DETERMINATION OF COMPRESSIVE STRENGTH OF BRICK

 

Apparatus:

ž  A compression testing machine, the compression plate of which shall have a ball seating in the form of portion of a sphere the center of which coincides with the center of the plate, shall be used.

ž  Preconditioning: Remove unevenness observed in the bed faces to provide two smooth and parallel faces by grinding. Immerse in water at room temperature for 21 hours. Remove the specimen and drain out any surplus moisture at room temperature. Fill the frog ( where provided ) and all voids in the bed face flush with cement mortar ( 1 cement, clean coarse sand of grade 3 mm and down ). Store under the damp jute bags for 24 hours followed by immersion in clean water for 3 days. Remove, and wipe out any traces of moisture.

Procedure:

Place the specimen with flat faces horizontal, and mortar filled face facing upwards between two 3-ply plywood sheets each of 3 mm thickness and carefully centred between plates of the testing machine. Apply load axially at a uniform rate of 14 N/mm* (140 kgf/cm2) per minute till failure occurs and note the maximum load at failure. The load at failure shall be the maximum load at which the specimen fails to produce any 1 further increase in the indicator reading on the testing machine.

 

NOTE - In place of plywood sheets plaster of Paris may be used to ensure a uniform surface for application of load.

 

Report:-

The report shall be as given below:

Compressive strength in N/mm2    =                 Maximum load at failure in N

                                                                      Average area of the bed faces in mm2