How to calculate compressive strength of brick according to IS 3495
This article describes the test approach to determining the compressive strength of bricks. One can refer to IS: 5454:1976 for more information with regards to the test procedure. The dimensions for area calculation should be measured to nearest 1 mm.It should been sure before continue the test procedure that each of the tools and equipments used is calibrated. For guidance regarding to selection of specimen, IS 5454:1976 shall be refereed.
Tools and equipments required
Compression testing machine and the compression plate.
Preparing brick specimen for testing
To accomplish smooth and parallel surface, remove unevenness by grinding. For 24 hours, submerged the brick specimen to room temperature. Remove specimen and remove excess moisture. With cement mortor, fill the frog and gaps in bed faces. Wrap the specimen in wet jute bag for the period of 24 hours. After this again immerse the specimen in clean water for three days.After three days,remove the specimen and wipe out excess moisture on the surface.
Compressive test procedure
With frog facing upward,place the specimen between two to three plywood sheets. The thickness of each plywood sheet should be about three mm. Also make sure the placement of sheet to be in the centred between the plates. Now apply the load axially at uniform rate of 14 N / mm 2 per minute. The application of load will be continue till failure of sample occurs. Ensure the load at failure should be maximum which is indicated by no incremental value on dial gauge
Calculation of compressive strength
The compressive strength of bricks will be calculated by following formula
Compressive strength in N/mm2 = Maximum load at failure in N(kgf) / Average area of the bed faces in mm2