LimsPulse
Construction materials testing

Compression Testing Machine (CTM)

A rigid hydraulic press that crushes concrete cubes, cylinders and cement mortar cubes at a controlled loading rate and records the maximum load. The basic instrument of every concrete and cement lab.

  • Construction materials testing
  • Ready-mix concrete plants
  • Cement plants
  • Precast concrete
  • Infrastructure and road projects
  • Academic and research labs
Photo of a Compression Testing Machine (CTM)
Photo: Mohammad Hijjawi, CC BY-SA 4.0 (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 force verification certificate is in date and the machine is labelled with its class and verified range.
  2. 2Clean both platens and wipe off grit or old concrete fragments.
  3. 3Take the specimens out of the curing tank just before testing and keep them wet; wipe off surface water and grit.
  4. 4Measure each cube's dimensions to the nearest mm (or 0.1 mm for cylinders) and record its mass if density is required.
  • Do not test a specimen whose expected failure load is below the lower limit of the verified range of the selected range.
STAGE 2

Setting up

  1. 1Select the specimen type (cube / cylinder / mortar cube) and enter its dimensions so the controller calculates the area.
  2. 2Set the pace rate from the standard, e.g. about 14 N/mm²/min for concrete cubes (IS 516) or about 35 N/mm²/min for 70.6 mm mortar cubes (IS 4031 Part 6).
  3. 3Fit spacers so that the gap above the specimen is small, then place the cube centrally with a cast face upwards.
  4. 4Lower the upper platen (or raise the ram) until it just touches the specimen, letting the spherical seat align.
  • Never put the trowelled (top) face of a cube against a platen; it is not flat enough.
STAGE 3

Testing

  1. 1Close the safety guard and start the test.
  2. 2Watch that the load rises smoothly at the set rate without shocks.
  3. 3Let the controller detect failure and stop; record the peak load.
  4. 4Inspect and record the failure pattern; photograph unusual failures.
  • Stand clear of the platen area during loading; specimens can burst violently, especially high-strength concrete.
STAGE 4

After testing

  1. 1Release pressure and retract the ram fully.
  2. 2Remove broken concrete and sweep the platens and guard.
  3. 3Calculate strength = load ÷ area and the average of the set (usually three cubes).
  4. 4Record results with specimen ID, age, date cast and machine ID in the register or LIMS.
In LimsPulse · Calibration Management

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

See how