IS 2720:1987 Part 18 is the Indian Standard (BIS) for methods of test for soils - part 18: determination of compaction properties (modified proctor). 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.
Key apparatus dimensions, compaction effort parameters, and procedural limits for the Modified Proctor soil compaction test.
| Reference | Value | Clause |
|---|---|---|
| Rammer Mass— Value as per Amd. No. 1 (Aug 1987). Original code stated 4.9 kg. | 4.89 kg | Cl. 2.2 |
| Rammer Height of Drop | 450 mm | Cl. 2.2 |
| Rammer Face Diameter | 50 mm | Cl. 2.2 |
| Number of Compaction Layers | 5 | Cl. 4.1 |
| Mould Capacity (Small)— For soils where <25% by mass is retained on the 20 mm IS Sieve. | 1000 cm³ | Cl. 2.1.1 |
| Mould Internal Diameter (Small) | 100 mm | Cl. 2.1.1 |
| Mould Internal Height (Small) | 127.3 mm | Cl. 2.1.1 |
| Blows per Layer (Small Mould) | 25 | Cl. 4.1 |
| Soil Fraction for Small Mould | Passing 20 mm IS Sieve | Cl. 3.1 |
| Mould Capacity (Large)— For soils where >25% by mass is retained on the 20 mm IS Sieve. | 2250 cm³ | Cl. 2.1.2 |
| Mould Internal Diameter (Large) | 150 mm | Cl. 2.1.2 |
| Mould Internal Height (Large) | 127.3 mm | Cl. 2.1.2 |
| Blows per Layer (Large Mould) | 56 | Cl. 4.1 |
| Soil Fraction for Large Mould | Passing 40 mm IS Sieve | Cl. 3.1 |
| Detachable Collar Height | 60 mm | Cl. 2.1.1 & 2.1.2 |
| Oven Drying Temperature— For determining water content. | 105 to 110 °C | Cl. 2.6 |
| Balance Accuracy (Soil Mass)— For 1000 cm³ mould. | 1 g | Cl. 2.5 |
| Balance Accuracy (Soil Mass)— For 2250 cm³ mould. | 5 g | Cl. 2.5 |
| Balance Accuracy (Water Content) | 0.01 g | Cl. 2.5 |
| Formula for Bulk Density (ρ)— M = Mass of compacted soil; V = Volume of mould. | M / V | Cl. 5.1 |
| Formula for Dry Density (ρd)— ρ = Bulk density; w = water content as a decimal. | ρ / (1 + w) | Cl. 5.2 |