This test method covers the determination of the relationship between the moisture content and dry density of soils using heavy compaction (Modified Proctor test). It is essential for determining the Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) for earthworks and pavement subgrades.
Specifies the modified Proctor test for determining the moisture-density relationship of soils for higher compaction energy.
Quick Reference Values
Rammer weight4.9 kg
Rammer drop height450 mm
Number of compaction layers5
Blows per layer (1000 cc mould)25
Blows per layer (2250 cc mould)56
Small mould volume1000 cc
Large mould volume2250 cc
Key Formulas
Dry Density (yd) = y / (1 + w/100) — where y is bulk density and w is moisture content in percent
Practical Notes
Ensure the soil is mixed thoroughly with water and allowed to mature/cure before testing to ensure uniform moisture distribution.
Use the larger 2250 cc mould if the soil contains a significant proportion of coarse material (more than 20% retained on the 4.75 mm sieve).
Take representative soil samples for moisture content determination immediately after extracting the compacted specimen to avoid moisture loss.