Researchers at IIT Hyderabad developed a new material, asphalt pavement (RAP), which have low cost, environmental friendly, and possess more strength than asphalt roads.
The new material is made of a mix of fly ash (a coal-combustion by-product) with reclaimed asphalt concrete. The team reported their findings in the journal Construction and Building Materials and Journal of Materials in Civil Engineering. The martial reduces the consumption of virgin asphalt by nearly 30 percent.
“The team tested the material on parts of the road being built under SH 2013 project, connecting Nuzvid and Mylavaram (in Andhra Pradesh) designed for a traffic of 1,213 commercial vehicles per day,” said Sireesh Saride, the Principal Investigator of the project.
The researchers treated fly ash with sodium hydroxide to convert the fly ash into geopolymer. This polymer is suitable for binding with RAP particles thereby rendering it stronger. “Activating fly ash is not very new, but using it for this application is very new. Generally, cement is used in place of fly ash to get better performance, but much more expensive,” Saride adds.
The team observed that by testing a proportion of asphalt and geopolymer in the ratio 80:20 with 40% fly ash, meets the standards stipulated by Indian Roads Congress as well as the American Association of State Highway and Transportation Officials (AASHTO). “We have managed to use RAP up to 60% (and also up to 80% in the lab conditions) with appropriate stabilization techniques (fly ash geopolymer) and balanced between the performance and cost,” added Saride.