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World over, recycling of asphalt pavements is a major activity, which saves natural resources. It is a green technology and saves energy. So a lot of positive effects are there in the use of RAP, but in India, people are cautious on accepting new technologies. The market for asphalt pavement recycling is at nascent stage.

According to Prof. Prithvi Singh Kandhal, Associate Director Emeritus, National Center for Asphalt Technology Auburn University, Alabama USA, recycling is one of the rehabilitation alternatives. Prof Kandhal says, ?All types of recycling methods: hot mix recycling (central plant); hot in-place recycling; cold recycling (both central plant and in-place); and full depth reclamation are available in India for implementation. The selection of the right recycling method depends on the specific project.

Unfortunately, most of our highway engineers in India lack the knowledge of pavement engineering. Crores of rupees are being spent every year on the so-called, ?Improving Ride Quality Programme? (IRQP) projects across India, where water-trapping asphalt mixes are being used which hardly last for 1-3 years.?

He further adds, ?These recycling techniques are at least 40 years old. NHAI through their circulars is only ?encouraging? recycling. Unless these technologies (especially hot mix recycling at plant) are made mandatory, India would continue to squander taxpayers? money (worth hundreds of crores of rupees per year). We can send many Mangalyaans with this money! How long will this ?encouraging? continue?? Says Abhijit Padhye, Vice President (Sales & Marketing), Linnhoff India, ?In India, the market for asphalt pavement recycling is in nascent stage. We were striving hard to convince the authorities about the benefits of using reclaimed asphalt pavement (RAP) along with the new asphalt pavement mix. Till two years back, RAP was being used in non-value added surfaces like the granular base and GSB up to 30 per cent. But now, new specifications are in place, which allow the use of RAP in the new DBM or asphalt layers. This is a major value addition for the contractor. The revised norms have added a new chapter, on the use of RAP in construction of new roads.?

Padhye adds, ?The awareness is slowly building up. Two years back, there were only 4-5 major contractors using RAP. Today, we see the numbers increased three folds as 15 leading contractors are using recycling process. And each contractor is using this at 2-3 sites simultaneously.?

Huge potential
According to Goutham Reddy, Executive Director, Ramky Infrastructure, the potential of recycling of existing asphalt pavement materials to produce new pavements is extremely high. Reddy says ?As of now asphalt pavements are being re-laid only once the original road has reached extremely bad condition. However, with BOT?s picking up and private obligations to upkeep good quality roads is increasing, we see significant increase in such recycling.?

Says Ramesh Palagiri, Managing Director and CEO, Wirtgen India, ?There is a shortage of aggregates in some parts of the country, especially in the North and East, where RAP can be a substitute. This is a major reason why we have to use RAP. However, the concept is still in its initial stages and the major challenge is to create more awareness among the consultants and the approving authorities. So we need to do more awareness activities. At least the major hurdle is cleared now with the specs in place. We are now targeting the consultants and the approving authorities and take them through the pilot projects which are happening in India and show them the results. With these steps hope we will be able to make more headway.

Blesson Varghese, Managing Director, Marini India, takes a more holistic approach. Varghese says, ?There is no way to survive without being sustainable. ?Go green or Go home?, is a very well experienced reality today, than it was ever before. Millions of tonnes of asphalt have being wasted and is still being wasted in the country, when these could be properly treated and recycled.?

He adds, ?The question today we need to address, is not just recycling it is more with durability, performance and environment. Since Indian contractors and road builders are ingenious I have seen many ingenious attempts to produce recycled asphalts on the plants. However, experience and knowledge in the field is equally important to ensure that these methods deliver durability & performance of the pavement, while fully protecting the environment. Most systems I have seen, while they solve the problem of recycling, and reclaim the aggregates, often destroy the crucial components in the hot mix, mainly Bitumen properties which dictate the performances. I am afraid, that these attempts may in future damage the technology of recycling itself, since very soon, we will see that improperly recycled materials do not perform well and / or the returns from recycling isnt quite substantial as expected.?

Varghese further adds, ?Marini users, today can easily recycle up to 35-40 per cent with minimal investment and maximum return on investment. With further investments Marini users can scale up to 50-60 per cent recycling, with the most inexpensive technology available in the market. This explains, our concern and efforts to promote sustainable development. With proven technology like DuraRAP, a Marini user can scale up his operations based on the requirements and availability of RAP and its properties. The rate of recycling is never a bottleneck for a Marini user, it is always the recycled material, which limits or allows the use of RAP.?

Advantages of recycling
Recycling of existing asphalt pavement materials to produce new pavement materials results in considerable savings of material, money, and energy. Explaining the advantages of recycling Prof. Kandhal had this to say. ?The specific benefits of recycling can be summarised as follows:

(a)substantial savings over the use of new materials
(b) conservation of natural resources
(c)performance equal or even better than new materials
(d)pavement geometrics is maintained, and
(e)saving of considerable amount of energy compared to conventional construction techniques.
The last benefit is very important due to the recent urgent need for reducing greenhouse gases that is, reducing carbon footprint thereby earning carbon credits for India.?

He explains, ?On a typical six-laning NH project, we usually bury the existing four lanes under embankment while constructing over passes or flyovers. Typically we can save about Rs 30 crore on each project. Here is an example. An existing four-lane national highway with a total length of 120 km is to be made a six-laned highway. Due to construction of over/under passes and flyovers a total of about 30 km of the existing four lanes of bituminous pavement will get buried if not reclaimed and recycled. The total tonnage of bitumen, which will be buried, is estimated to be about 7,000 tonne which has a value of more than Rs 31 crore. The total tonnage of aggregate in the bituminous pavement, which will also get buried, is estimated to be about 165,000 tonne which has a value of over 6 crore rupees. So we will have a gross savings of over Rs 37 crore. The estimated cost of cold milling and transport of RAP to hot mix plant for recycling is about Rs 8 crore. Therefore, a net savings of Rs 29 crore can be realised on this six-laning project if hot mix recycling is implemented by the NHAI by making it mandatory. There are many projects of this nature which can save us hundreds of crores. The one-time cost of modifying an asphalt batch plant to do hot mix recycling in India is only Rs 20-25 lakh.

Says Ramesh Babu Ravuri, Vice President (Tech), NCC, ?By milling the existing pavement, we can retain the final levels of the existing pavement thus saving cost of replacement/modification of kerbs, drains, crash barriers etc in highways. This also helps in urban areas to maintain the plinths of the buildings above road level. Many places, we can see that over long times the building plinths go lower than the road levels due to number of overlays in long course of time. By recycling, we can save major natural resources like aggregates, Asphalt etc. Disposal of removed asphalt pavement materials would be reduced to maximum extent thus reducing the environmental hazard.?

According to Sudhir Hoshing, CEO - Roads, Reliance Infrastructure, ?Recycling can help in reducing the material requirement which is scarce. If the stretch is big, it will also lead to cost optimisation. It is difficult to mobilise specialised equipment without having a substantial stretch of work to do. While there are advantages, due to lack of specs we haven?t yet used recycling.?

Challenges
According to Palagiri, awareness is the only challenge as of now. He says, ?For the last 3-4 years, we have worked with the government through various seminars and foreign site visits in China and the US where these projects are common and the result is the Chapter IR 37 where the hot and cold recycling are mentioned clearly and all the specs are in place. We have done a few pilot projects also for national highways - one in the Chennai-Tada project with L&T and another in Gujarat, the ITNL project on Vadodara-Halol highway. They are quite satisfied with the results and we are doing a second project for ITNL now on the same stretch. The road projects we did one-and-a-half years back are in very good condition even after the monsoon season.?

He further adds, ?We are also
working closely with institutions such as IIT Kharagpur and IIT Madras in addition to IRC. And in fact, we have provided labs to these institutes where they can do research on the reuse of RAP. Like we have done pilot projects with L&T and ITNL, many other companies have shown interest. GR Infra has purchased the first complete set of recycling equipment, both in plant and in-situ. The machines are just arrived and we will be doing the project soon. As more machines are working and more projects completed, I think more awareness will get created.?

According to Varghese, lack of vision and knowledge in the field is the main challenge to the use of RAP in the hot mix pavements. Varghese says, ?Pragmatic approach due to high pressure on investments, leads companies to be stuck with low cost - low tech equipment. This equipment however is not geared to produce quality mix with RAP and therefore recycling is not implemented in many cases and the RAP generated at job sites are simply wasted or buried in the pavements.? He adds, ?Marini has been very deeply involved with professionals in training and educating to increase awareness and to showcase the availability of proven technology. Major demonstrations to policy makers have been made to showcase the strength of our technology. Today, in order to promote this very important technology, we have also helped non-Marini users to implement recycling on their projects and to reap the benefits in terms of economic and ecology.?

Says Hoshing, ?We keep exploring these technologies to stay abreast. However, we haven?t used the same full-fledged as acceptance for such new innovations is low. IRC is still being formulated for recycling. Hence the independent engineers do not easily accept the same. Among all available technologies, hot-in-place recycling is preferred, giving cold recycling can be time consuming. Lack of specifications in IRC is the major hurdle. Without guidelines, acceptance is low. Hence, even contractors of repute do not have desired equipment for recycling.?

Says Ravuri, ?Even though, MORTH has included necessary specifications in their publications, the provisions shall be made in the contracts to enable the contractors to use the technology.? He further adds, ?Another reason for this technology not being used much may be due to high cost of machinery involved. However, as all major road equipment manufacturers are coming up with machinery required for using this technology the cost also may come down and hope this technology will flourish in near future.?

Way forward
According to Ravuri, the recycling technology will have a good future as it helps in many ways both technically and environmentally. ?We expect just like everywhere else in the world, recycling and sustainable development to pick up speed in India. The benefit with India, we foresee, is that India will be exposed to better and newer technologies and will not have to go through the learning curves in recycling technologies unlike the west,? Varghese says.

Palagiri sums it up on a high note. ?I would say the future is bright because in the next 3-5 years, the road projects will take off in a big way. And now we have shortage of aggregates on one hand and on the other hand we have the IRC 37 in place. It is the question of creating the awareness and doing more projects. Once that happens, the demand for this product will definitely increase, just like what had happened in other countries like Thailand.?