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GATE 2016 CE (CE2) – Question 52

Geotechnical Engineering · Compaction and one-dimensional consolidation · 2 marks · Multiple choice

OMC-SP and MDD-SP denote the optimum moisture content and maximum dry density obtained from standard Proctor compaction test, respectively. OMC-MP and MDD-MP denote the optimum moisture content and maximum dry density obtained from the modified Proctor compaction test, respectively. Which one of the following is correct?

  1. OMC-SP < OMC-MP and MDD-SP < MDD-MP
  2. OMC-SP > OMC-MP and MDD-SP < MDD-MP
  3. OMC-SP < OMC-MP and MDD-SP > MDD-MP
  4. OMC-SP > OMC-MP and MDD-SP > MDD-MP Sand γsat = 19 kN/m3, γw = 9.81 kN/m3, φ ' = 32° c-φ soil γsat = 18.5 kN/m3, γw = 9.81 kN/m3 c' = 25 kN/m2, φ ' = 24° 1 m 4 m 3 m A γbulk = 16.5 kN/m3

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Correct answer: (B) OMC-SP > OMC-MP and MDD-SP < MDD-MP

Explanation

Modified Proctor testing applies greater compactive effort. For the conventional comparison on the same soil, this raises maximum dry density and lowers optimum moisture content. Therefore OMC-SP>OMC-MP while MDD-SP<MDD-MP, matching **B**.