A Warm WELCOME to all….

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RUBBERISED BITUMEN FOR ROAD WORKS

Presented by FINCY

BABU S7 CE

Roll no: 25 S.N.G.C.E

Under the guidance of Mrs. S.USHA.

IntroductionDevelopment 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. Uniformly

blended NRMB thus obtained was used for the urbanization of roads.

FLOWCHART FOR BITUMINOUS PAVEMENT CONSTRUCTION

CASE STUDY The following laboratory tests were

carried out on the different blends as per relevant is

Penetration testSoftening point (0C) Ductility (cms)Loss on heating (%)Viscosity Stripping value test

Physical properties of 80/100 bitumen with rubber latex of varying

concentrations

RESULTS AND DISCUSSIONS

Figure 1Variation of penetration value with % concentration of rubber latex in 80/100 bitumen

Figure 2Variation of Softening point value with % concentration of rubber latex in 80/100 bitumen

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Figure 3Variation of Ductility with % concentration of rubber latex in 80/100 bitumen.

COMPARISON BETWEEN PERFORMANCE CHARACTERISTICS OF NRMB AND

CONVENTIONAL BITUMEN

COMPARISON OF PERFORMANCE CHARACTERISTICS OF NRMB OVER

OTHER MODIFIED BITUMEN

ADVANTAGES OF NRMB• For superiority in quality to ordinary bitumen in

terms of penetration, softening point and elastic recovery. • Less affected by changes in temperature. The

effect of rubber is to increase the resistance to flow at high temperature and at the same time improve the resistance to brittle fracture at low temperature. • More retention of aggregates and elimination of

bleeding. • Reduces environmental pollution by less

consumption of bitumen.• Conserves energy, natural resources and bitumen.• Enhances tyre rolling and save fuel.• Reduces traffic noise pollution.

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• More comfort riding. • The roads surfaced with NRMB provide more

service life than normal bitumen roads.• Reduction in the road maintenance cost.• It can be applied on the road by conventional

mixing and mechanized techniques. • As a result of improved resistance of rubberised

bitumen to temperature, the tendency for pavement cracking and fatting up is absent in roads surfaced with it. • Rubberised bitumen shows improved adhesion

with aggregates. • Rubberisation of roads will create additional

demand for natural rubber and it will ensure a remunerative price for rubber farmers.

POSSIBLE PROBLEMS It is usually necessary for the NRMB to be held in a tank that is capable of being agitated in someway, as the polymers being of a different density to the bitumen tend to separate if kept in storage for prolonged periods. The polymer additive can be destroyed by too high temperature for a long period of time after mixing, even the binder storage times should be kept as short as possible or deterioration of the polymer may take place. It was found to be time consuming and sometimes the mixing was not uniform due to lack of experience of the workers.

COST OF RUBBERISATIONBased on commercial trails conducted in India and abroad , additional cost for rubberised roads comes to 15-20% compared to bituminous roads, however it is possible to get about at least 50% more service life for rubberised roads than normal bitumen. Also the studies conducted by the Central Road Research Institute, New Delhi, reveals that the cost for periodic maintenance of these roads can be reduced by 35% compared to that of the bituminous roads. The suggested renewal cycle with NR modified bitumen is 7-8 years, compared to 4-5 years for conventional bitumen. Better fuel savings are also possible with rubberisation. Thus the extra expenditure required for rubberisation is more than compensated.

CONCLUSIONAddition of rubber in any form to bitumen produces

favourable changes in the properties of bitumen. It is found that rubberised bitumen was able to overcome the disadvantages of conventional bitumen roads, which melt

during summer and become brittle during winter. Conclusions drawn from the present study are:

 The roads surfaced with NRMB provide atleast 50% more

service life than normal bitumen roads. Reduction in the road maintenance cost by 30%.Enhances tyre rolling and save fuel by 10%.Reduces traffic noise pollution.More comfort riding.

Reference Ronald E. Baker , (1998), Polymer Modified

Bitumen, Journal of Indian Highways , pp 85-95. P. Jagajothi, K. Nagarajan, D. Thirunakkarasu,

(1999), Rubberised Bitumen for Road Works, Journal of Indian Roads Congress, 60, pp 133-163.

S.J.P. Dharmaraj, (2002) , Rubberised Bitumen for Roads, Journal of Indian Highways, pp 55- 61.

S.K. Khanna, (2001), “Highway Engineering”, 8th edition, Nem Chand & Bros Publications, Roorkee Press, Mahavir Marg.

Aravindan, (2002), “Road Rubberisation emerging as new hope for growers”, The Hindu Business Line , February 10, 2002.

Thank you…

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