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IS 1208:1978 is the Indian Standard (BIS) for methods for testing tar and bitumen: determination of ductility. This standard outlines the test method for determining the ductility of bituminous materials by measuring the distance in centimeters to which a standard briquette elongates before breaking under specific conditions of temperature and speed.
Describes the method for determining the ductility of bituminous materials, indicating their ability to deform without breaking, relevant for waterproofing flexibility.
! Temperature control is highly critical; a deviation of even 0.5°C can significantly alter ductility results.
! If the thread of bitumen sags and touches the bottom of the water bath, or floats to the surface, the specific gravity of the water must be adjusted (e.g., by adding methyl alcohol or sodium chloride) and the test repeated.
! Carefully cut the excess bitumen from the briquette using a hot, straight-edged putty knife from the center towards the ends to prevent pulling the material out of the mould.
Standard Method of Test for Ductility of Asphalt Materials
Defines the procedure for determining the ductility of a bituminous material by measuring the elongation of a briquette specimen.
ASTM D113-07ASTM International (US)
HighWithdrawn
Standard Test Method for Ductility of Bituminous Materials
Formerly the primary US standard for measuring bituminous material ductility; methodology was nearly identical to IS 1208.
EN 13589:2018CEN (European Union)
MediumCurrent
Bitumen and bituminous binders - Determination of the tensile properties of modified bitumen by the force ductility method
Measures tensile properties by pulling a briquette, but focuses on force and energy, not just elongation distance.
Key Differences
≠The standard test temperature in IS 1208 is 27 °C, which reflects a typical Indian climate, whereas the standard temperature in AASHTO T 51 and the former ASTM D113 is 25 °C.
≠IS 1208 specifies reporting the mean of two normal tests, while AASHTO T 51 requires the average of three normal tests for a result.
≠The primary US equivalent, ASTM D113, has been withdrawn without a direct replacement, indicating a shift in US practice towards performance-based rheological tests (e.g., MSCR), a move not yet reflected in the continued use of IS 1208.
Key Similarities
≈The fundamental test principle is identical: measuring the distance a standard briquette of bitumen can be elongated at a specified rate and temperature before breaking.
≈The dimensions and geometry of the standard test briquette (mould) are identical across all standards (IS, AASHTO, and former ASTM), with a 10 mm x 10 mm minimum cross-section.
≈The standard rate of pull for the test is identical, specified as 50 mm/min (5 cm/min) in both IS 1208 and AASHTO T 51.
≈The general apparatus, including a temperature-controlled water bath and a machine with clips to pull the specimen, is conceptually the same.
Parameter Comparison
Parameter
IS Value
International
Source
Standard Test Temperature
27 ± 0.5 °C
25 ± 0.5 °C
AASHTO T 51-18
Rate of Pull
50 ± 2.5 mm/min
50 ± 2.5 mm/min
AASHTO T 51-18
Briquette Mould Min. Cross-Section
10 mm x 10 mm
10 mm x 10 mm
AASHTO T 51-18
Briquette Mould Overall Length
75.0 ± 0.5 mm
75.0 ± 0.5 mm
AASHTO T 51-18
Briquette Mould Distance Between Clips
30.0 ± 0.3 mm
30.0 ± 0.3 mm
AASHTO T 51-18
Number of Replicates for Result
Mean of 2 tests
Average of 3 tests
AASHTO T 51-18
Reporting Units
centimetres (cm)
centimetres (cm)
AASHTO T 51-18
⚠ Verify details from original standards before use
What is the standard pulling speed for the ductility test?+
The clips must be pulled apart at a uniform speed of 50 ± 2.5 mm per minute.
At what temperature is the ductility test conducted in India?+
The standard test temperature specified in IS 1208 is 27 ± 0.5 °C.
How is ductility measured and reported?+
It is measured and reported as the distance in centimeters (cm) that the standard briquette stretches before the thread breaks.
What does the ductility value indicate about bitumen?+
It indicates the material's ability to undergo deformation without rupture, highlighting its adhesive and tensile properties which are crucial for pavement durability.