Compressive Strength test on Bricks
Compressive Strength test on bricks are carried out to determine the load carrying capacity of bricks under compression with the help of compression testing machine .
It is important to know the compressive strength of bricks to check for its suitability for construction.
Contents 🧱
1) Compressive strength of brick
2) Formula to calculate the compressive strength
3) Classification
Compressive Strength of Bricks :-
Is the capacity of brick to resist or withstand under compression when it tested on machine.
Compressive strength of any object is determined by the ability of the material to resist failure in form of cracks.
Procedure for test :-
* Take random 5-6 bricks and immerse them in water for 1 day ( means 24 hours ) at room temperature. (20-22 °C)
* After 24 hours, take them out, allow them to drain and then clean the surplus water.
* Now, fill their frogs by a layer of standard 1:1 mortar. then store minimum 24 hours for set the mortal
* Take the bricks out of the water, then allow water to drain and then remove surplus water. and when surface dry, all brick tested for compressive strength individually.
* Then place the brick between the sheets is placed in bricks testing machine and then load is applied axially and at a uniform rate of 140 kg/cm^2/min.
* Note the reading (Load) at which brick fails.
* Then we calculate the mean of all compression strength of bricks value.
Formula :-
Compressive Strength :- Load N/cross-sectional area.mm^2
Observations :
Contact area (top face Area) = .... m^2
Max Load at which the specimen [brick] starts breaking = ...N
For Ex :-
The Standard size of brick is 190mm x 90mm x90mm
Area = length x width =190 x 90 = 17,100 sq.mm
Support the max load at which the Brick starts cracking = 589 KN
As per formulae,
Compressive strength of calculated bricks =589x1000/17,100=34.4N/mm^2
Bricks are Classified as :-
* Bricks are mainly classified into two categories.
1) Burnt Bricks or pucca bricks.
2) Sun-dried bricks or kacha bricks.
And burnt bricks or pucca Bricks are further classified as :
*First class bricks.
*second calss bricks.
*third class bricks.
*Overburnt bricks or jhama bricks.
#On the basis of Compressive Strength bricks are classified as
1 First Class Brick : The brick which has a compressive strength of 10N/mm^2 is called as a First class brick
2 Second Class Brick : The brick with compressive strength of 7N/mm^2 is called as a Second Class Brick.
3 Third Class brick : The brick which we use for building has a compressive strength of 3.5N/mm^2
4 Overburnt Brick: The sun Dried brick has a compressive strength of 1.5N/mm^2 to 2.5N/mm^2
Classification as per ISI : 1077-1976
common burnt clay bricks are classified on the basis of their average compressive strength.
Each class of bricks is further subdivided into two sub-classes A and B based on tolerances and shapes e.g. brick of classification 35 is further sub-classified as 35A and 35B and so on.
* Bricks of Sub-class A shall have smooth faces, sharp edges and corners and uniformity in color.
* Sub- class B may be slightly have rounded edges.
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