FUTURE OF BITUMEN EMULSION AS-AN ENVIORNMENTAL FRIENDLY ROAD CONSTRUCTION MATERIAL

Abstract

Bitumen emulsion is a thermodynamically unstable· heterogeneous system in which finelyground bitumen particles are dispersed in an aqueous medium. In most parts of the worldusage of bitumen emulsion as a road construction material has increased during the recentpast partially replacing penetration grade bitumen (tar) and cutback bitumen due toenvironmental reasons. In Sri Lanka bitumen emulsion is used for certain roadconstruction work. However, still there is somewhat reluctance among road engineers touse bitumen emulsion as a substitute for 01her types.

There are numerous uses for bitumen emulsion utilizing highly varied techniques, whichresults in several different formulations; namely cationic and anionic depending on particlecharges and rapid setting, medium setting and slow setting depending on its speed ofseparation of bitumen from aqueous medium. In Sri Lanka, cationic type bitumen emulsionis used, as majority of the available local aggregates are acidic except Jaffna limestone.

Bitumen emulsion is suitable to the requirements of all road maintenance work. Ease ofstorage and transport make it possible to set up numerous depots and its ease and facility ofuse enable work to be done quickly causing minimum disturbance to the users. It may bethe first choice bituminous material for all maintenance work on road pavements due toenvironmental friendliness, provided that correct proportions and standard specificationsare being used.

Bitumen emulsion has proven itself as a binder, which utiJises very low energyconsumption in road maintenance and laying of surface dressings. Penetration gradebitumen requires heating at construction sites, which emit smoke with chemicals and alsoit needs fuel, which is a non-renewable rCS0\JfCC.Kerosene that is used for cutting back theviscosity of bit urn en is also a non-recoverable waste when curing takes place on the road.

ThIS paper identifies the advantages of using bitumen emulsion over other traditionalalternatives and investigates the reasons for the reluctance to use locally. The paperproposes suitable remedial measures to overcome the perceived disadvantages and increasethe use of bitumen emulsion as an environment friendly alternative.