. Each type of composite has its own characteristic properties and thus useful for specific purpose.
Jute fiber reinforced polypropylene composites, coir fiber reinforced composites, sisal fiber and wollastonite jute pultruded composites are a few to be named. CBRI has developed MDF composite doors containing coir fiber, cashew nut, shell liquid (CNSL) as natural resin and Para formaldehyde as major constituents.
India has excellent knowledge regarding several binding factors as resins, catalysts and curing processes. It has tremendous potential of becoming a leader in composite technology with availability of several natural fibers in ample.
The composites can also be glass fiber reinforced or industrial waste based .Several prefabricated items used in building industry can be manufactured from composites. They can be used to manufacture portable toilets, water storage tanks, outdoor furniture’s, exterior claddings, interior decoration, bath tubs, basins,door and window frames, cabinets and several others.Thus the application in construction vary from cladding to internal furnishings and the owner highly benefits due to their application because of their light weight, resistance to corrosion and availability in different colours. Pultrusion is most cost effective method for producing composite profiles. It is commercially applicable for light weight corrosion free structures, electrical non conductive systems and so many other functions.
The pultruded items are recognized and recommended in the Global markets. Pultrated sections are well established alternative to steel, wood and aluminium in developed countries and catching fast in other parts of the world.