The digital compression testing machine is used to determine the compressive strength of cube and cylinder (i.e. hardened concrete).
Procedure as per IS 516 – Methods of tests for strength of concrete
1. Keep the specimen to be tested centrally on the clean lower platen so that small clearance is left between the upper platen and the top the specimen under test.
2. Close the pressure release valve.
3. Make the digital display to read “Zero” by adjusting the zero knob.
4. Put the display unit on “Peak Hold” mode to hold the maximum load reading.
5. Start applying the load at the specified pace rate, which could be maintained by adjusting the slow fast knob.
6. If the pace rate is on higher side the indicator displays red colour and the pace rate is on lower side the indicator will display yellow colour.
7. If the pace rate is exactly equal to set rate then the indicator will display green colour.
8. As soon as sample fails, release the pressure slowly by opening valve.
9. The digital display will be holding the maximum load reading at which sample has failed. Note down the pattern of failure and calculate the compressive strength in N/mm2 or kg/cm2.
10. Pace rate for 15 cm cube is 5.15 kN/s.
11. Before starting another test, clean the lower platen and bring the digital display to “Zero” position by depressing the “Reset” switch.