How to check Compressive Strength 

Universal Strength Machine

  • The machine consists of an oil reservoir, movable ram, plug-in coupling low & high-pressure gauges to read 0 to 1.600gms/cm and 0 to 13 kg/cm compression strength respectively, loading piston connecting to threaded shaft and wheel, funnel with a special connection, a bottle of oil. A pair of compression pads are supplied with the machine.

Pre Setting

  • Place the machine on the planned platform. Rotate the wheel anti-clockwise for bringing the piston assembly to the reservoir end. Remove the cap on the plug in the coupling. 
  • To fill the oil in it, press the funnel with a special connection in the plug in the coupling. So that it is locked. Fill the funnel to half its capacity by hydraulic oil supplied with the machine. 
  • Some quantity of oil will enter the reservoir. push the movable ram inside to remove the air inside the reservoir (air bubbles will be seen coming out through the oil in the funnel) make the level of the oil in the funnel and repeat the procedure till all the air from the reservoir is expelled out and oil is filled in the reservoir.
For more detail watch this video
  • Push the movable ram completely, in turn, the knurled ring of the plug-in coupling anti-clockwise to release the lock and pull out the funnel. Collect the oil remaining in the funnel, in the oil container, a select pressure gauge (L-Low pressure gauge, H- High-pressure gauge) L is used for green strength, and H is used for dry strength, insert the same in the plugin coupling and press it to lock. The red pointer is also available in the gauge for actual reading. Rotate the knob on the glass of the gauge anti-clockwise to bring the red idle pointer to touch the gauge needle.


  • Insert the compression pads in the respective position. Prepare the standard sand specimen of diameter 50 MM X 50MM height. Place the specimen between the compression pads so that the plan surfaces of the specimen touch against the pads.
  • Rotate the wheel clockwise until the load starts Appling on the specimen. This will be seen by the movement of the pressure gauge needle and then uniformly at about 16 Rpm, till the specimen collapses.
  • The red pointer’s main work moves with a black needle. As soon as the sample collapses the needle returns while the red pointer remains at the maximum reading before collapses of the specimen. To read compression strength on the scale (C.S. Scale), indicated by the idle pointer.
  • Take a minimum of three readings from the sample batch and take the average.

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