Building materials account for up to two-thirds of the total cost of house construction. Moreover, the speed of construction, safety, durability, and performance of houses greatly depend on the type of building materials used and appropriate technology of construction.
Policy Imperatives
The production and availability, supply and distribution, Cost and quality of different types of building materials, particularly indigenous and traditional building materials, need to be given due attention for low-cost housing. For successful implementation of mass housing programs, a national policy for building materials is warranted. [14]
National Plan
Hitherto, the production and supply of building materials for housing has been almost entirely left to the private sector particularly in respect of indigenous materials like mud, bamboos, reeds, and local timbers
and traditional materials like burnt clay bricks, lime and stone.
Due to several constraints it has not been possible for the building materials industry in the private sector to augment its production to meet the demand. As a result there is a great demand for indigenous and traditional building materials and some materials are in short supply and their prices have risen considerably. [14]
Advance planning
To meet the requirements of construction program, the availability and production of building materials of different kinds from indigenous resources would have to be considerably stepped up. Emphasis has to be laid on increasing the production of new building materials which can be used as alternative materials
effecting saving in consumption of costly and scarce materials like cement, steel, and timber. New production units have to be installed in different parts of the country based on the latest advances in
As a matter of fact the augmentation of production of building materials required for mass housing program should be undertaken well in advance so that the required types of building materials are easily
available reasonable cost.
Inorganic Materials
Inorganic materials include commonly used materials like soils and literate, burnt clay bricks and tiles building lime and clay pozzolana, stones, and sands. As a result of research work done by CBRI,
Roorkee, India and similar research organizations in other developing countries, improved use of these materials for construction of low-cost houses has been made for achieving economy. Some of these are as given below:
1. Techniques of soil stabilization using materials such as lime, cement, and emulsified bitumen to make and walls stronger and durable, with better dimensional stability.
2. Water-resistant mud plaster using bitumen emulsion for application on soil-based walls and roofs to prevent erosion caused by rainfall.
3. Good quality late rite and lime bricks for construction of walls.
4. Better quality burnt clay bricks and tiles for construction of walls and roof.
5. Good quality building lime and clay pozzolana and also ready to-use lime and lime-pozzolana mixtures.
6. Stone spalls with cement concrete to produce economical stone blocks for masonry work. 7. Sand- lime bricks and blocks that is strong and durable. [14]
Decentralized production
In view of the locale and for different types of building materials, it is necessary to encourage the production of building materials in cottage industries as well as establish small-scale industries for production of a variety of building materials using local raw materials and skills.
It is important to improve the quality of locally produced building materials in conformity with national standards and to conserve energy required for their production. Government policies should be devised so that technical guidance as well as financial assistance is made available to motivate the manufactures to adopt improved production technology. [14]
Augmentation of conventional Materials
In the case of conventional building materials such as cement, cement concrete products, and other metallic building components such as roofing sheets, augmentation of production has to be undertaken in a planned manner. However, the cost of these materials is generally high on account of high incidence of exercise duty, sales tax, and other taxation on raw materials as well as finished products. Most of the conventional materials are so costly and sometimes scarce that they are by and large beyond the affordability of the common people and so cannot be employed for mass housing.[14]
Alternative Building materials
It is important, therefore, to search continuously for alternative building materials that are cheaper and durable. Research and development in this field needs to be supported and financed by appropriate policy. A number of indigenous and traditional building materials are in short supply. For example, there is great scarcity of timber and to prevent deforestation use of timber in construction should be either eliminated or reduced to the extent possible by use of alternative materials. Valuable agricultural soils are being used for production of burnt clay bricks and tiles as well as sun-dried bricks. These need to be conserved by use of alternative materials. Consumption of cement needs to be rationalized by use of alterative building materials such as mud, lime and clay pozzolana, gypsum binder, or rice-husk lime binders.[14]
A variety of alterative materials have been evolved, the production of which should be encouraged as a national policy by promoting the establishment of:
1. Demonstration- cum-training plants;
2. Pilot plants for introducing the production of alternative materials
3. Captive plants for production of materials by large construction departments, and
4. Commercial plants for producing alterative materials for making them available in the open market.
5. Demonstration- cum-training plants;
6. Pilot plants for introducing the production of alternative materials
7. Captive plants for production of materials by large construction departments, and
Use of Industrial and Agricultural Wastes
Due to a rapid program of industrialization as well as the green revolution in the countryside, as well as growth of cities and towns, a variety of industrial and agricultural wastes and city garbage are available in increasing quantities which not only pose the problem of disposal but also create environmental hazards.
As a result of research work done in the developing countries, industrial wastes like fly ash, cinder, red mud from aluminum plants and phosphor gypsum from fertilizer plants and be profitably used for production of a variety of building products and components. [14]
A number of agricultural waste products such as rice husk, timber waste, and grass fibers, which are available in large quantities, can be similarly used, as can city garbage such as paper waste and sludge from sewerage plants.
The national policy must not only support research to find alternative use of waste materials in construction but also support financially and technically, particularly through fiscal policies such as tax concession, the establishment of a variety of building materials industries using industrial and agricultural waste products.
Manufacture of New Materials
With the spectacular advances in science and technology, several new materials and building products and components have been developed particularly in advanced countries by the production and use of which a revolution can be brought about in the building industry and in mass housing. Financial assistance should be provided for setting up new building industries.
Policy measures
To augment the cheap production of good quality materials, the following policy measures need to be taken:
1. Provide financial support and technical guidance for expansion and modernization of the existing units and for setting up new production units.
2. Arrange timely supply of coal and other types of fuel in adequate quantity.
3. Promote adoption of more scientific methods of production, particularly to conserve energy by providing financial and other incentives.
4. Promote the production and use of alternative materials for doors, windows, rafters, purlin, roofing, and flooring to avoid or minimize the use of timber in construction.
5. Support setting up of small-scale factories for production of precast and prefabricated cement concrete components which not only save consumption of cement and steels as well as construction times but also serve as substitute materials and components for timber.
6. Establish building materials production centers in different
7. Organize a public distribution system to make available low-cost building materials. Prospects of developing new and alternative buildings materials - A case study of India
The research institutes under the council of scientific and industrial research (CSIR) viz. the central building research institute (CBRI), Roorkee, central Glass and Central Building Research Institute
(CGCRI), Calcutta, central Fuel Research institute (CFRI), Dhanbad, Structural Engineering Research centre, (SERC), Ghaziabad and Madras, National Council of Building Materials and Cement Research. Ballabhgrh, and Forest Research Institute, Dehradun over several years of research and development work have evolved a number of alternative building materials utilizing indigenous materials and industrial, agricultural and mining wastes, some o f these are described below:
Fly Ash Bricks
Over 40 million tones of fly ash is generated every year from the thermal power plants set up at various places. Processes have been developed for production of clay fly ash bricks and bricks using fly ash and
sand with addition of lime or chemicals with or without autoclaving.[14]
Sand lime Bricks
Sand lime bricks are a good substitute for burnt clay bricks with much lower energy consumption as they do not require burning but only autoclaving. Sand lime bricks have excellent structural properties and can be manufactured in a number of colors having a strength from 15 to 40 N/mm.2 As these bricks do not require clay precious agricultural land would be conserved. [14]
Cellular Concrete
Cellular concrete blocks could be a good substitute for clay bricks wherever fly ash is available. Cellular concrete is being produced in India and is used in place of clay bricks. It has good dimensional stability and the structural properties required of a building component. Because of its light weight, it is particularly suited for construction of multi-storied buildings. [14]
Late rite Blocks
Laterite soils are available in a number of place in the country especially in the western states of Karnataka, Kerala and Maharashtra. A process has been developed for the manufacture of lateritic bricks or blocks from laetrile soils using lime stabilization having strength of 70-100 kg/cm.[14]
Dry-hydrated Lime
The use of lime and lime pozzolana binder as a substitute for cement is well known. A modern, efficient process for production of dry-hydrated lime of standard quality has been developed. This dry-hydrated
lime can be used in place of cement for making mortars and plasters directl or in combination with pozzolana. It is also cheaper than cement mortar and plaster and can be produced in small-scale
units.[14]
Rice- husk Ash Pozzolana
About 12 million tons of rice husks are obtained from the rice mills in the country. It can be for the manufacture of bricks and for pozzolana binder. When rice husk is calcined under controlled conditions, the ash formed is highly reactive. In combination with lime it can be used as a binder which can replace cement in the preparation of mortars and plasters. A process has been developed for the calcinations of rice husk which is economical and can be adopted in a small scale. [14]
Hollow concrete Blocks
In places where suitable soils do not occur for manufacture of good quality bricks, cement hollow concrete blocks are manufactured and used for 2-3 storied buildings without adopting reinforced cement concrete (RCC) frame structures. These are also suitable as filler block wall construction with RCC frame for high rise buildings. The machinery for manufacturing hollow concrete blocks as well as the process are available indigenously and are being used in several places. [14]
Secondary Species of Timber
Several lesser known species of timber can be used in construction after seasoning and preservative treatment. By use of seasoned secondary species of timber the primary species can be preserved and saving of up to 30 per cent can be achieved in woodwork.[14]
Asphaltic Roofing Sheets
Asphaltic roofing sheets consist of primary board or board felt impregnated with asphaltic medium and protected with conserving material. The board is manufactured from scrap pear bagasse, jute waste and
where temperatures do not exceed 440C in the shade. They are much cheaper than traditional Asbestos cement sheets or galvanized iron sheets and can be used for low-cost housing.
Stones
In hilly regions it is a common practice to build houses with stones. Limestone, sandstone, granite, basalt, and other stones which are locally available at a cheaper rate are used in place of bricks. They are
commonly used for construction of load bearing walls. Precast stone blocks may also be manufactured, which enable the use of small stones and also reduce the thickness of walls and increase the pace of construction.[14]
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