Aim:

The aim of this lab activity is to determine the compressive strength of bricks using a compression testing machine. The compressive strength of bricks is an important property that is used to evaluate the load-bearing capacity of masonry structures.

This lab activity will help students understand the significance of compressive strength testing of bricks and provide hands-on experience in performing the test.

Theory:

Bricks are commonly used building materials. They are made by firing clay or a mixture of clay and other materials in a kiln. The compressive strength of a brick is the maximum load that it can withstand before it undergoes failure.

The compressive strength of bricks depends on various factors. These factors include – the quality of raw materials, manufacturing process, and firing temperature. The compressive strength of bricks is usually measured in N/mm2 or MPa.

Apparatus and Materials Required:

The following apparatus and materials are required for performing the compressive strength test on bricks:

1. Compression testing machine
2. Bricks (minimum of 5)
3. Water
4. Sieve (4.75 mm)
5. Vernier calipers
6. Graduated cylinder
7. Steel plate
8. Jolting apparatus
9. Balance

Procedure:

The following steps should be followed to perform the compressive strength test on bricks:

1. Take 5 bricks and immerse them in water for 24 hours to saturate them.
2. Clean the surface of each brick to remove any loose particles or dust.
3. Place the steel plate on the base of the compression testing machine.
4. Place the brick on the steel plate with the flat surface facing upwards.
5. Align the brick in the center of the compression testing machine and adjust the plate of the machine so that it is in contact with the top surface of the brick.
6. Apply a load on the brick at a rate of 14 N/mm2 per minute until it undergoes failure.
7. Record the maximum load that the brick can withstand before it fails.
8. Repeat the above steps for the remaining bricks.
9. Calculate the average compressive strength of the bricks using the formula: Compressive strength = Maximum load / Area of the face of the brick

Results:

The results of the compressive strength test on bricks can be presented in the form of a table and graph. The table should include the following details:

1. Serial number of the brick
2. The maximum load that the brick can withstand before failure
3. Area of the face of the brick
4. Compressive strength of the brick

The graph should show the compressive strength of each brick on the y-axis and the serial number of the brick on the x-axis. The average compressive strength of the bricks can be calculated by taking the mean of the individual compressive strengths.

Precautions:

The following precautions should be taken while performing the compressive strength test on bricks:

1. The compression testing machine should be calibrated before use to ensure accurate results.
2. The bricks should be soaked in water for at least 24 hours to ensure saturation.
3. The surface of the brick should be cleaned properly to remove any loose particles or dust.
4. The plate of the compression testing machine should be adjusted properly to ensure that it is in contact with the top surface of the brick.
5. The load should be applied at a uniform rate of 14 N/mm2 per minute.
6. The bricks should be handled carefully to avoid any damage before and during the test.

Conclusion:

The compressive strength test on bricks is an important laboratory activity that provides insight into the load-bearing capacity of masonry structures. The test is carried out using a compression testing machine and a minimum of 5 bricks.

The results of the test are presented in the form of a table and graph, which helps in analyzing the strength of the bricks. The lab activity also helps in understanding the significance of the test, the factors affecting the compressive strength of bricks, and the precautions that need to be taken during the test.