Review on usage of steel slag for roads

Abstract

India is the 3rd largest producer of steel with a capacity of 101 Metric Ton (MT), and this capacity is expected to grow up to 125-150 MT by 2025. The iron and steel industries generate millions of tons of various types of slag. These slags are generated during iron making and steel making processes, and are residue from these processes made of minerals like silica, alumina, and titanium from iron sand, as well as combinations of calcium and magnesium oxides. 2-4 tons of waste are generated for each ton of steel produced in different forms such as solids, liquids, and gas. The disposal of such slags is a major challenge for the steelmaking industry. With a growing availability of huge quantities of such slag materials, there is currently great focus on research to develop slag processing technologies that enable re-use of such slags in various infrastructure construction projects. The properties of the slags are very similar to the properties of natural aggregates in terms of both physical and chemical composition, and they have immense potential for extensive use in road construction and infrastructure projects as an alternative to natural aggregates. Rapid infrastructure development has led to a scarcity of natural aggregates as the demand is too high for them. These slags from the iron and steel industry are processed to make them suitable for use as natural aggregates replacements, contributing to sustainability in the construction industry. These slags can be used as an alternative to natural aggregates in sub-base, base and asphalt layers, and in concrete aggregates instead of being dumped as industrial waste near the plants. Standards, codal requirements, and suitable specifications need to be established for the large-scale use of slag continuously in construction, as well as for the implementation of large-scale recycling and re-use of slag from these industries, which can solve environmental issues in handling such industrial wastes.