AASHTO T19 - Unit Weight and Voids in Aggregate

Summary

This instructional video demonstrates how to test the unit weight of aggregate, focusing on the process of compacting materials using three methods: rodding, jigging, and shoveling. It explains how to calibrate the equipment, prepare the material, and the specific techniques for each method depending on the size of the aggregate. The rodding method is used for smaller aggregates, jigging for larger ones, and shoveling is specified when required. Proper techniques are emphasized for leveling, avoiding segregation, and accurate weighing of the compacted material. The video serves as a guide for soil and aggregate technician certification procedures.

Takeaways

• 😀 Calibration is required at least once a year for the measurement equipment used in the procedure.
• 😀 The amount of material needed to start the procedure is approximately 125% to 200% of the required amount to fill the measure.
• 😀 There are three methods of compacting material in the measure: rodding, jigging, and shoveling.
• 😀 Rodding is used for aggregates with a maximum nominal size of 1.5 inches or less and involves three equal lifts with 25 rods per lift.
• 😀 In rodding, it is important not to strike the bottom of the measure on the first lift and to avoid penetrating into previous lifts on subsequent ones.
• 😀 Jigging is used for aggregates larger than 1.5 inches and up to 5 inches, involving 50 slaps (25 per side) with a 2-inch lift and hard slapping blows.
• 😀 Shoveling is only used when specified, and material must be discharged no more than 2 inches from the top rim of the measure to avoid segregation.
• 😀 During shoveling, it is important to work around the measure and avoid segregation as much as possible.
• 😀 After compaction, the material should be leveled, ensuring any projections above the rim balance with the voids below it.
• 😀 The weight of the filled measure should be recorded to the nearest 0.1 lb, and the empty measure's weight should also be recorded to the same precision.

Q & A

What is the purpose of calibrating the measure used for aggregate testing?

The measure needs to be calibrated at least once a year to ensure accurate volume measurement of the material being tested.

How much material is needed before starting the compacting process?

Approximately 125 to 200% of the amount required to fill the measure should be prepared before starting the compacting process.

What are the three methods of compacting the material in the measure?

The three methods are rodding, jigging, and shoveling.

When should rodding be used for compacting material?

Rodding is used for aggregates with a maximum nominal size of 1.5 inches or less.

What is the proper technique for rodding the material in the measure?

Rodding involves performing three equal lifts with 25 rods per lift. The first lift should avoid striking the bottom forcibly, while the second and third lifts should penetrate the lift being compacted but not the previous lift.

How should jigging be performed for compacting material?

For jigging, the material is lifted 2 inches on one side and allowed to fall with a hard slapping blow. The process should alternate between sides, with a total of 50 slaps (25 on each side).

When should shoveling be used in the compacting process?

Shoveling is only used when specified, and it involves continuously discharging material into the measure without being more than 2 inches away from the top rim.

What should be done to avoid segregation during the shoveling method?

To avoid segregation, it's important to discharge the material evenly around the measure while filling it.

How should the material be leveled after compacting?

After compacting, the material should be leveled at eye level to ensure any projections above the rim are balanced with voids below the top of the rim.

What is the importance of weighing the measure after leveling the material?

The measure should be weighed to the nearest 0.1 lb to determine the exact weight of the compacted material, with the empty measure also weighed to the nearest 0.1 lb for accurate results.