LimsPulse
Construction materials testing

Proctor Compaction Apparatus

A cylindrical mould and a rammer of fixed mass and drop height used to compact soil at different water contents and find its maximum dry density (MDD) and optimum moisture content (OMC).

  • Geotechnical testing
  • Road and highway construction
  • Railways and airports
  • Dams and embankments
  • Construction materials testing
Photo of a Proctor Compaction Apparatus
Photo: Zaher.Kadour, CC BY-SA 3.0 (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Check the rammer mass and drop height check and mould volume are in date.
  2. 2Weigh the empty mould with base plate.
  3. 3Prepare about 5 kg (1000 cm³ mould) of soil passing the specified sieve and air-dried.
  • Use the correct rammer for the test: light and heavy rammers look similar.
STAGE 2

Compacting

  1. 1Mix the soil with a measured amount of water (e.g. starting about 4–6% below the expected OMC for sandy soils, more for clays).
  2. 2Clamp the mould and collar to the base on a solid floor or concrete block.
  3. 3Place the first layer and give 25 blows from the full drop height, moving the rammer evenly over the surface.
  4. 4Repeat for the remaining layers so the final layer extends just into the collar.
  • Hold the guide vertical and let the rammer fall freely; do not push it down.
STAGE 3

Weighing and moisture

  1. 1Remove the collar, trim the soil level with a straight edge and weigh mould + soil.
  2. 2Extrude the soil and take a moisture sample from the centre.
  3. 3Break up the soil, add more water and repeat for at least five points spanning the peak.
  4. 4Oven-dry moisture samples at 105–110 °C and calculate water content.
STAGE 4

After testing

  1. 1Calculate bulk and dry density for each point and plot the compaction curve.
  2. 2Read MDD and OMC from the peak.
  3. 3Clean the mould, collar and rammer face.
In LimsPulse · Calibration Management

Keep every Proctor apparatus in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

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