An appropriate method of production of rubberrised bitumen for road surfacing

Abstract

A laboratory scale method comprising two stages has been developed to produce rubberised bitumen based upon natural rubber. In the first stage of the method, natural rubber in the form of field latex, stabilised previously with ammonia and potassium hydroxide, was added in required proportion into 80/100 grade bitumen melt at 95°C, to give about 3% rubber in bitumen by mass. To facilitate the addition, the contents were continuously stirred by means of a multi-stage impulse counter current impeller (pitched paddle stirrer). In the second stage, the resulting temperature of the mix ' was gradually raised to 100°C. to vapourise the water content in the latex. The problems encountered during the vaporisation of water such as frothing, and rise in viscosity of the mix were overcome by altering the speed of the stirrer unit appropriately. The bitumen-rubber blend thus obtained, on testing for its quality, exhibits bettei technical properties than 80/100 grade bitumen for application in road surfacing