This part of IS 4031 establishes the standard procedure for determining the compressive strength of hydraulic cement. It details the preparation of a 1:3 cement-standard sand mortar, casting into 70.6 mm cubes, compaction via a vibration machine, curing conditions, and testing under a compression testing machine.
Describes the procedure for determining the compressive strength of hydraulic cement mortar cubes at various ages.
Quick Reference Values
cement to sand ratio1:3 by mass
cube size70.6 mm
face area of cube5000 mm²
vibration speed12000 ± 400 vibrations per minute
vibration duration2 minutes
rate of loading35 N/mm²/min
test room temperature27 ± 2 °C
curing water temperature27 ± 2 °C
Key Formulas
Water quantity for mortar = (P/4 + 3.0)% of combined mass of cement and sand, where P is standard consistency
Compressive strength = Maximum load applied to cube / 5000 (Result in N/mm²)
Practical Notes
Always use Ennore standard sand conforming to IS 650 for mortar preparation to ensure repeatable results.
Moulds must be thoroughly cleaned and lightly oiled to prevent mortar adherence and ensure perfect cube edges.
Ensure the vibration machine is strictly calibrated to 12000 ± 400 RPM; improper compaction heavily skews strength results.