This part of IS 4031 specifies the standard testing procedure for determining the drying shrinkage of hydraulic cement using 25x25x250 mm mortar prisms. It outlines the preparation, curing conditions, and exact methods for measuring length changes using a comparator.
Describes the procedure for determining the drying shrinkage of hydraulic cement mortar.
Quick Reference Values
Test specimen dimensions25 x 25 x 250 mm
Effective gauge length250 mm
Room temperature27 ± 2°C
Relative humidity of testing room65 ± 5%
Minimum relative humidity for initial curing90%
Number of specimens required3
Key Formulas
Drying Shrinkage (%) = [(L1 - L2) / G] × 100 — where L1 is initial length, L2 is final length, G is effective gauge length (250 mm)
Practical Notes
Ensure gauge studs are perfectly clean and aligned during moulding to avoid measurement errors in the length comparator.
Maintain the relative humidity of the testing room strictly at 65 ± 5%, as humidity directly affects drying shrinkage results.
Measurements should be taken rapidly to prevent thermal expansion caused by handling the specimen with bare hands.