Fine Aggregate Angularity Test

Summary

This video demonstrates the Fine Aggregate Angularity (FAA) test, also known as the Uncompacted Void Content of Fine Aggregate test, which is essential for determining the workability of asphalt mixtures. The process includes calibrating the cylinder, preparing and sieving a sample, and performing the test in two trials to measure the void content. The procedure involves precise steps for weighing, mixing, and leveling the material to ensure accurate results. The final calculation is the average of the two trials, providing crucial data for assessing fine aggregate suitability in asphalt paving.

Takeaways

• 😀 The Fine Aggregate Angularity (FAA) Test measures the void content of fine aggregate, which affects the workability of asphalt mixtures.
• 😀 The test requires equipment such as a funnel, calibrated cylinder, straight edge, pan, balance, brush, and a spoon for stirring.
• 😀 The bulk specific gravity of the fine aggregate must be determined before conducting the test.
• 😀 The calibration process of the cylinder involves adding grease around the rim, filling with cooled water, and ensuring an airtight seal using a glass cover plate.
• 😀 A sample of 1,000 grams of fine aggregate is required for the test, which must be washed and dried before use.
• 😀 Sieves are used to separate the sample into prescribed fractions, which are then combined to create a final composite sample of 190 grams.
• 😀 The test involves filling the calibrated cylinder with the aggregate sample, leveling it, and striking off excess material to measure the volume accurately.
• 😀 Tapping the side of the cylinder helps consolidate the material and minimize material loss during the weighing process.
• 😀 After the first trial, the sample is remixed thoroughly, and the test is repeated to ensure consistency in results.
• 😀 The final result is calculated as the average of the two test trials, providing an assessment of the fine aggregate's angularity.
• 😀 The results of the FAA Test help in understanding the fine aggregate's suitability for use in asphalt paving mixtures.

Q & A

What is the primary purpose of the Fine Aggregate Angularity (FAA) test?

The primary purpose of the FAA test is to measure the void content of fine aggregate, which helps in assessing the workability of asphalt paving mixtures.

What is the significance of determining the bulk specific gravity of fine aggregate in the FAA test?

The bulk specific gravity of fine aggregate must be determined prior to the FAA test as it is required for the final calculations to assess the void content accurately.

What are the key components of the fine aggregate angularity apparatus?

The key components include a stand, funnel, calibrated cylinder, glass plate, straight edge, pan, balance, small brush, small pan or dish, and optionally a spoon for stirring the sample.

Why is it necessary to calibrate the cylinder before performing the FAA test?

Calibrating the cylinder ensures accuracy in the measurement of the water volume, which is critical for determining the precise weight of the sample and void content.

How is the volume of the cylinder determined during the calibration process?

The volume is determined by filling the cylinder with cooled, di-ionized boiled water until it overflows, then using a glass cover plate to create an airtight seal before weighing it.

What is the proper procedure for obtaining the test sample of fine aggregate?

The test sample is obtained by reducing the initial sample to 1,000 grams of minus number 4 material, which can be done through hand shaking or sieve analysis, followed by washing the sample over a number 100 or 200 sieve.

What role does the sieve analysis play in preparing the FAA test sample?

Sieve analysis helps to separate the sample into specific fractions, which are then combined in prescribed amounts to create the final composite sample for the FAA test.

What is the purpose of using the straight edge during the test procedure?

The straight edge is used to level the sample inside the funnel and to strike off the excess material above the rim of the cylinder after the sample has been poured in.

Why is it important to tap the side of the cylinder during the FAA test?

Tapping the side of the cylinder helps consolidate the material inside, reducing air pockets, and prevents the loss of material when transferring the cylinder to the balance.

How do you ensure the accuracy of the FAA test results?

To ensure accuracy, the test is run twice, with the sample being thoroughly mixed and remixed between trials. The average of the two test results is then used for final calculations.