White-topping and the pothole filling machine, Python, have long been the BBMP’s go-to solution for bad roads. White-topping is the process of covering the existing bitumen layer with concrete.
But these technologies may soon become passe, as the civic body wants to experiment with micro-surfacing using a machine called Road Doctor, which is being used in Chandigarh and Chennai.
The Bruhat Bengaluru Mahanagara Palike (BBMP) has cleared a pilot project on Ballari Road, which will be executed in August.
A senior engineer explained that micro-surfacing a road is like laminating plywood.
The road surface is coated with a 6mm layer of rubberised derived bitumen blended with asphalt rubber to ensure water does not seep into the road bitumen, thereby preventing wear and tear, and potholes. The 6mm layer is slapped onto the road surface at high pressure.
According to B.S. Prahallad, Chief engineer (major roads), BBMP, the use of rubber prevents seepage of water. “All water will end up in the drain. The road surface will be uniform, smooth and skid proof,” he said.
Prof. T.G. Sitharam, Civil Engineering Department, Indian Institute of Science, said that rubberised bitumen is used extensively in the United States of America.
“It acts as a water-proofing membrane and prevent seepage. Rubber will give the bitumen a self healing characteristic, which will not allow formation of individual cracks. The rubber will fill up most cracks,” he said.
The cost factor
While the cost of laying bitumen and asphalting a road is nearly ₹250 per square metre, the company offering this technology will micro-surface a road for an average of ₹150 per square metre, and has offered to maintain the road for three years, officials said.