Goans have witnessed much damage to the newly hot-mixed roads in the state due to traffic congestion and fury of the monsoons. However stretches of ‘char’ waste roads in a mining area of Santona have survived rough weather and heavy traffic for four years.
A case study taken up by students of Goa Engineering College (GEC), Farmagudi reported that char aggregate (a processed solid waste of sponge iron industry) was reused in hot-mixing of a 3.2km road span from Sai temple to Fomento mines in Santona, to explore its potential as an alternative to conventional road-construction material.
“The tests have shown that it is a strong and durable material and conforms to specifications laid down by Ministry of Road Transport and Highways,” said K G Guptha, professor and head of civil engineering, Goa engineering College.
Traditionally, road contractors use gravel or rubble for the base course, then one or two layers of bitumen, depending on the requirement, and finally hot-mix it with asphalt concrete. In this case, char waste was used for the base course, followed by two layers of bitumen and topped with purely char waste for the 100m stretch.
The main road from Sai temple to Fomento mines was laid with a base course of 25% char waste, but topped with conventional material. However, these roads which were developed in 2012 are gradually deteriorating, but the issue does not concern the authorities.
“After four years, it is showing some damage, but it is minor. Trucks of 15 to 40 tonnes gross ply over it regularly,” says Keshav Babu, general manager (technical), GSPL.
National rural road development agency has agreed to consider it as a future raw material due to its merits as an eco-friendly and cheaper alternative.