Practice Test Geeks(ATT) ACI Aggregate Testing Technician Practice Test
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Bulk Density, Voids & Organic Impurities 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 Bulk Density, Voids & Organic Impurities flashcards as text

  1. In the ASTM C29 rodding method for bulk density, how many times is the tamping rod inserted per layer?

    Answer: 25 times

    ASTM C29 requires the rod to be inserted 25 times per layer, distributing the strokes evenly over the surface.

  2. What concentration of NaOH solution is used in the ASTM C40 organic impurities test?

    Answer: 3% by weight

    ASTM C40 specifies a 3% sodium hydroxide (NaOH) solution by weight for detecting organic impurities in fine aggregate.

  3. What does a color darker than the reference standard in the ASTM C40 test indicate?

    Answer: The aggregate may contain injurious organic impurities

    A color darker than Organic Plate No. 3 indicates the fine aggregate may contain harmful organic impurities that could adversely affect concrete.

  4. How many approximately equal layers are used when filling the measure by the rodding method in ASTM C29?

    Answer: 3 layers

    ASTM C29 requires the measure to be filled in three approximately equal layers, each rodded 25 times.

  5. How long must the ASTM C40 test sample stand after adding NaOH before comparing colors?

    Answer: 24 hours

    ASTM C40 requires the sample and NaOH solution to stand for 24 hours before performing the color comparison.

  6. The rodding method in ASTM C29 is applicable for aggregates with a maximum particle size up to:

    Answer: 37.5 mm (1-1/2 in)

    The rodding method applies to aggregate with a maximum particle size not exceeding 37.5 mm (1-1/2 in); larger sizes require the jigging method.

  7. Which formula correctly calculates void content (%) per ASTM C29, where S = bulk specific gravity, W = density of water, and M = bulk density?

    Answer: (S × W − M) / (S × W) × 100

    Void content equals the theoretical solid volume minus the actual bulk density, divided by the theoretical solid volume, times 100.