BITUMEN: is defined as “A viscous liquid, or a solid, consisting essentially of hydrocarbons and their derivatives, which is soluble in trichloroethyelene and is substantially nonvolatile and softens gradually when heated. It is black or brown in colour & possesses waterproofing and adhesive properties. It is obtained by refinery processes from petroleum, and is also found as a natural deposit or as a component of naturally occurring asphalt, in which it is associated with mineral matter.

Bitumen or bituminous binder available in India is mainly of the following types :

Viscosity Grade :

Paving grade bitumen is the bitumen obtained from refineries and conforms to IS 73. Recently, the third revision of Indian Standards for Paving Bitumen Specifications IS 73:2006 has been released by Bureau of Indian Standards. Three grades of Bitumen confirming to IS 73: 1992 are manufactured in India. In this third revision grading of Bitumen is changed from penetration grade to viscosity grade. To improve the quality of Bitumen, BIS revised IS-73-1992 Specifications based on viscosity grade (viscosity @ 60 deg. C) in July 2006. As per the Specifications, there are four grades VG-10, VG-20, VG-30 & VG-40.

With the current revision several key issues are addressed, like :

Performance at high temperatures by adopting a viscosity-graded bitumen specification (based on viscosity at 60 ºC), in place of the current penetration-graded specification (based on penetration at 25 ºC)

Issues relating to compaction, which the tender asphalt mixtures create as push and shove under the roller wheels, have also addressed by having a requirement of minimum viscosity at 135ºC, it will be helpful in minimizing the tender mix problems in the field.

Adoption of viscosity-graded paving bitumen specifications will also reduce the number of total tests to, without compromising the quality of bitumen and also no new tests are required in implementing this specification.

Viscosity grades Bitumen are categorized according to Viscosity (degree of fluidity) grading. The higher the grade, the stiffer the Bitumen. In Viscosity Grade, Viscosity tests are conducted at 60 deg. C and 135 deg. C, which represents the temperature of road surface during summer and mixing temperature respectively. The penetration at 25 deg. C, which is annual average pavement temperature, has been also retained in Specifications.

Viscosity Based System

The actual tests conducted are as follows:

Viscosity Test

Viscosity at 135 Deg.C is a fair indicator of the ability of bitumen to coat the aggregates properly. In order to get best coating the viscosity has to be optimum. Too viscous bitumen would result in inadequate and non-uniform coating of the aggregates. Very low viscosity would again result in inadequate coating as the bitumen will tend to bleed. Therefore viscosity at 135 Deg.C is a true reflection of the quality of bond that is likely to be formed with the aggregate. Various testing equipments like Capillary Viscometer, Cup Viscometer, Tar Viscometer, etc. can be used for testing the viscosity.

Viscosity at 60 Deg.C is a very good indicator of the resistance of bitumen to melting/flowing on the road. It is considered to be replacement test for Softening Point test. Some specifications have replaced softening point test with Viscosity at 60OC. However, at many :

places both the tests are carried out as both the tests are empirical and have their own limitations.

BITUMEN SPECIFICATION AS PER IS 73:2006

Characteristics	Requirements			Test Method
	VG10	VG30	VG40
Softening point, Deg C, min	40	47	50	IS 1205:1978
Penetration at 25 Deg C	80 - 100	50 – 70	40 – 60	IS 1203:1978
Flash point, Degree C, min	220	220	220	IS 1209:1978
Solubility in trichloroethylene, %, min	99	99	99	IS 1216:1978
Absolute Viscosity, 60 Deg C, poises, min	800	2400	3200	IS 1206 (P2):1978
Kinematic Viscosity, 135Deg.C, CST, min	250	350	400	IS 1206 (P3):1978
Tests on residue from thin film over test / RTFOT:
Viscosity ratio at 60 Degree C, max	4	4	4	IS 1206(P2):1978
Ductility at 25 Deg. C, cm, min, after thin film over test	75	40	25	IS 1208:1978

MODIFIED BITUMEN PLANT

• PMB/CRMB plant is specially designed to meet the exact demand of latest bitumen modification technology.
• PMB/CRMB plant incorporates the highly accurate flow control and weighing system ensuring accurate and continuous flow of bitumen and modifier exactly according to the specified requirement without premixing them.
• PMB/CRMB production capacity from 10-15 MT/Hr.

CHARACTERISTICS OF MODIFIED BITUMEN PLANT

• Globally advanced automatic production pattern using PLC Control system.
• Highly Efficient high shear mill with high efficiency and long working life.
• Incorporating E+H Bitumen Mass flow meter and frequency conversion Ranton pump, the bitumen system ensure accurate measurement, for different production capacities.
• Electronic weighing system, guarantee the accuracy of weighing and continuous measurement.
• The finished modified bitumen can be directly sent to the storage tanks without extra transportation cost.
• Unique liquid level control system matched with small sized pre mixing tank ensuring homogeneous mixing of bitumen and modifier.