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IS 12979:1990 is the Indian Standard (BIS) for mould for determination of linear shrinkage -. This standard specifies the material requirements and dimensions for the mould used in the determination of linear shrinkage of soils. The mould is a trough-shaped bar, typically made of brass, used as per the test method in IS 2720 (Part 20).
! Ensure the internal surfaces of the mould are coated with a thin layer of grease or petroleum jelly before placing the soil paste to prevent sticking.
! The dimensional accuracy is critical for the test result; inspect the mould for any warping or damage before use.
! This apparatus is specifically for the test procedure outlined in IS 2720 (Part 20) - Determination of linear shrinkage.
Standard Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and Concrete
Specifies apparatus, including an identical size mould (25x25x285 mm), for length change measurement.
BS EN 12617-4:2002BSI / CEN, UK / Europe
MediumCurrent
Products and systems for the protection and repair of concrete structures - Test methods - Part 4: Determination of shrinkage and expansion
Covers shrinkage determination, but typically uses a different mould size (40x40x160 mm).
ISO 1920-8:2009ISO, International
MediumCurrent
Testing of concrete - Part 8: Determination of drying shrinkage of concrete for samples prepared in the field or in the laboratory
Specifies shrinkage testing but for larger standard specimen sizes (e.g., 75x75x280 mm).
AS 1012.13-1992Standards Australia, Australia
MediumCurrent
Methods of testing concrete - Method 13: Determination of the drying shrinkage of concrete
Covers moulds for shrinkage, but for a different specimen size (75 x 75 x 280 mm gauge length).
Key Differences
≠IS 12979 specifies only the mould, whereas its closest equivalent, ASTM C490, is a broader 'Standard Practice' covering the mould, comparator, reference bar, and usage procedure.
≠While IS 12979 and ASTM C490 specify an identical 25x25x285 mm specimen, European (BS EN) and ISO standards for shrinkage typically require different specimen sizes, such as 40x40x160 mm or 75x75x280 mm.
≠Manufacturing tolerances can differ. For instance, the flatness tolerance for the internal faces of the mould is 0.05 mm in IS 12979, while ASTM C490 requires a stricter tolerance of 0.025 mm (0.001 in).
≠ASTM C490 provides a more prescriptive performance requirement for the reference bar material (CTE not exceeding 2 x 10^-6 /°C), while IS 12979 gives a more general recommendation for 'steel with low coefficient of thermal expansion'.
Key Similarities
≈All standards specify the use of a rigid, accurately machined prism mould to create specimens for measuring linear shrinkage or expansion.
≈The fundamental design requires the mould to hold gauge studs at the center of each end face of the specimen, which serve as the reference points for length measurement.
≈The moulds are designed to be disassembled (e.g., with removable side and end plates) to allow for the careful demoulding of the hardened specimen without causing damage or stress.
≈The materials specified for the mould (e.g., steel or cast iron) and gauge studs (e.g., stainless steel) are chosen for their durability and resistance to corrosion from cement paste.
Parameter Comparison
Parameter
IS Value
International
Source
Specimen Dimensions
25 x 25 x 285 mm
1 x 1 x 11.25 in. [25 x 25 x 285 mm]
ASTM C490
Effective Gauge Length
250 mm
10 in. [250 mm]
ASTM C490
Alternative Specimen Size
Not specified
40 x 40 x 160 mm
BS EN 12617-4
Flatness Tolerance (Mould Interior Face)
0.05 mm
0.001 in [0.025 mm]
ASTM C490
Interior Corner Angle Tolerance
90° ± 0.5°
90° ± 0.5°
ASTM C490
Gauge Stud Material
Stainless Steel
Stainless steel or other metal not readily attacked by cement paste
ASTM C490
Reference Bar Thermal Expansion (Max)
Low-expansion steel (e.g. Invar)
2.0 x 10^-6 /°C
ASTM C490
Scope of Standard
Mould for determination of linear shrinkage
Practice for Use of Apparatus for Determination of Length Change
ASTM C490
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Internal length of mould140 mm
Internal width of mould12.5 mm
Internal height of mould12.5 mm
General tolerance on dimensions± 0.2 mm
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 2 - Material
Clause 3 - Dimensions
Frequently Asked Questions4
What are the internal dimensions of the linear shrinkage mould?+
140 mm (length) x 12.5 mm (width) x 12.5 mm (height) as per Clause 3.1.
What material should the mould be made from?+
Brass or any other suitable non-corrodible metal of adequate strength, as specified in Clause 2.1.
What is the tolerance on the mould's dimensions?+
A tolerance of ±0.2 mm is permitted on all specified dimensions (Clause 3.1).
Which test method uses this mould?+
This mould is designed for the determination of linear shrinkage of soil as described in IS 2720 (Part 20).