NHAI tests doubling recycled asphalt in highway construction trial

The National Highways Authority of India has laid a one-kilometre section of the Chennai-Tirupathi National Highway using 60 per cent reclaimed and rejuvenated asphalt pavement, double the proportion currently permitted under national road codes.

Field trial on widening corridor

The demonstration was conducted on a stretch of the access-controlled highway currently being widened, using technology developed by CSIR-Central Road Research Institute that rejuvenates cold-milled material from old roads. Oriental Structural Engineers Private Limited, the contractor widening the route, partnered with Ooms India, holder of the commercial licence for the additive, and NHAI to execute the trial.

Chalumuri Ravi Sekhar, Director of CSIR-CRRI, said the rejuvenating additive restores elasticity lost by bituminous layers after years of use. Though developed two years ago, the technology had been tested only in small sections before this kilometre-long application.

Push to revise reuse limits

The Indian Roads Congress code at present allows re-use of 30 per cent reclaimed bitumen in road re-laying. Ravi Shankar, senior scientist at CSIR-CRRI, said results from the trial would be submitted to the IRC for possible incorporation into the code, enabling the higher 60 per cent threshold and preventing reclaimed material from ending up in dump yards.

"In the long run, recycling bitumen will help reduce dependency on foreign exchange," Ravi Shankar added. The additive was developed by a CSIR-CRRI team comprising Ambika Behl, senior principal scientist, Rajiv Kumar, senior scientist, and Siksha Swaroopa Kar, senior principal scientist.

Scientists from the Institute recently visited the site at Tiruvallur to verify correct implementation of the methodology and procedure. Venkatachalam, Director of the Highways Research Station, said Tamil Nadu had been reusing 30 per cent bitumen wherever feasible and would await formal IRC Code amendments before adopting the 60 per cent practice.

Source: The Hindu