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Strength Testing Technician Flashcards

7 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.

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  1. Per ASTM E4, how often must the testing machine used for compressive strength tests be verified for force-measurement accuracy?

    Answer: Every 12 months

    ASTM E4 requires testing machines to be verified at least every 12 months and whenever there is reason to question their accuracy.

  2. Unbonded neoprene pad caps used as an alternative to sulfur mortar for compressive strength testing must conform to which ASTM standard?

    Answer: ASTM C1231

    ASTM C1231 governs the use of unbonded neoprene pads in retaining rings as an alternative to sulfur mortar caps for testing concrete cylinders.

  3. Per ASTM C1231, which Shore A durometer hardness neoprene pad is specified for testing concrete with a design compressive strength up to 7,000 psi (50 MPa)?

    Answer: 50 durometer

    ASTM C1231 specifies 50 durometer neoprene pads for concrete with design strengths from 1,500 to 7,000 psi (10 to 50 MPa).

  4. Per ASTM C617, the maximum allowable thickness of a sulfur mortar cap on a test cylinder is:

    Answer: 3/16 inch (5 mm)

    ASTM C617 requires caps to be as thin as practicable and not exceed 3/16 inch (5 mm) in thickness.

  5. Which ASTM standard governs the flexural strength of concrete using a simple beam with third-point loading?

    Answer: ASTM C78

    ASTM C78 covers the determination of flexural strength (modulus of rupture) using a simple beam with third-point loading.

  6. A compressive testing machine must be accurate to within what percentage of the indicated load throughout the range being used, per ASTM E4?

    Answer: ± 1.0%

    ASTM E4 requires the force-indicating system to be accurate within ± 1% of the indicated load in the range being used.

  7. When sampling fresh concrete from a truck mixer per ASTM C172, a composite sample must be obtained from at least how many regularly spaced portions of the discharge?

    Answer: Two or more portions throughout the middle of discharge

    ASTM C172 requires composite samples to be taken from two or more regularly spaced portions throughout the middle 80% of the discharge.