The National Highway Authority of India (NHAI) is encouraging the use of waste materials for road construction intending to reduce the carbon footprint. The move is in line with the government’s commitment to use waste material for construction of National Highway Infrastructure in the country, abiding with the Indian government’s ‘Waste to Wealth’ mission. The use of innovative road materials that incorporate recycled or renewable resources can help reduce the environmental impact of road construction. These materials can minimize the consumption of non-renewable resources, decrease carbon emissions, and promote a more sustainable approach to infrastructure development.
To promote the use of innovative road materials, the NHAI is collaborating with research institutions, industry experts, and material suppliers to identify and test promising materials. Demonstrating the performance and benefits of innovative materials are being projected as pilot projects.
Different types of waste materials used for road construction
Steel slag for road construction
In line with the union government’s ‘Waste to Wealth’ mission and encouraging environmentally sustainable national highway construction, a trial use of ‘steel slag’ in road construction has been initiated by NHAI. Steel slag, a by-product of steelmaking, is produced during the separation of the molten steel from impurities in steel-making furnaces. This initiative will help address the challenge of shortage of material used in development of the national highways and could replace natural aggregates such as sand, gravel, or crushed stone with the waste material from the steel industry.
India’s first Pavement Quality Concrete (PQC) with steel slag
To construct India’s first Pavement Quality Concrete (PQC) with steel slag, the National Highways Authority of India (NHAI) started trials for its possible use in road construction.The authority permitted Central Road Research Institute (CRRI) to construct a 1-km-long trial patch in the Raigarh district, for PQC of the Panvel-Indapur section of NH-66 near Mumbai, where 100 percent natural aggregates were replaced by steel slag-derived aggregates. The results from the trial are said to have been encouraging.
India’s first cement concrete steel slag road soon in Maharashtra
Maharashtra will get the country’s first cement concrete steel slag road on National Highway 66. This road is being built using steel slag (industrial waste) along with cement slag. A brainchild of Central Road Research Institute (CRRI), NITI Ayog and the Council of Scientific & Industrial Research (CSIR). This technology is being termed as a cheaper, more durable and environment friendly way of building roads.
The road is being built around 50 kilometers away from Mumbai near JSW steel plant in Dolvi. 1 km road has been constructed and the work is in progress. A similar technology was used in Surat for a bituminous road, but this is a cement concrete road.
Construction of NH 32 with steel slag
Over 1.2 million tonnes of slag-based aggregates have been utilized in the construction of the National Highway (NH)-33. The four-lane, 44.2 Km long stretch from Saherbera to Mahulia section of NH33 was developed by National Highways Authority of India (NHAI). This stretch of road is constructed using steel slag manufactured by Tata Steel. In March 2023, the highway was inaugurated by Minister of Road Transport and Highways (MoRTH), Nitin Gadkari.
Phosphor-gypsum for road construction
NHAI along with the Department of Fertilizers, Ministry of Chemicals & Fertilizers is taking up field trials on NHAI projects for use of Phosphor-Gypsum in National Highway construction to achieve a circular economy in the use of Gypsum.
Phosphor-Gypsum is a by-product of fertilizer production. An Indian fertilizer company has constructed a road using Phosphor-Gypsum. The road was evaluated by Central Road Research Institute (CRRI) and based on their report, the Indian Road Congress (IRC) has accredited neutralized Phosphor-Gypsum waste material for road construction for a period of three years.
The fertilizer company and CRRI have been asked to take up field trials on an NHAI project to evaluate performance of Phosphor-Gypsum on a National Highway and to generate confidence among various stakeholders on use of Phosphor-Gypsum waste material in Highway construction.
Fly ash and Plastic waste in road construction:
The NHAI authorities have already used ‘Fly Ash’ in the road construction project and in building flyover embankments. Around 1.2 crore cubic meters of fly ash have been used in the construction of a 125 km long six-lane ‘Eastern Peripheral Expressway.
Waste plastic has already been tested very successfully. Studies have established that roads built using plastic waste are durable, and sustainable and increase the life of the bitumen. In February 2023, in its effort to increase the use of plastic waste in road construction, the road transport and highways ministry made the use of the waste material in hot mix bituminous wearing coat or top layer mandatory on all service and slip roads throughout the National Highway (NH) network in the country.
Bio bitumen for road construction
Apart from the above-mentioned materials Shri Nithin Gdhari has been focused on the implementation of bio bitumen for road construction projects. Speaking at the FE CFO Awards in May 2023, Union Minister Nitin Gadkari stressed on the use of bitumen in the construction of road projects. “The burning of rice straw or ‘parali’ is a big problem for pollution in Delhi and adjoining areas. Indian Oil has already started the conversion of rice straw to bio bitumen in its plant at Haryana’s Panipat.” He further added that market demand of the bitumen is around 80 lakh tonnes of which refinery capacity is 50 lakh tonnes. 30 lakh tonnes has to be procured from the farmers. “
With the increased scope of road construction, the road sector is focusing its attention on alternative construction materials and ensuring sustainable and quality output. To meet the government’s goal of carbon emissions reduction by 1 billion tonnes by 2030, green construction materials are being adopted. The Ministry of Road Transport and Highways (MoRTH) has been instrumental in advocating and promoting the use of sustainable practices.
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