To determine the maximum size of a given sample of coarse aggregate.

Lab Report: Determination of Maximum Size of Coarse Aggregate

Objective: To determine the maximum size of a given sample of coarse aggregate using sieve analysis.

Apparatus:

1. Standard set of sieves (e.g., 75 mm, 63 mm, 50 mm, 37.5 mm, 25 mm, 19 mm, 12.5 mm, 9.5 mm, 4.75 mm)
2. Weighing balance (accurate to 0.1 g)
3. Sieve shaker
4. Sample of coarse aggregate (as per ASTM C136 / AASHTO T27)
5. Brush for cleaning sieves
6. Tray for collecting material

Procedure:

1. Obtain a representative sample of coarse aggregate (about 5 kg) using the AST C702 method.
2. Weigh the total sample and record the weight (W).
3. Arrange the sieves in descending order, with the largest sieve on top and the smallest sieve at the bottom.
4. Place the sample on the top sieve and shake it using a sieve shaker for 10 minutes.
5. Weigh the material retained on each sieve and record the weight.
6. Calculate the percentage passing through each sieve using the
7. Identify the smallest sieve through which 100% of the aggregate passes. This is the maximum aggregate size.

Observations & Calculations: Tabulate the data as follows:

• The maximum aggregate size is the smallest sieve through which 100% of the aggregate passes.
• The nominal maximum size is the sieve just larger than the first sieve that retains some material.

Results:

• Maximum Aggregate Size = ____ mm
• Nominal Aggregate Size = ____ m= _____ mm

Conclusion: The experiment successfully determined the maximum size of the coarse aggregate sample. The results can be used in concrete mix design to ensure proper workability, strength, and durability of the concrete.

Precautions:

1. Ensure the sample is dry before testing.
2. Use proper sieving techniques and avoid overloading sieves.
3. Weigh the material accurately to minimize errors.
4. Clean the sieves properly to prevent clogging and inaccuracies.