The Alternatives Methods for Road Construction

               The Alternatives Methods for Road Construction 

The Indian Roads Congress (IRC) released the Rural Road Specification Code, 2014, detailing how to use locally available material such as jute, coir and waste such as fly ash, plastic rubbish, paper mill sludge and construction and demolition debris in laying rural roads. IRC is a subsidiary body of the Union Ministry of Road Transport and Highways that sets design and material specifications for roads and bridges.

The need for such a code stems from the fact that rural roads are typically paved with bitumen or concrete. But use of bitumen has adverse impact on environment.

For each kilometre of traditionally constructed road, tonnes of crushed stone, gravel and sand, together called aggregates, concrete and bitumen are needed, leaving the diesel required for powering the construction equipment. This is an expensive affair, particularly for India which needs to construct more than 0.2 million kilometres of rural roads and maintain another 0.3 million km to meet its vision for providing a road to each habitation by 2025.

Role of Road in Rural Economy

“Rural roads help farmers transport agricultural produce to local markets and provide easy access to educational, healthcare and financial institutions. They are crucial in strengthening local economy and improving the quality of life of those who live in villages. As state governments are responsible for laying rural roads, their abysmal performance prompted the Centre to launch the Pradhan Mantri Gram Sadak Yojana (PMGSY) in 2000 for all weather road network in rural area. MoRD implements the programme as part of its initiative to connect rural India with roads.

Use of aggregates and bitumen can do irreparable damage to the environment. Both bitumen and aggregates are non-renewable minerals. And mining of sand, gravel and crushed stone remains largely unchecked. They are the most mined minerals in the country and constant head-ache of MoEF.

Alternative Methods of Road Construction

Spread jute and coir, make roads stronger

Road Made of Coir

10% cheaper than conventional roads; lasts 6-7 years

Every soil has a different capacity to withstand the load of vehicular and pedestrian traffic. Engineers use different technologies to reinforce soil’s load-bearing capacity. Typically, engineers strip the topsoil, pave the track with layers of aggregate as per traffic load, and seal it with bitumen. But all roads need not have high load-bearing capacity. In rural roads a thin layer of aggregates covered with geo-textiles—woven fabrics, such as jute and coir mats, that are used to strengthen the soil—serve just right.

In 1934, jute was reportedly used to make the Strand Road in Kolkata. “But the trials were not followed up and the potential of jute in road construction remained unexplored for long..

Jute geotextile serves another purpose of PMGSY: strengthening rural economy. According to the National Jute Board, more than 4.5 million people depend on the jute sector for a living. “Larger use of jute geotextile would help retain this large work force. “There are jute mills in West Bengal, Assam, Bihar, Tripura and Andhra Pradesh. All of eastern and north-eastern states, Madhya Pradesh and a good part of the southern states can easily procure jute geotextile from these mills for paving their rural roads.

Rural roads in coastal areas can be built using another geotextile—coir mats. Use of coir in paving rural roads can generate 10,000 employment opportunities in cottage industries.

As an added advantage, the lifespan of roads increases by three to four years. This cuts down the maintenance cost.

How about a plastic road?

Plastic Road

10-18% cheaper; lasts 15 years

The idea lies in exploiting the texture and water-resistant nature of plastic to construct roads. First, plastic wastes are segregated, cleaned and shredded to the size of 2-4 mm. It is then heated and coated over gravel. The laminated gravel is then mixed with bitumen to lay roads.

The technology significantly increases the strength and life span of roads as compared to conventional bitumen roads. “The reduced consumption of bitumen makes plastic roads cheaper, but they prove to be further cheaper, say by 10-18 per cent, in the long run as they do not require maintenance for at least 15 years. Besides, the technology provides a way to dispose of non-degradable plastic waste. One kilometre plastic road can consume one tonne of plastic waste. On an average, each individual in the country uses seven kg of plastic carry bags a year.

Use fly ash in road, save soil and cement

20% cheaper; lasts 6-7 years

Fly ash, a waste produced by thermal power plants, can be used in place of soil to construct roads. This would help save 20-30 million tonnes of fertile top soil used in widening roads and raising its levels every year.

Besides, ash ponds created to dump fly ash occupy thousands of hectares and contaminate the top soil. These ponds also host stagnant rainwater and wastewater, leading to serious health problems among people living in the vicinity.

 Fly ash can be used as a soil stabiliser. It acquires the property of cement after it is mixed with lime. The technology also increases the life span of roads by about 15 years.

Roads made from demolition waste

10-15% cheaper; lasts 5-6 years

Developed countries, including the US, the UK, France and Japan, use waste materials generated during construction, renovation and demolition of buildings as aggregates in laying roads. “These wastes are a mix of concrete, tiles, bricks and other construction materials and can be partially used as replacement of 35 per cent of aggregates in laying rural roads.

Recycling and re-utilisation is an important strategy for management of such waste. This would also help reduce the demand-supply gap for aggregates, conserving depleting resources.

Use cold-mix technology, lay roads round the year

10% cheaper; lasts 5-6 years

As the name suggests, cold-mix technology does not involve heating the bitumen. Instead, it uses bitumen emulsions, prepared by mixing bitumen with water. The slurry is then poured over the aggregates.

The biggest advantage of the cold mix technology is that it helps save precious diesel, used in heating bitumen while laying conventional roads. “On an average, this technology helps save about 1,500 litres of diesel per km. It also aids faster black-topping of roads. Besides, unlike conventional roads, which are built only during the summer months, bitumen emulsion can be applied over damp aggregates and can be used to build roads around the year. This type of road is particularly suitable for north-eastern India that receives spells of rain over a longer period. Assam has constructed nearly 1,700 km of rural road in the past two years by using bitumen emulsion.