“Waste steel can prove to be a more durable and cost-effective way of making roads in the future”.
Steel slag is a byproduct produced by the steel industry. Slag is created when an impurity in the form of molten flux material is allowed to accumulate in a steel furnace while it is being heated to temperatures between 1,500 and 1,600 degrees Celsius.
The molten material is thrown into the slag pits for cooling, and additional processing is done to generate stable steel slag aggregates with superior material qualities in place of the natural aggregate that is usually utilized in road projects.
During the manufacturing of steel, it is created as a byproduct in the form of a residue. The majority of modern nations have reclassified steel slag from its previous status as an industrial waste to that a material that can be helpful in building rather than one that should be disposed of as waste due to the high cost of its disposal as waste material.
After that, it is repurposed as an aggregate for the building of roads, the stability of the soil, and the base, as well as the surfacing of flexible pavement.
Why Steel Slag?
Steel slag disposal is a big issue for the steel industry because it is a waste product. The use of landfills for the disposal of waste from metal processing and metallurgical operations is particularly harmful to the environment. The aggregate produced from processed steel slag possesses a significant amount of potential for use in place of natural building materials. Steel businesses are being given a methodology to crush the steel slag into aggregate sizes that are suitable for their use.
India’s First Steel Slag Road – How was it Constructed?
The road was developed using EAF steel slag aggregates processed at the AMNS India steel mill in Hazira Surat with the help of CSIR-CRRI technological support and supervision. There has been a significant reduction in the requirement for aggregates in road construction since the country's first "steel slag road" was built in Surat. Rather than using natural stones, steel slag aggregates were used in all layers of the bituminous pavement on this section of road. The road's thickness was also decreased by 30% due to the material's increased strength.
A 1.2-kilometer-long, six-lane bituminous road was built with almost 15,000 tons of processed steel slag aggregates. The steel industry produces a significant amount of steel slag, which is a major source of solid waste. Aside from the issues of disposing of the 18.8 million tons of steel slag generated annually in India from various integrated steel plants, India is also the world's second-largest steel production.
Are these roads cost-effective and environment-friendly?
The use of processed steel slag in road construction provides the way for the environmentally responsible use of waste and minimizes the reliance on naturally occurring aggregates that can deteriorate over time. This process is also anticipated to reduce greenhouse gas emissions and the carbon footprint in road construction activity. Additionally, this process is in line with India's commitment to the United Nations Sustainable Development Goal No. 9, which is for building resilient infrastructure through inclusive and sustainable industrialization and green technologies.
A road made of processed steel slag has an approximate construction cost of 1,150 rupees per square meter, which is lower than the costs of 1,300 rupees for a bitumen road and 2,700 rupees for a road made of cement or concrete. The lifespan of a road made of cement or concrete is greater than 30 years, whereas the lifespan of a road made of bitumen and steel slag is approximately 15 years.
Do high temperatures affect these roads?
When compared to conventional ones, the upper surface of the road will be around one to two degrees warmer in temperature in the middle of the afternoon. The temperature of the road's surface has been monitored by means of a thermocouple throughout this entire process.
On the other hand, the carbon footprint of such roads is far smaller because the natural aggregates used in their construction are extracted and processed. In addition, once the material has been extracted from the ground and crushed, it must then be transported from one location to another. When it comes to steel slag road, there is no need for blasting, drilling, or crushing because the material is a waste product from a steel company that is treated and turned into the form of aggregate material that is needed for building. This eliminates the need for any of these processes. The use of discarded steel slag in the construction of roads helps to limit the amount of pollution caused by waste being deposited in the surrounding area. Additionally, the particles of steel waste are released into the air, and some of them even soak into the earth and make their way to the water table underground.
When it comes to the effect that roads like these would have on vehicles, there wouldn't be much of an influence on the tires. The melting point of steel slag is above 200 degrees Celsius, although the highest temperature recorded in India during the height of summer is only 45 degrees Celsius. In addition, the uppermost layer is constructed out of layers of bitumen.