Dry Density — Light Compaction Test
(Standard Proctor Test — IS 2720 Part 7)
Laboratory determination of the optimum moisture content (OMC) and maximum dry density (MDD) of soils using standard Proctor compaction — the reference compaction standard for earthworks and road construction.
What is the Dry Density — Light Compaction Test?
The Standard Proctor Compaction Test (Light Compaction) determines the relationship between water content and dry density of soil under a standard compaction effort of 2.6 kJ/m³. Soil is compacted in a 1000ml mould using a 2.6kg rammer dropped from 310mm height in 3 layers, 25 blows per layer. The test produces a compaction curve (dry density vs water content) whose peak defines OMC and MDD.
Conducted as per IS 2720 Part 7, the Standard Proctor test is the most widely used compaction reference in India for roads, embankments, backfill and earthworks. The MDD and OMC are used to specify the required field compaction — typically 95–100% of MDD — and as the basis for field density acceptance per IS 2720 Part 28 (sand replacement method).
Dry Density — Light Compaction Test — Site Images
How the Dry Density — Light Compaction Test is Conducted
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1Sample PreparationSoil sieved through 20mm sieve. Approximately 3kg soil prepared for each of 5 test points at different water contents.
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2CompactionSoil compacted in 1000ml mould in 3 equal layers, 25 blows per layer with 2.6kg rammer falling 310mm.
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3Water Content MeasurementRepresentative sample from each compacted specimen dried in oven at 105°C for moisture content.
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4Dry Density CalculationBulk density = mass of compacted soil / mould volume. Dry density = bulk density / (1 + w/100).
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5OMC, MDD & ReportDry density vs water content plotted. OMC and MDD read from peak of curve. NABL report within 3 days.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 2720 Part 7 | Methods of Test for Soils — Determination of Water Content-Dry Density Relation (Light Compaction) | Standard Proctor | Indian Standard |
| IS 2720 Part 28 | Methods of Test for Soils — Determination of Dry Density by Sand Replacement | Field Density | Indian Standard |
| IRC 36 | Recommended Practice for Construction of Earth Embankments for Road Works | Highway Earthwork | IRC |
| ASTM D698 | Standard Test Methods for Laboratory Compaction Characteristics of Soil — Standard Effort | Standard Proctor | ASTM |