How to Determine the Compressive test of Bricks

Compression Testing Machine

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.

Compression testing machine

Compression Testing Machine

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 N/mm(square) 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.

Calculation :

Compressive Strength = Maximum load at failure / Average Area of Bed face.

The average of result shall be reported.

Range Calculation

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

Length (mm)


Width (mm)


Height (mm)


190 90 90
190 90 40


Classification: The common burnt clay shall be classified on the basis of average compressive strength as given in table.

Class Designation




Average compressive strength


Not less than




Less than




350 35 40
300 30 35
250 25 30
200 20 25
175 17.5 20
150 15 17.5
125 12.5 15
100 10 12.5
75 7.5 10
50 5 7.5
35 3.5 5

About The Author

Author: Civil Engineer

Hello, My self Neelmani, A Civil Engineer. Presently I am working with Indian Railway. An Affiliate Member of ASCE "American Society of Civil Engineers". B.Tech in Civil Engineering from MIT Muzaffarpur and Diploma in Railway from IPWE as well as Civil Engineering from Govt. Polytechnic Muzaffarpur.

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