Use of alternate materials must be encouraged to save the environment and to reduce the cost of road construction.

Satish Chandra

= Director, CSIR-Central Road Research Institute

CRRI has always been working in the frontal areas of research in the field of highway construction and maintenance and also disseminating knowledge on new construction methods and machinery through various training programs and seminars. “CRRI has recently filed a patent on 'box pushing technology' developed by CRRI for construction of underpasses without disturbing the live traffic and various underpasses are being made by making use of this technology, states Satish Chandra, Director, CSIR-Central Road Research Institute. Excerpts from the interview…

What has been the performance of the Roads and Highways sector in the year gone by and what is your outlook for FY 2022, and what do you think the growth enablers?

Highway construction in India increased at 21.44% CAGR between FY16-17 and FY19-20. Approximately 10,855 km of highways were constructed in the last financial year, and the government has set a target of constructing 12,000 km of National Highways in the FY20. The Ministry of Road Transport and Highways hope to complete the stated target of 11,000 km of national highways (NH) by March 2021.The Government of India has allocated Rs. 111 lakh crore (US$ 1.4 trillion) under the National Infrastructure Portfolio (NIP) during 2019-25. The ministry has taken several initiatives to increase the pace of construction. The pace of construction is expected to increase further in the next financial year also. Target driven approach, support from private sectors and speedy dispute resolution are the main enables for this growth.

Post pandemic era how do you envision the transformation of design / construction processes and what contributory role CRRI playing here? 

I do not see much change in the construction process, but design of roads has changed over the time and the emphasis now is to design a thinner pavement with minimum use of natural aggregates.  CSIR-Central Road Research Institute (CSIR-CRRI) has always been in the forefront in this area. We have constructed several pilot sections in different parts of the country making use of different types of industrial wastes. We were the first to demonstrate bulk utilization of flyash in the approach road of the Nizamuddin bridge in New Delhi in early 1990s. Indian Roads congress has prepared several codes of practice for use of local materials and industrial wastes with research input from CSIR-CRRI. We are also promoting use of waste plastic, cold mix technology and recycling of pavements.

How the entire road design / construction / and maintenance ecosystem been positively impacted by disruptive technologies and digital platforms? What is CRRI's contribution here?

Disruptive technologies and digital platforms have affected all sectors and highway sector is not the exception. New technologies and state of art equipment are being used in recycling of pavements and stabilisation of layers. The stabilization of the pavement adds effectiveness to the pavement by improving its quality and reducing its thickness. Recycling is the process in which reclaimed asphalt pavement (RAP) materials are combined with new materials, sometimes along with a recycling agent, to produce hot mix asphalt mixtures. When properly designed, recycled mixtures can have better or similar performance to those of new conventional hot mix asphalt mixtures. RAP is a useful alternative to conventional methods of strengthening a pavement as it reduces the use of virgin aggregate and asphalt binder cement grouted bituminous mix is another new technology suitable for maintenance of urban roads that are prone to moisture induced damages especially during monsoon season. CRRI has taken the lead in developing guidelines for these new technologies. Our scientists are helping the field engineers in using these new technologies.

What do you think the scope for using alternate materials such as fly ash / waste plastic and marble waste in road construction?  

Fly ash has been in use for a long time in the construction of road embankments. Several thousand kilometers of roads have been constructed by making use of waste plastic. Marble dust also has potential for its use in bituminous layer as a filler material. In addition to these there are several waste materials which can be used in roads. These include iron & steel slag, construction and demolition waste, copper slag, foundry sand and many more. Use of these materials must be encouraged to save the environment and also to reduce the cost of road construction.

What are the innovative researches CRRI is excited about from its R&D for construction of flexible pavement?

There are many good research projects going on in the institute in the area of flexible pavements. Our scientists are working on development of high strength and fast curing cementitious stabilized base layer, which will reduce the curing time in field. Feasibility of using higher RAP content (50-70%)in bituminous pavements is another exciting project currently going on. The Ministry of Steel has sponsored a major research scheme of use of steel slag in road. This project is supported by several steel industries in country. We are also working on a project of making low cost equipment for construction of durable roads in Himalayan region. Porous asphalt, reinforced pavements and development of rejuvenators for recycling of pavements are other projects of high importance.

The acceptance level for smart machines for road construction - grading / compacting / and paving - is really low? What is your take on this and what contributory role CRRI can play in speeding up the adoption of such technology?

Ministry and IRC have prepared manuals for construction of 6 lane highways; 4 lane highways; and even for 2 lane highways with detailed specification and drawings. To achieve the high level of construction and riding quality of pavements, smart machines for road construction such as grading / compacting / and paving are required and are being used now. CRRI has recently filed a patent on Box pushing technology developed by CRRI for construction of underpasses without disturbing the live traffic and various underpasses are being made by making use of this technology. CRRI disseminates knowledge on new construction methods and machinery through various training programs and seminars.

How do you assess the skill set and continued upgradation of the same in the road construction sector which includes design, construction and maintenance?

Availability of skilled manpower has always been an issue and it has been flagged at several forums in the past. Concessionaires feel that fresh graduates from private engineering colleges are not suitable for direct employment. The only solution is to provide them in-house training on job specific aspects. CRRI conducts regular training programs every year for students and field engineers to make them aware of the latest developments in design, construction and maintenance of roads.

What do you think the major challenges in building up capability in this sector and what are your suggestions?

There are many challenges in highway sector. All road projects capital intensive and have long gestation periods, sometimes as long as 20 to 30 years. During this period, interest rates fluctuate frequently and unpredictably. This volatility affects the finances of the executing agency, which in turn affecting the project. Land acquisition is another major challenge and many projects are delayed due to court cases related to land acquisition. Availability of skilled and trained manpower has also been an issue. All these points must be considered by the government to boost up the sector. Land acquisition is probably the most important issue. There must be a high level empowered committee having persons from the three ministries, environment and forest, defense and road transport to clear the case of land acquisition at fast track. Job oriented training programs for fresh engineering graduates will solve the problem of trained manpower to some extent.

Please brief us on CRRI's road map to facilitate faster and sustainable road construction processes and methodologies?

CRRI has always worked in the frontal areas of research in the field of highway construction and maintenance. We have demonstrated use of several types of industrial wastes, C & D waste and waste plastic in road construction, which will lead to sustainability. Use of reinforcing materials like geogrid, geocell and geotextiles are already now part of IRC specifications. Recycling of pavements is another step towards sustainability and our scientists are educating the field engineers and concessionaires on recycling.

Design of perpetual pavements, development of fast curing materials for concrete pavements and precast concrete pavements are the areas where our scientists will be working in future.

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