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Field compaction methods; Proctor curves

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.

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.

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.

 γd
  |                                   ZAV line
  |       .--*--.  Modified (MDD2)    .
  |      /   :   \                   .
  |     /    :    \                 .
  |    /     :  .--*--.  Standard  .
  |   /      :  /  :   \ (MDD1)   .
  |  /       : /   :    \        .
  +----------+-----+---------------------- w
           OMC2  OMC1

Note: the peak of the Modified Proctor curve is higher and to the left (MDD2_2 > MDD1_1, OMC2_2 < OMC1_1). Both curves lie below and to the left of the ZAV line, and they come closer together on the wet side.

✓ Answer checked by Claude Opus 5.5 (high effort)

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