IS 2720:1968 Part 14 is the Indian Standard (BIS) for methods of test for soils - part 14: determination of density of soil, field method (sand replacement method). Covers the field procedure for determining the in-situ bulk and dry density of natural or compacted soils using the sand replacement method. It is a critical quality control test used widely to verify the degree of compaction achieved in earthworks, road subgrades, and embankments.
Specifies the sand replacement method for determining the in-situ density of natural or compacted soils.
Field methods for soil density determination — sand replacement, core cutter, rubber balloon. Compaction acceptance.
| Reference | Value | Clause |
|---|---|---|
| Method 1 — sand replacement (small) | for fine-medium grained soils | Cl. 3 (small pouring cylinder, 100 mm dia) |
| Method 2 — sand replacement (large) | for soils with gravel content | Cl. 3 (large pouring cylinder, 200 mm dia) |
| Method 3 — core cutter | for cohesive soils, no boulders | Cl. 4 |
| Method 4 — rubber balloon | for variable soils | Cl. 5 |
| Method 5 — water displacement | for cohesive samples (lab/site) | Cl. 6 |
| Sand replacement — calibration sand | uniform 600 μm – 300 μm clean | Cl. 3.1.1 |
| Sand replacement — bulk density of sand | ≈ 1.4–1.6 g/cm³ (calibrated) | Cl. 3.3 |
| Core cutter — internal diameter | 100 mm | Cl. 4.1.1 |
| Core cutter — internal height | 127.3 mm (volume 1000 cm³) | Cl. 4.1.1 |
| Core cutter — wall thickness | 3 mm | Cl. 4.1.1 |
| Test hole depth (sand replacement) | ≥ 125 mm | Cl. 3.4 |
| Number of tests per layer (acceptance) | 1 per 1000 m² minimum | (IS 4082 + IRC SP 84) |
| Bulk density formula | γ = mass / volume | Cl. 3.7 / 4.4 |
| Dry density formula— w = moisture content | γd = γ / (1 + w) | Cl. 3.7 |
| Compaction acceptance — embankment | ≥ 95 % of MDD (modified Proctor) | (IRC SP 84) |
| Compaction acceptance — subgrade | ≥ 97 % of MDD | (IRC 36 + IRC SP 84) |
| Compaction acceptance — sub-base | ≥ 98 % of MDD | (MORTH § 401) |
| Standard test temperature | 27 ± 2 °C | Cl. 1.2 |
| Sample sealing (moisture content) | airtight container immediately | Cl. 3.6 / 4.3 |
| Reporting accuracy | γ to 0.01 g/cm³, w to 0.1 % | Cl. 3.7 |