Reviewed by Er. Inderjit Sharma (Retd.), Punjab PWD
What is this test? It finds the dry density of soil in the field, right where it has been compacted. You dig a small hole, weigh the soil you removed, and find the hole’s volume by filling it with sand of known density.
Why it matters: it tells you whether an embankment, subgrade or backfill has been compacted enough. The field dry density is compared with the maximum dry density (MDD) from the lab Proctor test.
This guide follows IS 2720 (Part 28), using the large pouring cylinder (for fine, medium and coarse-grained soils).
The Idea in One Picture
Apparatus Required
Sand pouring cylinder
Holds the sand; a shutter (valve) controls the flow; the cone sits below.
Calibrating container
About 200 mm diameter, 250 mm deep; used to find the density of the sand.
Metal tray with hole
Placed on the ground; guides the size of the hole.
Digging tools
Scraper, dibber or spoon to dig the hole neatly.
Balance (15 kg, 1 g)
Weighs the cylinder, the sand and the dug-out soil.
Clean, uniform sand
Dry sand passing the 1 mm sieve and retained on the 600 micron sieve.
The Sand Pouring Cylinder
Procedure
Part A: Calibrate the Cylinder (find the density of the sand)
- Sand in the cone: fill the cylinder with sand and weigh it (W1). Place it on a flat glass plate, open the shutter, let the sand fill the cone, close the shutter and weigh again. The loss is the sand that fills the cone (W2).
- Volume of the container (V): find it by filling the calibrating container with water and weighing (1 g of water = 1 ml).
- Sand in the container: refill the cylinder to the same mass W1. Place it on the calibrating container, open the shutter until the sand stops, close it and weigh what’s left (W3).
- Sand in the container: Wa = W1 − W3 − W2. Bulk density of sand: γs = Wa ÷ V.
- Repeat at least three times and use the average.
Part B: Field Test
- Clean and level a small area (about 450 mm square) of the compacted layer. Place the tray on it.
- Dig a hole through the hole in the tray, about 200 mm wide and as deep as the compacted layer (not more than about 250 mm). Collect all the loose soil in a closed container.
- Weigh the soil removed (Ww). Keep a sample for water content (w) as per IS 2720 (Part 2).
- Remove the tray. Fill the cylinder to the same mass W1, place it over the hole, open the shutter until the sand stops flowing, close it and weigh what’s left (W4).
- Sand in the hole: Wb = W1 − W4 − W2.
Calculation
Report bulk and dry densities in g/cm³ to two decimal places.
Try It: Field Density Calculator
Enter your weights in grams. The values filled in are a worked example.
A. Calibration
B. Field test
Field Record Format
Use this format at site (scroll sideways on mobile).
| Item | Test 1 | Test 2 | Test 3 |
|---|---|---|---|
| Chainage / location | |||
| Offset / layer | |||
| Depth of hole (mm) | |||
| Ww: soil from hole (g) | |||
| W1: cylinder + sand before (g) | |||
| W4: cylinder + sand after (g) | |||
| Wb = W1 − W4 − W2 (g) | |||
| Volume of hole Vh (cm³) | |||
| Bulk density γb (g/cm³) | |||
| Water content w (%) | |||
| Dry density γd (g/cm³) | |||
| MDD (g/cm³) | |||
| Degree of compaction (%) | |||
| Required (%) / Accepted? |
Precautions
🏖️ Right sand
Use clean, dry, uniformly graded sand. Damp sand flows unevenly and changes its density.
⚖️ Same starting weight
Fill the cylinder to the same mass W1 for calibration and for every field test.
🕳️ Neat hole
Don’t let the hole widen at the bottom or leave loose soil inside. Collect every crumb of excavated soil.
🚜 No vibration
Keep rollers and vehicles away while sand is flowing; vibration packs the sand and gives a wrong volume.
Practical Tips for Site Engineers
1. Typical Compaction Requirements
| Layer | Minimum compaction |
|---|---|
| Embankment | 95% of MDD |
| Subgrade and shoulders | 97% of MDD |
MDD from heavy compaction, IS 2720 (Part 8), as per MoRTH specifications. Always follow your contract specification.
2. Which Field Method to Use
Sand replacement
For granular, gravelly or stony soils, GSB and WMM, where a core cutter can’t be driven.
Core cutter
For soft, cohesive soils without stones; quicker, but not for gravel.
Nuclear density gauge
Very fast for many readings; check it regularly against sand replacement results.
3. Good Site Habits
- Test every layer before the next one is laid. Once covered, a poorly compacted layer can’t be checked or fixed easily.
- Dig the full layer depth: the bottom of a layer is usually the least compacted. A shallow hole gives a falsely high result.
- Choose spots at random across the width, including near edges, not only where the roller passed most.
- Recalibrate the sand for every new batch, and whenever it may have taken up moisture. Store it dry in closed bags.
- Get water content quickly: seal the soil sample at once. A rapid moisture meter helps for quick decisions; confirm with the oven method.
- Low result? Check the moisture first: soil much drier or wetter than OMC won’t compact well. Adjust water, then add roller passes and retest.
- Use the right MDD: compare with the Proctor result for the same soil or borrow area. A different soil needs its own MDD.
Key Takeaways
- Dig a hole, weigh the soil, and fill the hole with calibrated sand to find its volume.
- Calibrate first: cone sand (W2) and sand density γs = (W1 − W3 − W2) ÷ V; average of 3.
- Hole sand Wb = W1 − W4 − W2; γb = Ww ÷ (Wb/γs); γd = γb ÷ (1 + w/100).
- Degree of compaction = γd ÷ MDD × 100.
- On site: typically 95% for embankment, 97% for subgrade; test full layer depth; keep the sand dry and recalibrated.
References: IS 2720 (Part 28): Determination of Dry Density of Soils In-place by the Sand Replacement Method; IS 2720 (Part 2): Water Content; IS 2720 (Part 8): Heavy Compaction; MoRTH Specifications for Road and Bridge Works (Section 300).