Right Grade of Bitumen for Flexible Pavements: Indian Perspective
M.N. Nagabhushana, Scientist, Flexible Pavemments Division, Central Road Research Institute, New Delhi
Introduction
Indian road transportation infrastructure is rapidly expanding with the ambitious development of road networks under National Highways Development Programme (NHDP), State Highways Improvement Programmes (SHIPs), Bharat Nirman, Pradhan Mantri Gram Sadak Yojana (PMGSY) etc. Also, other category roads and airports are largely expanded. The fast growing Indian economy will further demand for road transport network with a high quality pavement structure as the main corridors are required to cater to very heavy traffic-both in terms of number and axle loading. Road-laying under the Golden Quadrilateral project and the North-South and East-West corridors project of National Highways Authority of India (NHAI) has been quantitatively significant. According to the outcome budget of the Ministry of Shipping, Road Transport and Highways, Govt. of India, 5,694 km of road-laying and four-lining out of a total of 5,846 kilometres were targeted for completion in the present fiscal year. While these road development projects help in adding considerable infrastructural assets, their construction and subsequent maintenance phases require huge amount of suitable pavement materials.
Currently, majority of the Indian roads are flexible pavements, the ones having bituminous layer/s. earlier, there used to be scarcity of cement and India went for flexible pavements with bituminous toppings. Now, flexible pavement are preferred over cement concrete roads as they have a great advantage that these can be strengthened and improved in stages with the growth of traffic. Another major advantage of these roads is that their surfaces can be milled and recycled for rehabilitation. The flexible pavements are less expensive also with regard to initial investment and maintenance.
