Dry Density — Heavy Compaction Test
(Modified Proctor Test — IS 2720 Part 8)
Laboratory determination of the optimum moisture content (OMC) and maximum dry density (MDD) of soils using heavy (modified) Proctor compaction — for airport, runway, heavy industrial and expressway subgrade design.
What is the Dry Density — Heavy Compaction Test?
The Modified Proctor Compaction Test (Heavy Compaction) determines the OMC and MDD under a higher compaction energy of 2700 kJ/m³ — 4.9kg rammer, 450mm drop, 5 layers, 25 blows per layer. This simulates the heavier compaction equipment used on high-specification projects and produces a higher MDD (denser compaction) and lower OMC than the Standard Proctor test.
Conducted as per IS 2720 Part 8, the Modified Proctor test is specified for airport runways (AAI), expressways, heavy industrial facilities and any project where compaction equipment produces energy equivalent to or exceeding the modified effort. The resulting MDD and OMC are used to specify field compaction requirements and verify compliance per IS 2720 Part 28.
Dry Density — Heavy Compaction Test — Site Images
How the Dry Density — Heavy Compaction Test is Conducted
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1Sample PreparationSoil sieved through 20mm sieve. 5kg portions prepared at 5 different water contents spanning OMC.
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2Heavy CompactionSoil compacted in 1000ml mould in 5 equal layers, 25 blows per layer with 4.9kg rammer falling 450mm.
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3Water Content MeasurementRepresentative sample from each specimen dried at 105°C for water content determination.
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4Dry Density CalculationBulk density from mould mass and volume. Dry density = bulk density / (1 + w/100).
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5OMC, MDD & ReportCompaction curve plotted. OMC and MDD read from peak. Zero air voids curve plotted. NABL report within 3 days.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 2720 Part 8 | Methods of Test for Soils — Determination of Water Content-Dry Density Relation (Heavy Compaction) | Modified Proctor | Indian Standard |
| IS 2720 Part 28 | Methods of Test for Soils — Determination of Dry Density by Sand Replacement | Field Density Reference | Indian Standard |
| ASTM D1557 | Standard Test Methods for Laboratory Compaction Characteristics of Soil — Modified Effort | Modified Proctor | ASTM |
| IRC 36 | Recommended Practice for Construction of Earth Embankments for Road Works | Highway Earthwork | IRC |