CSIR-Central Road Research Institute (CSIR-CRRI), Oriental Structural Engineers Private Limited (OSEPL) and Ooms Polymer Modified Bitumen Pvt. Ltd. (Ooms India) have demonstrated the use of 60% Reclaimed Asphalt Pavement (RAP) in the Dense Bituminous Macadam (DBM) layer of National Highway-716, Chennai-Tirupati Package-I.
The field demonstration was carried out to test high-RAP recycling technology under actual highway construction conditions. Senior officials from the National Highways Authority of India (NHAI) and the Government of Tamil Nadu, along with representatives of highway infrastructure companies, technical experts and other industry stakeholders, attended the programme.
The demonstration covered the complete recycling process, starting from RAP recovery and processing to material characterisation, rejuvenation, mix design, hot-mix plant production, laying and field compaction. Participants also visited the hot-mix plant and an Experience Centre showcasing how reclaimed asphalt is recovered, processed and reused in new pavement construction.
RAP contains aggregates and aged bitumen that can be recovered, assessed, rejuvenated and reused. Using a higher proportion of RAP can reduce the requirement for virgin aggregates and bitumen while making use of material already available in existing roads.
At the 60% RAP level demonstrated on NH-716, a substantial share of the material required for the new asphalt mix comes from the existing pavement. The approach can help conserve natural resources, reduce dependence on virgin and imported raw materials, minimise construction waste and lower the environmental impact associated with highway construction.
60% RAP: Turning Existing Roads into a Resource Bank
Reclaimed Asphalt Pavement contains valuable aggregates and aged bitumen that can be scientifically recovered, characterised, rejuvenated and reused. Higher utilisation of RAP can reduce the requirement for virgin aggregates and bitumen while making productive use of materials already available within the existing road network.
60% RAP Demonstration on NH-716 Showcases Circular Approach to Road Construction
Reclaimed Asphalt Pavement (RAP) contains aggregates and aged bitumen that can be recovered, characterised, rejuvenated and reused through scientific processes. Greater use of RAP can reduce the need for virgin aggregates and bitumen while putting materials already available in existing roads back into productive use.
The 60% RAP demonstration on National Highway-716 showed that a substantial share of the material required for a new asphalt mix can be sourced from the existing pavement. The approach can help conserve natural resources, reduce dependence on virgin and imported raw materials, minimise construction waste and lower the environmental impact of highway construction.
The demonstration also presents existing highways as a potential “resource bank” for future road construction, supporting a more circular and resource-efficient approach to infrastructure development.
REJUBIT Technology Used for RAP Rejuvenation
A key part of the demonstration was REJUBIT, an indigenous RAP rejuvenator jointly developed by CSIR-Central Road Research Institute (CSIR-CRRI) and Ooms India. The technology is designed to restore important properties of aged bitumen contained in reclaimed asphalt, enabling a higher proportion of existing pavement material to be used in new asphalt mixes.
The application of REJUBIT on NH-716 takes the technology beyond laboratory development and into field-scale highway construction.
Speaking at the event, Dr. Chalumuri Ravi Sekhar, Director, CSIR-CRRI, said RAP should not be considered merely as waste, but as an engineering resource containing valuable aggregate and bitumen that can be recovered, rejuvenated and reused.
He said the field demonstration brought together the complete recycling chain, covering RAP recovery and characterisation, scientific mix design, rejuvenation, hot-mix production, laying and compaction under actual field conditions. Such demonstrations, he added, are important for developing field knowledge, building confidence and establishing a scientific basis for greater use of reclaimed materials in road construction.
Dr. Ambika Behl (F.I.E.), Senior Principal Scientist, CSIR-CRRI and Project Leader of the 60% RAP Field Demonstration, described RAP as “black gold for the road sector”, pointing out that it contains two valuable non-renewable resources, aggregate and bitumen, already present in the existing road network.
She said higher levels of recycling require proper RAP characterisation, evaluation of aged binder, scientific mix design, suitable rejuvenation and rigorous quality control. According to her, the use of REJUBIT provides a practical route for increasing the reuse of existing road materials while reducing consumption of virgin resources.
OSEPL and Ooms India Support Field Trial
The field trial was undertaken jointly by Oriental Structural Engineers Private Limited (OSEPL), CSIR-CRRI and Ooms India, bringing together highway construction expertise, research capabilities and RAP rejuvenation technology.
Mr. Nagaraj, Sr. CPM (Project Head), OSEPL, said an innovative pavement technology needs to move beyond laboratory design to plant production and actual highway construction. The 60% RAP trial, he said, provides an opportunity to assess high-RAP construction at field scale while maintaining the required quality-control framework.
Mr. Palash Kathal, Director, Ooms India, said higher RAP utilisation allows greater value to be recovered from the aggregates and bitumen already present in existing pavements and can reduce dependence on virgin materials. He described taking the 60% RAP mix through laboratory evaluation, plant production and live highway laying as a significant technical milestone.
Tamil Nadu Highway Research Station Welcomes Demonstration
The Chief Guest, Sh. Er. A. Venkatachalam, Director, Highway Research Station, Chennai, congratulated the participating organisations on the successful field demonstration and described it as an important milestone for Tamil Nadu in moving towards more sustainable and resource-efficient road construction.
He pointed to the state’s extensive road network as offering considerable scope for recovering and recycling materials from existing pavements. Such reuse can reduce the requirement for virgin aggregates and bitumen as well as construction waste.
He also expressed confidence that the demonstration would generate useful field experience and help support the wider adoption of high-RAP recycling in suitable road projects across Tamil Nadu.
About the NH-716 Trial
The 60% RAP trial section on NH-716 was executed under the technical guidance of CSIR-CRRI. Dr. Ambika Behl, Scientist F, CSIR-CRRI, led the project, while Dr. Rajiv Kumar, Scientist E1, CSIR-CRRI, was involved in the design and construction of the trial section along with teams from Ooms India and OSEPL.
The initiative is intended to generate technical and field-level experience with higher RAP utilisation and contribute to the evidence required for its responsible and wider adoption in Indian highway construction.
The successful demonstration shows the potential of recycling technologies to convert pavement materials from waste into engineering resources. It also brings together research institutions, highway contractors and technology providers in developing a more resource-efficient approach to road construction.
