The use of industrial waste as construction materials has been catching the attention of engineers especially in view of the emerging problems caused by their disposal and the pollution caused by them and also in the need to conserve natural resources.Some of the industrial wastes and their use as a construction material is described below.

Fly ash is a waste in the form of fine residue from thermal power plants which we use pulverized coal as the fuel.It is a highly effective Pozzolonic material and can be beneficially utilized in the following applications

♦ Lime fly ash mortars

♦ Fly ash calcium silicate bricks

♦ Manufacture of cellular concrete

♦ Manufacture of Pozzolonic  cement

♦Stabilized bases for roads

Modification of Portland cement by addition of industrial wastes

Additives like fly ash,blast furnace slag and lime are used in the manufacture of blended cements namely pozzolona cement ,slag cement and masonry cement respectively.Addition of fly ash result in saving up of about 20% of Portland cement and 50-80% of blast furnace slag containing slag cements saves large.

      Gypsum wastes from ammonium fertilizer and fluorine plants have been found suitable for blending with slag cement to produce supersulphated cement which has high resistance to sulphate bearing soils and water.Byproducts gypsum from phosphoric acid plants that is phospho gypsum can be utilized for manufacturing gypsum blocks for internal partition walls.They have good insulating properties but cannot withstand moist conditions as in exterior masonry walls.

        Waste lime sludge from sugar paper or carbide acetylene gas industries can be successfully used for blending with normal Portland cement for making mortars.These waste lime sludges have also been used for small scale manufacturing of cement.

         Up to 30% of spoil production is used as a fill material in road construction in European countries .Effort are being made for the utilization in brick making and manufacturing of light weight aggregates and secondary fuel.Blast furnace slag  are being portably used in the air cooled slags,for making dense aggregates for roads and for concrete walls,foamed light weight aggregate for light weight concrete,granulated variety for cement manufacture of slag bricks and autoclaved blocks.

        Fired fly ash brick, fly ash concrete,and oil palmed shell aggregate concrete are some other modern materials are utilized from industrial wastes