---
title: "Field compaction methods; Proctor curves"
subject: "Soil Mechanics"
chapter: 5
key: "semester_4/soil_mechanics:field-compaction-methods-proctor-curves"
source: https://www.bctengineer.com/q/semester_4/soil_mechanics/field-compaction-methods-proctor-curves
site: BCT Engineering
---

# Field compaction methods; Proctor curves

Soil Mechanics · Chapter 5: Soil Compaction

- Asked in: 2075 Bhadra, 2 marks
- Video: [Example and Solution of Soil Compaction Curve](https://www.youtube.com/watch?v=OHtKNe3WWZc) — Soil Mechanics
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/soil_mechanics/field-compaction-methods-proctor-curves
- Whole chapter: https://www.bctengineer.com/md/semester_4/soil_mechanics/chapter-5

## Question

Write down the names of the different methods of compaction carried out in the field. Draw compaction curves for the Standard Proctor Test and Modified Proctor Test.

## Short answer

Field methods include tamping, smooth-wheel rolling, sheep-foot rolling, pneumatic-tyred rolling, vibratory rolling, and dynamic compaction. The Modified Proctor curve lies above and left of the Standard Proctor curve, giving higher maximum dry density at lower optimum moisture content.

## Answer

#### Field compaction methods
1. Tamping (rammers)
2. Smooth-wheel (static) rolling
3. Sheep-foot (tamping foot) rolling
4. Pneumatic-tyred rolling
5. Vibratory rolling
6. Dynamic compaction (heavy tamping) and vibroflotation (for deep layers)

#### Compaction curves: Standard and Modified Proctor
The Modified Proctor test uses much more energy (4.5 kg hammer, 450 mm drop, 5 layers, 25 blows each) than the Standard Proctor test (2.5 kg hammer, 300 mm drop, 3 layers, 25 blows each), so it gives a higher MDD at a lower OMC.

```text
 γd
  |                                   ZAV line
  |       .--*--.  Modified (MDD2)    .
  |      /   :   \                   .
  |     /    :    \                 .
  |    /     :  .--*--.  Standard  .
  |   /      :  /  :   \ (MDD1)   .
  |  /       : /   :    \        .
  +----------+-----+---------------------- w
           OMC2  OMC1
```
Note: the peak of the Modified Proctor curve is higher and to the left (MDD$_2$ > MDD$_1$, OMC$_2$ < OMC$_1$). Both curves lie below and to the left of the ZAV line, and they come closer together on the wet side.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is a field compaction method?
   A. Sand replacement
   B. Hydrometer
   C. Sheep-foot rolling
   D. Triaxial testing
   Answer: C. Others are tests. (Key point: Field methods)

2. Compared with Standard Proctor, Modified Proctor gives:
   A. Higher OMC and MDD
   B. Lower MDD, higher OMC
   C. Same MDD
   D. Higher MDD, lower OMC
   Answer: D. More energy raises MDD and reduces OMC. (Key point: Modified Proctor)

3. Modified Proctor uses how many layers?
   A. 5
   B. 2
   C. 10
   D. 3
   Answer: A. Standard uses 3 layers, modified 5. (Key point: Layers)

## Related in Soil Mechanics

- [Compaction test: curve, MDD, OMC, RC](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Acompaction-test-curve-mdd-omc-rc) — Soil Mechanics, chapter 5, asked 2×
- [Compaction test, RC and saturation](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Acompaction-test-curve-saturation-degree) — Soil Mechanics, chapter 5, asked 2×
- [Road compaction specification, sand cone](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aroad-compaction-sand-cone-check) — Soil Mechanics, chapter 5
- [Compaction curves of sand and clay](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Acompaction-sand-vs-clay) — Soil Mechanics, chapter 5
- [ZAV; field compaction precautions](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Azero-air-void-field-precautions) — Soil Mechanics, chapter 5
- [Embankment 95% compaction, 950 cc mould](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aembankment-95-compaction-950cc-mould) — Soil Mechanics, chapter 5

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