Bitumen is prepared by the refining of crude petroleum by suitable methods.
In the third revision of IS:73-2006 grading of bitumen was changed from penetration grade to viscosity grade.
Grades of Bitumen & Selection of Bitumen:
Bitumen is classified into four grades based on the viscosity, and suitability recommended for maximum air temperature as given below:
Latest revision has also rationalized the Bitumen selection process by categorizing the binder grade based on design maximum air temperature.
So,The choice of the grade depends upon the design maximum air temperature of the location where the binder has to be used.
Requirements of Bitumen :
The various grades of bitumen shall conform to the requirements prescribed below:
In latest revision (2013), emphasis is given to the viscosity measurement at 60°C & hence viscosity ranges are provided for all the grades instead of a range for penetration as specified in the third revision(2006). Rather,Minimum value of penetration at 25°C is stipulated.
Tests on Bitumens:
Tests on Bitumen are given above in table for requirements for bitumen.
Adoption of viscosity-graded paving bitumen specification also reduced the number of total tests to seven, resulting in reduced cost of testing paving bitumen.
Ductility test is no longer mandatory for specification compliance.
This eliminated empirical tests/parameters such as, penetration ratio, paraffin wax content, and Fraass breaking point without compromising the quality of bitumen.
No. of Samples for Test : The number of containers to be selected at random from the lot shall depend upon the size of the lot given below:
Criteria for Conformity : The lot shall be considered as conforming to the requirements of bitumen, if the condition mentioned below is satisfied.
Condition: From the test results of absolute viscosity at 60°C,penetration and softening point, the mean ( X ) and the range (R) shall be calculated. The following conditions shall be satisfied:
a) [ x –0.6R] shall be greater than or equal to the minimum specification limit specified in Table for requirements of bitumen and
b) [ x + 0.6R] shall be less than or equal to the maximum specification limit specified in Table for requirements of bitumen.
-BRO TI 25 may be read with this latest revision of bitumen.
In the third revision of IS:73-2006 grading of bitumen was changed from penetration grade to viscosity grade.
Bitumen is classified into four grades based on the viscosity, and suitability recommended for maximum air temperature as given below:
Latest revision has also rationalized the Bitumen selection process by categorizing the binder grade based on design maximum air temperature.
So,The choice of the grade depends upon the design maximum air temperature of the location where the binder has to be used.
Requirements of Bitumen :
The various grades of bitumen shall conform to the requirements prescribed below:
In latest revision (2013), emphasis is given to the viscosity measurement at 60°C & hence viscosity ranges are provided for all the grades instead of a range for penetration as specified in the third revision(2006). Rather,Minimum value of penetration at 25°C is stipulated.
Tests on Bitumens:
Tests on Bitumen are given above in table for requirements for bitumen.
Adoption of viscosity-graded paving bitumen specification also reduced the number of total tests to seven, resulting in reduced cost of testing paving bitumen.
Ductility test is no longer mandatory for specification compliance.
This eliminated empirical tests/parameters such as, penetration ratio, paraffin wax content, and Fraass breaking point without compromising the quality of bitumen.
No. of Samples for Test : The number of containers to be selected at random from the lot shall depend upon the size of the lot given below:
Condition: From the test results of absolute viscosity at 60°C,penetration and softening point, the mean ( X ) and the range (R) shall be calculated. The following conditions shall be satisfied:
a) [ x –0.6R] shall be greater than or equal to the minimum specification limit specified in Table for requirements of bitumen and
b) [ x + 0.6R] shall be less than or equal to the maximum specification limit specified in Table for requirements of bitumen.
-BRO TI 25 may be read with this latest revision of bitumen.
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