The double-barrel innovation is totally driven by customer need as well as the need of authorities. It actually delivers significant improvements in energy, carbon emission and the total cost of pavement making. The superior performance sustained over the years by this great innovation makes it a preferred choice for the customers in many countries and it has replaced the conventional plants, says Somnath Bhattacharjee, President, MHS & EPS Business ? TIL. In an exclusive interview with Equipment India, Bhattacharjee throws light on various issues and the future potential of using RAP. Excerpts from the interview.

Given the quantum of road construction projects, how do you assess the potential for the usage of RAP and other advanced mixes?
We are optimistic about the future of RAP usage in India. This is primarily due to the fact that demand for infrastructure and high quality road is critical for the India growth story. So far only two per cent of the road network has been built as expressways. The quality of roads dictates the economy of a country and thence, the quality of our lives. In India more than 60 per cent of the freight and more than 80 per cent of the passenger traffic move on roads. Roads are vital for the transport of goods and passengers. Going forward, the focus is going to continue on infrastructure and the government will need to prioritise on the same to sustain a strong GDP growth. In the next five years, approximately $60 billion will be invested to build 35,000 km of roads. The roads that are being built now will be ready for maintenance and rehabilitation in the next five to ten years.

With growing concern about environmental protection and sustainability of natural resources; using double-barrel and RAP technology will be a necessity in the years to come. There will be various government agencies and construction companies adopting successful green technologies which will include extensive use of RAP, warm mix and combining the use of RAP in warm mix, etc.

The generation of RAP is expected to be substantial in the near future due to road-widening and maintenance projects and consequently, judicious use of the same is a must. Research has shown that combining WMA and RAP offers potential improvements in pavement performance compared to using either separately. Recycling of existing asphalt pavement materials for making new pavements result in considerable savings of material, money and energy.

On the policy front, how do you view the steps initiated by the government in reducing the carbon footprint of road construction and in promoting sustainable asphalt pavements?
We are moving in the right direction. MoRTH, IRC, CRRI, NHAI and other agencies have initiated steps by encouraging recycling of existing asphalt in order to reduce carbon emission in the road construction activity besides significant benefit in total cost and energy saving. The use of RAP has been made mandatory by NHAI and the Flexible Pavement Committee of IRC is working on formulating a standard specification for usage of RAP. Even CRRI is studying the use of warm mix and the future for these sustainable technologies look positive.

However, the initiatives of the government agencies need to be supported by adequate training and awareness generation on project implementation by the authorities, independent engineers and the like, to ensure quick buy- in and implementation.

Has there been any study done by TIL in India to find the cost savings per km of road constructed, using RAP with double-barrel technology?
Double-barrel technology with its sequential mixing technology, offers a unique value proposition to the users. The production of homogenous mix using RAP has been the highlight of the double-barrel technology. The cost- effectiveness has come about by the use of RAP where the recovery of both bitumen and aggregate has been the key element. Estimates of saving potential could be as high as approximately 400/tonne of hot mix asphalt.

Over the last two years , TIL has worked with the customers extensively on various projects and has been able to demonstrate sufficient cost savings using double-barrel technology maximising usage of RAP, besides reducing the carbon emission significantly in those projects.

To what extent can energy be saved and pollutants reduced by using RAP and other advanced mixes?
Depending upon the type of fuel used for producing the hot mix / warm mix, the reduction in energy can be as high as 21 per cent through usage of advanced technologies like double-barrel; a correspondingly significant reduction in carbon emission is also achieved.

What is the contribution of double-barrel technology here? How environmentally-friendly is this technology?
Globally the road construction authorities and the contractors have been considering cost-effective methods to design, build and maintain road infrastructure.

The double-barrel innovation is totally driven by customer need as well as the need of authorities. It actually delivers significant improvement in energy, carbon emission and total cost of pavement making. The superior performance sustained over the years by this great innovation makes it the preferred choice for customers in many countries and has replaced the conventional plants.

The double-barrel with its RAP -friendly technology offers significant benefits to the customer and also leaves a lower carbon footprint.

The ability to produce warm mix asphalt (WMA) using bitumen foaming technology popularly known as `Double Barrel Green System` is a vital offering to the road construction industry. The WMA foaming system is presently the industry benchmark for producing warm mix asphalt and is a giant step forward for the industry because it uses water as an additive to produce warm mix asphalt. It allows road construction companies to produce warm mix material that is equal to hot mix material in performance, while requiring less fuel for drying and thereby generating lower emissions. Double-barrel green makes the production of sustainable WMA a reality.

Has this been used in many road projects?
There are two TIL-Astec installations of double- barrel plants in India and they are being used in the following road projects:-
? 6-laning of Nellore Chilkaluripet - Nellore Section of NH-5 from km 1,182.802 to 1,366.547 (length 183.620 km) in Andhra Pradesh under NHDP Phase V being executed by BSCPL Infrastructure Limited and
? 4- laning of Rohtak-Bawal section of NH-71 in Haryana ? EPC contract being executed by Varaha Infra Limited.

The double-barrel technology is a result of intensive research done by ASTEC Inc on road construction techniques, the voice of the customer, the need of a sustainable road construction methodology and most importantly , conserving the environment.

To what extent does the double- barrel technology differ from drum mix plants?
Double-barrel is a combination aggregate dryer and mixing unit separated from each other and uses sequential mixing to produce larger volumes of consistent and homogeneous hot mix in a shorter time than any other plant. It is equipped to provide multiple job mixes at very short notice.

Also the features like automatic aggregate gradation unit, dual- fuel modulating burners, infrared sensors to maintain heating of aggregate at specified temperature, ability to handle larger dust/ exhaust volumes, ease of operation and maintenance, ability to run up to 50 per cent RAP without any visible emission, the fuel efficiency the plant offers, the ability of the plant to produce consistent asphalt mix, and option to produce warm mix asphalt with foamed bitumen, act as cutting edge differentiators in
the industry.

The TIL ASTEC double- barrel hot mix asphalt plant brings to the customer a very cost- effective method of construction of bituminous pavements. The use of the RAP helps the customer recover a hundred per cent of the aggregate and the residual bitumen in the RAP. The savings is substantial for the customer with no compromise on the quality of the mix.

There is a view that batch type plants are far better equipped for the advanced mixes than drum type plants, and it is understood that NHAI has not accepted the use of drum type plants. What is your take on this?
Irrespective of the technology - batch / continuous, inefficiencies can and do pull profitability down. If a technology is successful globally, there is no reason why India cannot adopt it. Global road construction companies are here in India and they are going to adopt best practices to keep their cost down without any compromise on quality.

A double-barrel drum mix plant is ideally suited for hot mix asphalt recycling. The shell of the drum is used as the shaft of the coater. The virgin aggregate is dried in the inner drum and superheated to 315-340 C (when recycling about 50 per cent RAP). It then drops through the wall of the drum and meets the RAP in the annular space. Since the outer shell does not rotate, easy access is available to add virgin asphalt binder and/or rejuvenating agents. In this method, the RAP material is not exposed to the hot gases.

MoRTH and NHAI have accorded their approvals for the double-barrel hot mix plant. There is no comparison between double- barrel technology and a conventional drum mix plant and the differentiator is the use of RAP and the ability to produce a homogenous mix. The success of double barrel technology globally is a classic example of the evolution of the drum mix technology.

The homogeneous mix will eventually decide the quality and durability of the road surface.

Brief us on why these concepts have still not caught up here with the road contracting fraternity?
The awareness of the usage of RAP is limited to a few in the road construction companies in India. The organisations realise they are sitting on black gold but the knowledge to use the RAP is still at a nascent stage. Although the payback is quicker due to competitive total cost of ownership, the acquisition cost of technology is perceived to be higher.

At TIL, we have entered into a licensee agreement with ASTEC Inc to manufacture double-barrel plants in India which will eventually improve the delivery lead time of the plants. The use of the RAP will help customers to recover a hundred per cent of the aggregate and the residual bitumen in the RAP. The savings in operational cost will be substantial for the customer with no compromise on the quality of the mix. Eventually, the advantage in total cost of ownership will mitigate the perception of higher initial cost.

We are convinced that the use of RAP will be quite predominant in the road construction industry in India, and TIL ASTEC double- barrel hot mix plant will prove to be a cost-effective solution for customers.

Constant training and building awareness on recycling of hot mix will also be a key enabler for faster adaptation to this cost-effective, advanced technology.

We are actively engaging with the regulatory authorities, consultants and construction companies to build awareness and capability of effective recycling of hot mix.

How constructive are our codes and specs in terms of propagating the use of RAP and other advanced mixes?
MoRTH and NHAI have been strongly advocating the use of RAP. However, the awareness of the comprehensive benefits of RAP usage is still low. Globally, many countries have adopted the use of RAP consistently and have gone way ahead in terms of percentage usage of RAP used in the hot mix asphalt.

Tell us about the steps initiated by TIL for training of operators and technicians.
Training is a very important aspect as the trained operators can only deliver desired result from high performance products in ensuring high uptime and best performance from the equipment. Skill development in our customers? organisation is a key priority for us. We have built a state-of-the-art manufacturing facility at Kharagpur, West Bengal, and constant support from ASTEC has enabled us to impart the right training modules for building capability in customers? organisations.

The interface between academicians, respective government bodies, OEMs and the contracting fraternity seems to be weak. Has TIL initiated any steps to improve matters?
We are deeply engaged with government bodies, academicians and the contracting fraternity, sharing ASTEC?s rich wealth of global experience and best practices with these organisations. We clearly see a move in the industry towards harmonising with the best global practices for building high quality and durable roads in India.