Studies on Use of Ferro Chrome Slag for Replacement of Aggregate in Road Construction
Posted: 21 Jun 2019
Date Written: June 15, 2019
The greatest user of natural resources is the rapid developing sector of the construction industry. This raises very important concerns on the depleting of these resources at an alarming rate which causes serious threats to the environmental balance. Rapidly depleting deposits of good quality aggregates and ever increasing demand, emanating from infrastructure construction activities has led towards unsustainable quarrying of natural aggregates. Need of the hour is to explore feasibility of replacement of natural aggregate with alternative sustainable material.
The large scale industrialization has resulted accumulation of huge amount of by products or industrial waste, endangering the environment in terms of land, air and water pollution. The sustainability of industries now depends upon the effective management and utilization of its byproducts. In order to use the industrial waste in huge quantities efforts are being made to use the same as a substitute of natural resources. Ferrochrome slag is the by-product of waste generated from the ferrochrome steel plant. Rate of ferrochromium slag production is 1.1 to 1.5 times that of ferrochrome metal produced. Global ferrochromium slag production is around 12 to 16 million tons per year.
Majority of ferrochromium slag is discarded and sent for land filling which will create a huge waste deposit over the years. Many researchers addressed the oxidation of Cr (+3) to Cr (+6) in presence of strong oxidants in laboratory conditions and there exists a controversy regarding the possibility of slowly releasing of Cr (+6) to environment in long run term practice. Therefore profitable utilization of these wastes in an environmentally safe manner is still a challenge for the ferrochrome producers.
Concerted efforts are therefore needed to explore the possibility of using ferro chrome slag in other sectors to solve the disposal problem. Road construction is one such sector where huge quantities of waste materials could be gainfully used. Detailed investigations are therefore, necessary to investigate the utilization of ferro chrome slag in roads.
This paper brings out the details of laboratory investigations carried out to find out suitability of ferro chrome slag as alternate road construction material. Bituminous samples using both ferrochromium slags and natural aggregates were prepared to determine their physical, mechanical, chemical properties through laboratory testing. Toxicity leachability test was also conducted on the slags to determine whether they posed any detrimental effects on the environment.
The results indicate that the physical and mechanical properties of ferrochromium slag are as good as those of natural aggregates. It can be used as a base or sub-base material in highway pavements and as also alternative aggregate in bituminous material. Furthermore, the use of the slag as aggregate in pavement layers reduces the requirement for natural aggregates and saves the existing natural resources.
Keywords: ferrochrome slag, road, leaching
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