Aim:

This lab activity aims to determine the compressive strength of cement by conducting compression tests on cement cubes using a compression testing machine.

Theory:

Compressive strength is an essential property of cement as it determines the load-bearing capacity of structures made from cement. The compressive strength of cement is the maximum compressive load that cement cubes of a specified size can withstand before they fail. 

The compressive strength of cement is influenced by several factors such as the proportion of cement, water, and aggregates used in concrete, the curing conditions, and the age of the concrete. The compressive strength of cement is usually determined by conducting compression tests on cement cubes.

Apparatus and Materials Required:

• Compression testing machine
• Water for curing
• Weighing balance
• Trowel
• Tamping rod
• Non-porous plates
• Vernier calliper
• Gloves

Procedure:

1. Prepare the cement cubes by mixing cement, water, and aggregates in the specified proportion.
2. Fill the cement mixture in the cube moulds and tamp the mixture using a tamping rod.
3. Level the top of the cubes with a trowel and cover them with non-porous plates.
4. Cure the cubes in water for 7, 14, and 28 days respectively.
5. After the curing period, remove the cubes from the water and wipe them with a damp cloth.
6. Measure the dimensions of each cube using a vernier calliper.
7. Place the cube on the compression testing machine and apply a gradually increasing load until the cube fails.
8. Record the maximum load that the cube can withstand before it fails.
9. Repeat the test for all the cubes and record the results.

Results:

1. Calculate the compressive strength of cement for each cube using the formula:

2. Compressive strength = Maximum load applied / Area of the cube

3. The area of the cube can be calculated using the formula:

4. Area of cube = Length x Breadth

5. Tabulate the results obtained for each cube and calculate the average compressive strength of cement for each curing period. Plot a graph of compressive strength against the curing period.

Precautions:

• Wear gloves while handling cement as it can cause skin irritation.
• Ensure that the compression testing machine is calibrated before conducting the test.
• Make sure that the dimensions of the cubes are accurately measured using a vernier calliper.
• Do not disturb the cubes while they are curing in water.
• Use non-porous plates to cover the cubes to prevent moisture loss during curing.
• Ensure that the testing machine is calibrated before performing the test.
• Use safety goggles and gloves while handling the cement samples and during the test.
• Avoid applying sudden or excessive loads on the samples, which may result in premature failure.
• Ensure that the cement cubes are stored in a cool and dry place before testing.

Conclusion:

The compressive strength of cement is an important parameter that indicates the ability of the adhesive to withstand compressive loads. The test procedure outlined above provides a reliable and accurate method for determining the compressive strength of cement. The results obtained can be used to evaluate the quality of cement and to ensure that it meets the desired specifications.

The determination of the compressive strength of cement is a crucial test that should be performed regularly to ensure the quality and reliability of cement. By following the procedure outlined above and taking the necessary precautions, accurate and reliable results can be obtained.