Practice Test Geeks(ATT) ACI Aggregate Testing Technician Practice Test
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Unit Weight & Voids Testing Flashcards

7 cards from real ATT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Unit Weight & Voids Testing flashcards as text

  1. When performing the unit weight test on coarse aggregate, how many layers are used when rodding a 1/2-cubic-foot measure?

    Answer: 3 layers

    ASTM C29 requires three equal layers when rodding aggregate in a 1/2-cubic-foot measure.

  2. What is the purpose of striking off the surface of the measure after filling in the unit weight test?

    Answer: To create a flat surface flush with the top of the measure

    Striking off levels the surface flush with the rim so the volume of aggregate equals exactly the volume of the measure.

  3. In ASTM C29, what tool is used to strike off the surface of the measure after the final layer of aggregate is added?

    Answer: A straightedge or tamping rod

    A straightedge or the tamping rod is used to strike off aggregate flush with the top of the measure.

  4. If the unit weight of a fine aggregate is 100 pcf and the specific gravity is 2.65, what is the approximate void content?

    Answer: About 39%

    Void content = (1 - UW / (SG × 62.4)) × 100 = (1 - 100/165.36) × 100 ≈ 39.5%.

  5. Which aggregate characteristic does a high void content typically indicate?

    Answer: Poorly graded or rounded particles with large interparticle spaces

    High void content usually indicates poorly graded or uniform-sized aggregate, or particles with shapes that do not pack efficiently.

  6. What must be done to the calibration mass used to determine the volume of the unit weight measure?

    Answer: It must be traceable to a standard and verified at appropriate intervals

    Calibration masses must be traceable to national standards and verified periodically to ensure accuracy of the measure volume calculation.

  7. When using the shoveling procedure in ASTM C29, aggregate is dropped from a height of approximately how many inches above the measure?

    Answer: 2 inches

    ASTM C29 specifies that aggregate be dropped from a height of approximately 2 inches (50 mm) above the top of the measure when using the shoveling method.