Unit Weight & Voids in Aggregate

Unit Weight & Voids in Aggregate

Introduction
This lab explores ASTM C29, Standard Test Method for Bulk Density (“Unit Weight”) & Voids in Aggregate.   In the lab an analysis of a fine and course aggregate was conducted in order to determine the unit weight in a compacted and loose state. The lab also determined the voids in fine and coarse aggregate separately, along with the voids of a   combined mixture of fine and coarse material. The main objective of the lab is to calculate the unit weight levels which are necessary for selecting proportions for concrete mixtures.   A secondary objective was to have the ratio of coarse to fine aggregate in the mixture be as close to 50/50 as possible.
Test Procedures
Apparatus and Materials Requirements
1.   (1) Digital scale that was readable to 0.1g.
2.   (2) Flat pyrex 13”x9” dish
3.   (1) tamping rod- a round, straight steel rod, 5/8 in. in diameter and approximately 24 in. in length, having one end rounded to a hemispherical tip of the same diameter as the rod.
4. (1) Measure-   a cylindrical metal watertight measure ( nominal 1/3 ft3 for coarse aggregate and 1/10 ft3 for fine aggregate)
5. (1) drying oven capable of 250°F
6. (1) metal scoop
7. (1) Large metal tray
8. (1) large bulb dropper
9. (1) pair of oven protective gloves
10. (1)large metal spoon
11. (1) nylon brush
12. Coarse aggregate oven dried at 250°F and then cooled to room temperature
13. Fine aggregate oven dried at 250°F and then cooled to room temperature
Note: The sample size of the two aggregates should be approximately 2 times the amount it would take to fill the measure.

Procedure
Measure Calibration
1. Determine the weight of the dry measure.
2. Fill the measure completely full with water and determine the weight of the measure plus water.
3. Calculate the weight of the water by taking the difference of (1) and (2) above.
4. Calculate the volume of the container.
Loose Unit...