Question

Arrange the procedure steps in ascending order for a standard test of compression strength of a brick 

a- Test the sample by keeping the mortar filling face upwards and flat face horizontal in compression testing machine and note down the crushing load.

b- The bricks are stored under damp jute bags for 24 hours followed by immersion in clean water for 3 days

c- The frogs and all the voids in the bed face are filled with cement mortar 1:1 (1 cement, (1 clean coarse sand of grade 3 mm and down).

d- Then remove the specimens and drain out any surplus moisture at room temperature.

e- The bricks specimens are immersed in water at room temperature (250C to 290C) for 24 hours.

1. a, b, c, d, e
2. e, d, b, c, a
3. e, d, c, b, a
4. e, c, d, b, a

Answer 1

Correct Answer - Option 3 : e, d, c, b, a

Concept:

Compressive Strength of Bricks: 

• The compressive strength of bricks is the capacity of brick to resist or withstand under compression when tested on a Compressive testing machine [CTM].
• The Compressive strength of a material is determined by the ability of the material to resist failure in the form of cracks and fissures.

The procedure of test of compression strength of a brick : 

1. Three bricks are picked from the brick pouch and the unevenness on the brick faces is removed by grinding. 
2. Immerse the brick samples in the water for 24 hours at the temperature of 23-degree centigrade. 
3. Prepare the mortar by mixing the cement and sand at a ratio of 1:1.
4. Fill the frog with the mortar paste and allow to set the bricks in jute bags for the period of 24hrs.
5. Also, check for the voids on the brick surface. If there any fill the voids by flushing the mortar on them. 
6. Take out the bricks from bags and immerse them back in the water for 7 days to complete the hardening of mortar on the brick.
7. Allow the bricks to dry, before placing it on the compressive testing machine
8. Place the specimen flat-wise on the base of CTM, with mortar filled face upwards between the two flat plywood sheets.
9. Plywood sheets are used to hold the brick in the correct position while testing. 
10. Start the CTM and apply the load axially on the specimen at the rate of 14 N/mm² (140 kg/cm²) per minute till the brick starts breaking.
11. Repeat the same procedure with the leftover bricks
12. Note down the reading of each brick from CTM once the brick starts tearing.