It is possible to make concrete using agro , urban , and industrial waste materials .The economy depends on the cost of handling,processing and transportation .The stability and durability of the products developed with waste material over the expected life span is of utmost importance , mainly in relation to building and structural application .
The waste material included in this catagory are of plant origin - sawdust,coconut pith rice husk and others . Natural organic waste materials are used to make light weight concrete , before using on a large scale as constituen in concrete for building and other construction , careful design for the structural properties and durability need to be carried out .
URBAN WASTE or INORGANIC WASTE
Huge quantities of building rubble becomes available each year durin the demolishion of old structure to make new one due to rapid urbanisation . Usually broken concrete , broken bricks and crushed glass used to produce concrete of requisite strength and durability . Dumping of these materials causes pollution of environment .
The broken rubble is recycled i.e. the process of removal of durt,reinforcement,plaster or gypsum from thm the old crushed concrete. Broken concrete and broken bricks recycled concrete is suitable for base or sub-base for pavements , and it reduces the construction cost by 30 %. These can be designed to obtain the required strength to use in foundation,flooring and walkways in a light building .
Some of the industrial by-product wastes can be profitably used in the concrete construction industry . Some of the by-products are Blast furnace Slag , Coal Ash, Red Mud Aggregate ( by-product from the production of alumina from bauxite ) , Silica-fume . All these wastes used to make cement ultimately reduces cost of concrete .