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Fresh Concrete Field Testing Flashcards

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

Read the first 6 Fresh Concrete Field Testing flashcards as text

  1. When performing a slump test per ASTM C143, the tamping rod should penetrate the preceding layer by approximately how much?

    Answer: Approximately 1 inch (25 mm) into the underlying layer

    ASTM C143 requires that the tamping rod penetrate approximately 1 inch (25 mm) into the underlying layer during filling to knit the layers together without excessively disturbing the lower portion.

  2. What does a 'shear slump' vs. a 'true slump' indicate when performing ASTM C143?

    Answer: A shear slump occurs when the concrete shears off to one side rather than subsiding evenly; it indicates an unrepresentative sample or harsh mix, and the test must be repeated

    In a shear slump, the upper portion slides off to one side instead of slumping uniformly; ASTM C143 requires that the test be repeated on a fresh sample because the result is not representative.

  3. At what precision must concrete temperature be recorded when performing field testing per ASTM C1064?

    Answer: To the nearest 1°F (0.5°C)

    ASTM C1064 requires that concrete temperature be reported to the nearest 1°F (0.5°C), using a thermometer with a resolution of at least 1°F and calibrated to ±1°F accuracy.

  4. When making concrete test cylinders per ASTM C31, how long must the molds remain undisturbed in the field after casting?

    Answer: A minimum of 24 hours and a maximum of 48 hours, stored at 60–80°F (16–27°C)

    ASTM C31 requires cylinders to remain in their molds in the field for a minimum of 24 hours and a maximum of 48 hours, protected from vibration and temperature extremes (60–80°F), before transport to the lab.

  5. Per ASTM C31, how many blows with a rubber mallet are required to close rod holes on each layer when making a 4×8-inch cylinder?

    Answer: 10–15 blows around the outside of the mold after each layer is rodded

    ASTM C31 requires 10–15 blows with a rubber mallet around the outside circumference of the mold after each layer is rodded, to close rod holes and eliminate surface voids regardless of cylinder size.

  6. What is the required composite sample volume when obtaining fresh concrete for a full set of field tests including two 4×8-inch cylinders per ASTM C172?

    Answer: At least 1.0 ft³ (28 L) to ensure sufficient material for all tests and cylinder fabrication

    A full set of tests including two 4×8-inch cylinders requires approximately 0.5–1.0 ft³; ASTM C172 recommends obtaining at least 1 ft³ when strength specimens will be made to allow for remixing and handling losses.