Follow foot prints of developed world for utilizing wastes as construction material
By Prof. P. K. Jena
In recent years, in view of high cost of various types of construction materials for housing, roads and other essential infrastructural facilities, the developed countries in the world are utilizing most of their solid wastes generated from industrial units, mining, infrastructural facilities, agricultural and domestic sectors as alternate construction materials. In this regard, the theme of the present Indian Road Congress which was held recently in Bhubaneswar should have been identified much earlier.
Realising the importance of solid waste management from environmental and resource conservation points of view, in 1997, this author had organized an International Conference on Waste Utilization in Developing Non – Conventional Construction Materials from June 17-19, 1997 at Bhubaneswar, India. This Conference was attended by a large number of distinguished scientists and engineers from India and abroad, where some valuable recommendations were made for better utilization of solid wastes as construction materials.
Prof. (Dr). Jena in his address emphasized the use of industrial, agricultural and domestic wastes as construction materials in order to conserve the resources and protect the environment. Some of the principal wastes produced in the process of human settlements and industrial developments include domestic garbage, road and building construction and repair wastes, the overburdens of the mines, tailings, slags and solid residues of metallurgical and refractory industries and the coal ash of thermal power plants. Some of the low valued wastes like rejects of the mines, the tailings of the mineral processing plants, the wastes of demolished old buildings and roads, the incinerated domestic garbage etc. can be directly used for reclaiming low lying areas, back filling the mines and also recovering land from the sea.
Prof. (Dr). Jena in his address at the above conference while stressing the urgent need in India to utilize the solid wastes for various construction purposes, cited some typical examples where in different parts of the world the wastes are being utilized as construction materials.
1.The extension of Haneda International Airport in Japan, was reclaimed by utilizing the infrastructural construction wastes of Tokyo.
2.The incinerated domestic garbage can be utilized to reclaim land near the sea shore. He reported that, an area of 3.37 million m2 of the sea near Tokyo was reclaimed by utilizing the incinerated garbage wastes of about 31 million tons.
3.The tailings which are wastes of mineral processing industries, can be used as construction material. For example, the Canadian highway construction industries have pioneered in using tailings and slags for construction of highway. Mill tailings are very suuitable for structural components of light weight building blocks and aggregates. Manufacturing mill tailing bricks through steam curing or autoclaving process, is quite popular in the former USSR and in Holland.
4.With increasing production of iron and steel, huge quantities of slag are generated from the blast furnace during pig iron production. These slags are being used for manufacturing slag cement in dirrerent parts of the world. The utilisation of ferrous and nonferrous metal extraction slags for various construction purposes, shouuld be examined and used.
5.The utilisation of colassal amounts of ‘flyash’ generated in coal fired thermal power plants can be utilised for road making, producing fly ash bricks, as an addition material to cement, stabilization of soil etc. The examplary applicatrion of flyash pozzolanic stabilisation of soil is the construction of the runways of New York Airport. These runways were designed to support heavy aircrafts. Using flyash in mixture with sand and lime for constructing a base course of a road section of 18 km long in Santa Catarine, Brazil has been reported.
The furnace bottom ash (FBA) of the coal fired thermal power plant can be utilized along with cement for road making. Colossal amounts of red mud generated during production of alumina from bauxite can be utilized along with flyash and other such materials for back filling the mined areas. It has been possible to produce building blocks from red mud using a small amount of orthophosphoric acid as the binder followed by firing at a low temperature around 3000C.
Prof. Jena while emphasizing the urgent need to utilize various wastes generated in industrial, mining, construction and domestic sectors, has suggested that, the state and central governments should undertake some demonstration programmes so that all the solid wastes generated in the country in different sectors can be utilized as construction materials to conserve our resources and protect the environment with full cooperation and involvement of our scientists, engineers and the public.
The determination of the government, dedication of the engineers and involvement of the public will go a along way in our task for developing construction materials from the wastes and engineering the sustainable development in India. This will be another big step to achieve “Swachh Bharat”.
The author is former Director General, Council of Scientific & Industrial Research (CSIR), India.