Use of Natural Rubber Modified Bitumen Emulsion in Road Maintenance – A Step Forward in the Direction of Eco-Effectiveness

Serious concerns with regard to the environmental protection, particularly the carbon and volatile organic compounds emissions into the atmosphere, both in developed world as well as in many developing countries, has thrown open a great challenge to the Highway Engineers to look for alternate materials and techniques for construction and maintenance of roads. In this context, some materials and techniques, which were so far thought and considered to be unsuitable and unreliable, are now required to be investigated for their potential applications in the road sector due to these expressions and constraints. Cold paving techniques using bitumen emulsions have, in the past, demonstrated eco-effectiveness and their outstanding performance as compared to the warm and hot mixed bituminous materials. Microsurfacing, involving the use of modified bitumen emulsion, has demonstrated great potential for use as preventive maintenance treatment for highways in India and abroad. Majority of the modified bitumen emulsions used worldwide are SBR latex based, which are costly and need to be imported for modification of emulsions. India produces fairly large amount of natural rubber latex, which is considered to be a potential modifier for manufacture of modified emulsion in Asian countries. In this context, laboratory and field investigations were taken up in India, which involved production and application of natural rubber latex modified emulsions for microsurfacing projects. Experimental road sections involving the use of indigenously manufactured natural rubber latex modified bitumen emulsion in microsurfacing were constructed on National Highway No. 37 near Guwahati, the capital city of Assam state in India. The main purpose of this study was to demonstrate and disseminate the indigenously developed, cost effective and eco-friendly technology utilizing natural rubber latex modified emulsion in microsurfacing as the preventive maintenance treatment.This paper deals with the formulation of natural rubber modified bitumen emulsion and its characteristics / properties, design and construction of experimental road sections, performance monitoring data and development of specifications for natural rubber latex modified bitumen emulsions in Indian perspective.