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  • 10/9/2023


Why in news?

Recently, India has developed the world's latest Steel Slag Road Technology, which allows for large-scale utilisation of waste slag from steel plants for road construction, according to Jitendra Singh, Union Minister of State (independent charge), Science and Technology.

What is Steel Slag Road Technology?

  • The technology has been developed by the CSRI under a research project in collaboration with the Ministry of Steel, Government of India and four major steel manufacturing companies of the country, viz., ArcelorMittal Nippon Steel, JSW Steel, Tata Steel and Rashtriya Ispat Nigam.
  • This technology facilitates the large-scale utilisation of waste steel slag in steel plants and has proved very useful in the effective disposal of about 19 million tonnes of steel slag generated in the country.
  • The advantages of steel slag roads. Not only are they approximately 30 per cent cheaper than conventional paving, but they are also more resilient and resistant to unpredictable weather conditions.
  • In June of last year, Surat in Gujarat became the first city in India to have a processed steel slag road constructed. This was made possible through a joint-venture project involving the CSIR-CRRI, the Union Ministry of Steel, NITI Aayog, and Arcelor-Mittal Nippon Steel at Hazira.
  • About one lakh tonne of steel slag aggregate has been used in its construction. No natural ballast of any kind has been used in the construction of this road.
  • The first road made with steel slag road interpretation technology has become famous for its technological excellence at the national and international levels.
  • Despite being 30 per cent shallower than roads paved with natural aggregates, the experimental stretch of a six-lane road paved with slag has proven to be highly resistant to weather and heavy truck traffic.
  • The second steel slag road was constructed at NH-33 Jamshedpur, and the third steel slag road was completed at NH-66 Mumbai to Goa Highway in Maharashtra.
  • The National Highways Authority of India (NHAI) has also successfully used this technology in road construction on National Highway-66 (Mumbai-Goa) in collaboration with JSW Steel, under the technical guidance of CRRI.

How Steel slag road is different from regular road?

  • To construct a heavy-traffic road capable of withstanding the load of 1,000 to 1,200 trucks per day, the Indian Road Congress guidelines recommend a road thickness of around 600 to 700 mm on a foundation with eight per cent CBR (California Bearing Ratio).
  • However, roads made from steel slag can be 30 per cent thinner due to their superior material characteristics.
  • Additionally, the construction costs of these steel slag roads are approximately 30 per cent cheaper. The Hazira road, for example, utilises around one lakh tons of processed steel slag.
  • According to B R Bhatt, Engineer at SMC's Road Development Department, "the approximate construction cost per square metre of a processed steel slag road is Rs 1,150 as opposed to Rs 1,300 for a bitumen road and Rs 2,700 for a cement or concrete road.
  • Because of its inherent high strength and stiffness, steel slag bituminous surfacing will provide a more lasting heavy load road surface in the face of harsh weather conditions in hilly regions.

Are these roads cost-effective and good for the environment?

  • Surat Municipal Corporation (SMC) Road Development department officials say the utilisation of processed steel slag in road construction paves the way for sustainable use of waste and reduces the reliance on perishable natural aggregates.
  • This process is also expected to reduce GHG emissions and carbon footprint in road construction activity and is in line with India’s commitment to the United Nations Sustainable Development Goal No. 9 for building resilient infrastructure through inclusive and sustainable industrialization and green technologies.
  • This new technological approach also addresses the issue of environmental degradation caused by waste steel slag and unsustainable natural aggregate mining and quarrying.
  • The approximate construction cost per square meter of a processed steel slag road is Rs 1,150 as against Rs 1,300 for a bitumen road and Rs 2,700 for a cement or a concrete one.
  • The lifespan of a cement or concrete road is over 30 years while that of bitumen and steel slag road is around 15 years.

Scope for India

  • The abundance of steel slag generated as a byproduct of India's steel industry presents a significant scope for the country.
  • Being recognised as the world's second-largest steel producer, India currently produces around 19 million tons of steel slag annually, and this is expected to increase to 60 million tons by 2030.
  • With approximately 200 kg of slag generated for every tonne of steel production, finding efficient disposal methods for steel slag is crucial to mitigate environmental challenges.
  • One of the major issues is the accumulation of large heaps of steel slag around steel plants, causing water, air, and land pollution.
  • To address this problem, the Steel Ministry is collaborating with the Ministry of Science and Technology and the Ministry of Road Transport and Highways to explore the potential of steel slag road technology across the country.
  • By utilising steel slag in road construction, India can turn this waste into a valuable resource and address both environmental and infrastructural concerns.
  • Steel slag road technology has shown promise as a cost-effective and durable alternative to traditional materials like bituminous concrete, making it an attractive option for building resilient roads.
  • The scope for India lies in actively promoting the use of steel slag in various applications, particularly in road construction, which not only helps manage the waste but also contributes to greener and cleaner infrastructure development.