To determine the compressive strength of bricks
Compression testing machine ,the compression plate of which shall have ball seating in the form of portion of a sphere center of which coincides with the centre of the plate.
Fig: Compression Testing Machine
Three numbers of whole bricks from sample collected should be taken .the dimensions should be measured to the nearest 1mm
Remove unevenness observed the bed faces to provide two smooth parallel faces by grinding .Immerse in water at room temperature for 24 hours .Remove the specimen and drain out any surplus moisture at room temperature. Fill the frog and all voids in the bed faces flush with cement mortar (1 cement,1 clean coarse sand of grade 3mm and down). Store it under the damp jute bags for 24 hours filled by immersion in clean water for 3 days .Remove and wipe out any traces of moisture.
(I) Place the specimen with flat face s horizontal and mortar filled face facing upwards between plates of the testing machine.
(II) Apply load axially at a uniform rate of 14 () per minute till failure occurs and note maximum load at failure.
(III) The load at failure is maximum load at which the specimen fails to produce any further increase in the indicator reading on the testing machine.
The average of result shall be reported.
Maximum compressive strength =
Contact area =
Maximum expected load =
The range to be selected is …………………
Average compressive strength of the given bricks =…………..
Speciation of Common Clay Building Bricks
Dimensions: The standard size of clay bricks shall be as follows
Classification: The common burnt clay shall be classified on the basis of average compressive strength as given in table.
Average compressive strength
Not less than