Crushing Strength Test Procedure: How To Carry Out CST On Stone Aggregates
Crushing strength test is used for determining the strength or resistance of stone aggregates against crushing force. Stones used for construction purposes should have good resistance to crushing force in order to withstand the impact of load accurately.
In the procedure for conducting a crushing strength test, stone specimens usually of size 40mm x 40mm x 40mm are used. The stones are cut out of parent rock material. These stones should have their sides finely dressed, then placed in water for 3 days. This is to enable the specimens saturate by taking in water.
The saturated specimens should be provided with a layer of Plaster of Paris (POP) at the top and bottom, or a layer of 5mm plywood could be used. This is to uniformly distribute the applied load over the surface of the specimen.
Next, place the specimens in the Compression Testing Machine and test. Specimens should be loaded by the CTM at a rate of 14N/mm^2 per minute. Load specimen until failure occurs.
Note the crushing load of the specimen. The crushing strength could be found from the crushing strength thus:
Crushing Strength = crushing load (force)/Area over which load is applied.
At least three (3) specimens should be tested and average taken.
