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IS 10082:1981 is the Indian Standard (BIS) for method of test for the determination of tensile strength by indirect tests on rock specimens. This standard specifies the method for determining the indirect tensile strength of rock specimens, primarily through the Brazilian test. It covers the required apparatus, specimen dimensions and preparation, testing procedure, and the formula for calculation.
Method of test for the determination of tensile strength by indirect tests on rock specimens
Standard Test Method for Splitting Tensile Strength of Intact Rock Core Specimens
Defines the procedure for determining the splitting tensile strength of rock core discs, commonly known as the Brazilian test.
ISRM Suggested Methods (2007)International Society for Rock Mechanics (ISRM), International
HighCurrent
Suggested Method for Determining Tensile Strength of Rock Materials (Brazilian Test)
Provides a globally recognized recommended methodology for conducting the Brazilian test on prepared rock specimens.
Key Differences
≠IS 10082 specifies a loading rate in terms of force (100 to 200 N/s), whereas ASTM D3967 specifies a time to failure (1 to 10 minutes) and ISRM suggests a much faster time to failure (15 to 30 seconds).
≠ASTM D3967 and ISRM mandate or strongly recommend the use of curved loading jaws with specific radii to reduce contact stress concentrations. IS 10082 describes loading between flat platens with packing strips, which is a less controlled method.
≠The acceptable range for the specimen thickness-to-diameter ratio (t/D) varies. IS 10082 specifies 0.25 to 0.75, while ASTM D3967 allows a slightly wider range of 0.20 to 0.75. ISRM simply recommends a ratio of approximately 0.5.
≠The minimum specimen diameter requirements are slightly different: IS 10082 requires 'not less than 50 mm', ASTM D3967 requires a minimum of 47 mm (NX core), and ISRM recommends a diameter of at least 54 mm (NX core).
Key Similarities
≈All standards are based on the same indirect tensile testing principle, where a cylindrical disc specimen is compressed diametrically until it splits (the 'Brazilian Test').
≈The fundamental formula for calculating the splitting tensile strength (σt) is identical across all standards: σt = 2P / (πDt).
≈All three standards require the test specimen to be a circular disc prepared from a rock core, with flat, parallel faces cut perpendicular to the core's longitudinal axis.
≈The validity of the test in all standards is contingent upon the specimen failing by splitting along the loaded diameter, with the primary fracture initiating near the center.
Parameter Comparison
Parameter
IS Value
International
Source
Specimen Shape
Circular disc
Circular disc
ASTM D3967-23
Minimum Specimen Diameter
Not less than 50 mm
Minimum 47 mm (NX core size)
ASTM D3967-23
Thickness-to-Diameter Ratio (t/D)
0.25 to 0.75
0.20 to 0.75
ASTM D3967-23
Thickness-to-Diameter Ratio (t/D)
0.25 to 0.75
Recommended to be approx. 0.5
ISRM Suggested Methods (2007)
Loading Rate
100 to 200 N/s
Constant rate to cause failure in 1 to 10 minutes
ASTM D3967-23
Loading Platen/Jaw Type
Flat platens with packing strips
Curved loading jaws with radius = 1.5 x specimen radius
ASTM D3967-23
Calculation Formula
σt = 2P / (πDt)
σt = 2P / (πDt)
ASTM D3967-23 / ISRM (2007)
Minimum Number of Specimens
At least three
Sufficient for a representative average (suggests at least 5)
ASTM D3967-23
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Minimum specimen diameter45 mm
Specimen length to diameter ratio (L/D)0.5
Recommended loading rate200 N/s
Minimum number of test specimens5
Permissible variation in specimen diameter0.2 mm
Key Formulas
σt = 2P / (πDL) — Tensile strength from Brazilian Test