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IS 5748:1969 is the Indian Standard (BIS) for methods of test for tensile strength of asbestos fibre. This standard specifies the methods for determining the tensile strength of asbestos fibres. It covers two distinct methods: Method A for longer spinning fibres and Method B for shorter fibres. The document details the necessary apparatus, specimen preparation techniques, testing procedures, and the formula for calculating tensile strength.
Methods of test for tensile strength of asbestos fibre
Quebec Standard Test Method for Strength Unit (SU)QAMA (Quebec Asbestos Mining Association) / CRIQ (Centre de recherche industrielle du Québec), Canada
HighWithdrawn
Method for the Determination of the Strength of Asbestos Fibre
Both standards evaluate the reinforcing potential of asbestos fibre by testing a standardized fibre-cement composite.
ASTM D3639-92ASTM International, USA
HighWithdrawn
Standard Test Method for Classification of Asbestos by Quebec Standard Test
Directly incorporates the QSTM procedures, including the strength unit test, as a method for asbestos fibre classification.
GOST 22987-90GOST, Russia
MediumWithdrawn
Asbestos and asbestos-cement materials. Method for determination of tensile strength
Specifies a method for determining the tensile strength of asbestos-cement composites, similar in principle to the IS code.
Key Differences
≠IS 5748 specifies a direct tensile test on dog-bone shaped specimens, whereas the predominant international method (QSTM) uses a flexural strength test (Modulus of Rupture) on rectangular specimens.
≠The result in IS 5748 is reported as direct tensile strength (e.g., in kgf/cm²), while the QSTM/ASTM method yields a calculated, comparative value known as 'Strength Units' (SU).
≠The standard water curing period in IS 5748 is 28 days, which is significantly longer than the typical 24-hour water cure or accelerated autoclave curing cycles used in the QSTM protocol.
≠The mass ratio of fibre to cement is different; IS 5748 specifies a 1:7 ratio, while the QSTM specifies a 1:9 ratio.
Key Similarities
≈Both the Indian and international standards use the same fundamental principle: evaluating fibre strength indirectly by creating and testing a standardized asbestos-cement composite.
≈The initial specimen preparation is very similar, involving the creation of a dilute aqueous slurry of fibre and cement that is mixed and then dewatered under vacuum in a filtration apparatus to form a test pad.
≈The ultimate purpose of both test methods is identical: to provide a reproducible quality control measure for grading asbestos fibre based on its ability to reinforce a cementitious matrix.
≈Both standards mandate the use of ordinary Portland cement conforming to the respective national standards (e.g., IS 269 in India).
Parameter Comparison
Parameter
IS Value
International
Source
Test Type
Direct Tensile Test
Flexural Strength Test (Modulus of Rupture)
Quebec Standard Test Method for Strength Unit (SU)
Specimen Shape
Dog-bone shaped
Rectangular bar
Quebec Standard Test Method for Strength Unit (SU)
Fibre to Cement Ratio (by mass)
1:7
1:9
Quebec Standard Test Method for Strength Unit (SU)
Standard Curing Period (Water)
28 days
24 hours (followed by drying or autoclave)
Quebec Standard Test Method for Strength Unit (SU)
Pressing Pressure on Wet Pad
110 kgf/cm²
140 kgf/cm² (~2000 psi)
Quebec Standard Test Method for Strength Unit (SU)
Final Result Unit
Tensile Strength (kgf/cm²)
Strength Units (SU) derived from Modulus of Rupture
Quebec Standard Test Method for Strength Unit (SU)
Solid-to-Water Ratio in Slurry
100 g (12.5g fibre + 87.5g cement) in 2000 ml water
1000 g (100g fibre + 900g cement) in 20,000 ml water
Quebec Standard Test Method for Strength Unit (SU)
⚠ Verify details from original standards before use
Key Values3
Quick Reference Values
Test specimen mass (Method A)0.0250 ± 0.0001 g
Number of test specimens10 for each sample
Rate of loadingsuch that the specimen breaks in 10 ± 2 seconds
Key Formulas
Tensile Strength (kg/cm²) = (Breaking Load in kg) / (Cross-sectional Area in cm²)
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 3 - Apparatus
Clause 4 - Sampling and Preparation of Test Specimen
Clause 5 - Procedure (Method A - For Longer Spinning Fibres)
Clause 6 - Procedure (Method B - For Shorter Fibres)
No, IS 5748:1969 has been withdrawn by the Bureau of Indian Standards and is no longer in force.
What property does this standard measure?+
It measures the tensile strength of asbestos fibres, which indicates their resistance to being pulled apart.
Why were two different methods specified?+
Method A was for longer, spinnable fibres used in textiles, while Method B was adapted for the shorter fibres commonly used as reinforcement in asbestos-cement products.