16-05-2014, 02:23 PM
RUBBERIZED BITUMEN FOR ROAD WORKS
Introduction
Development of infrastructural facilities like road is vital for the economic growth of a country. Good roads improve connectively, accessibility, mobility and productivity. The use of bitumen modified using polymeric materials like natural rubber, synthetic rubbers and plastic etc. have helped to a great extends in improving the quality of roads. Bitumen thus modified employing polymers are known as Polymer Modified Bitumen (PMB). Out of these Natural Rubber Modified Bitumen (NRMB) is widely used in road construction which is obtained by adding natural rubber latex to boiling bitumen.
HISTORY AND PRESENT STATUS
Rubberisation was first experimental in Kerala way back in 1974 when a 1km Stretch of the MC road was paved with Natural Rubber Modified Bitumen (NRMB). Though the experiments was successful there were not many takers for the process, mainly because of the shortage of quality NRMB.
After a long time Kochi Refineries started commercial production of rubberised bitumen in 1999. The Refineries is having a commercial plant with a production capacity of 15000 tonnes per year at a cost of Rs. 40 lakhs
PREPARATION OF RUBBERISED BITUMEN
Among various forms of rubber used, it is seen that rubber latex is the best form of rubber that can be incorporated into bitumen. The initial process for the production of NRMB was mostly insitu mixing of natural rubber latex with bitumen. For this the bitumen was heated to about 1400C and small amounts of (1%) of kerosene was added as viscosity modifier. To the boiling bitumen , natural rubber latex about 2 to 4% by weight of bitumen was added , stirred well and kept for about 2 hrs. for homogenization.