The Border Road Organisation (BRO) is planning to construct a pilot road stretch in Arunachal Pradesh using steel slag, which can withstand heavy rains and adverse climatic conditions. Creating durable roads along strategic areas could become easier if this is found to be successful.

Other Pilots

While the endeavour would be the first for the BRO, a six-lane highway made by using 100 per cent processed steel slag, to connect the port with the city, was inaugurated in Surat, Gujarat in June this year.

Slag is a by-product of steel manufacturing.

The National Highways Authority India (NHAI) will also use the steel slag for construction of a portion on Mumbai-Goa highway and the Indian Railways has also sanctioned a major research and development (R&D) project to Council of Scientific and Industrial Research (CSIR) and Central Road Research Institute (CRRI) to explore possible utilisation of steel slag aggregate as railway ballast for track construction and maintenance.

The Surat airport is also going to strengthen its airstrip using steel slag as per the International Civil Aviation Organisation (ICAO) recommendations and civil aviation requirements (CAR), according to airport authorities.

Surat Project

The one-kilometre road in Hazira, Surat has been built as part of a R&D project of the Union Ministry of Steel in collaboration with the CSIR and CRRI — a laboratory of CSIR and the government think-tank NITI Aayog.

It has been built by ArcelorMittal-Nippon Steel India (AM-NS), a leading steel manufacturer. Steel maker AM/NS India said the six-lane road was constructed using around 1 lakh tonnes of processed steel slag from its manufacturing plant in Hazira.

The project was developed with the aim to convert “waste to wealth” and has entered the India Book of Records and Asia Book of Records.

Cost Benefits

The road constructed by 100 per cent use of steel processed slag not only increases the durability but also help in reducing the cost of construction as slag-based materials are having better properties than natural aggregates.

The Indian Road Congress (IRC) guideline stipulates that for construction of a heavy traffic road, capable of taking the load of 1,000 to 1,200 trucks per day, around 600 to 700 mm thickness of road layers are required on the foundation with 8 per cent CBR (California Bearing Ratio).

According to Satish Pandey, CRRI principal scientist, in comparison to normal highways, the ones made out of steel slag are 30 per cent less thick because of better material characteristics. “The construction cost of the processed steel slag road is 30 per cent cheaper than roads built from natural aggregates,” Pandey added.

The approximate construction cost per square metre of a processed steel slag road is Rs 1,150 as against Rs 1,300 for a bitumen road and Rs 2,700 for 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.

Reducing Demand

The success of these pilot projects has great potential to reduce demand for perishable natural aggregates (stone chips and other raw materials) in road and rail projects at a time when conventional raw materials are becoming more difficult to obtain due to environmental concerns.

“Majority of steel slag after metal recovery ends as a waste dump or as land fill material and such a huge volume cannot be dumped for environmental and economic reasons. So, we have developed the customised steel slag valorisation technology to convert raw steel slag as road making aggregates,” said Pandey, who was the project leader of the steel slag road project.

India is the world’s second largest steel producing country and annually around 195 lakh tonnes of steel slag is generated and this quantity is slated to increase to 600 lakh tonne by 2030. The use of steel slag in road construction shall address the shortage of natural aggregates in the country as the production of steel slag in the country from different process routes is likely to increase from present by 2030.

Environmentally Benign

The use of processed steel slag in road construction is also expected to reduce greenhouse gas (GHG) emissions and carbon footprint in road construction activity and is in line with India’s commitment to the United Nations Sustainable Development Goal 9 to build resilient infrastructure through inclusive and sustainable industrialisation and green technologies.

The carbon footprint for steel slag roads is much lower as compared to the ones built using natural aggregates.

The natural aggregates have to be mined and processed and the material also needs to be transported from one place to another, all adding to huge carbon emission. When it comes to steel slag road, there is no blasting, drilling or crushing as the material is waste coming out of a steel industry which is processed and converted to the form of aggregate material used for construction.

Indian Road Congress

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