Practice Test Geeks(NETTCP) New England Transportation Technician Certification Program Practice Test
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Lab Testing Procedures Flashcards

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  1. Which AASHTO test method covers the determination of specific gravity and absorption of coarse aggregate?

    Answer: AASHTO T 85

    AASHTO T 85 covers specific gravity (bulk, SSD, apparent) and absorption of coarse aggregate, while T 84 covers fine aggregate.

  2. During a field density test with a nuclear gauge in backscatter mode, the gamma source and detectors are both:

    Answer: Located at the gauge base on the surface

    In backscatter mode, both the source and detectors remain at the surface; the gauge measures density of only the top few inches of material.

  3. A bituminous concrete specimen has a theoretical maximum specific gravity (Gmm) of 2.520 and a bulk specific gravity (Gmb) of 2.394. What is the air void content?

    Answer: 5.0%

    Va = (1 − Gmb/Gmm) × 100 = (1 − 2.394/2.520) × 100 = 5.0%; typical Superpave design targets 4% air voids.

  4. When performing the unconfined compressive strength test on a soil specimen, the height-to-diameter ratio of the specimen should be:

    Answer: 2:1 to 2.5:1

    ASTM D 2166 requires a height-to-diameter ratio between 2:1 and 2.5:1 to ensure proper failure plane development without end-restraint effects.

  5. The purpose of performing a soundness test on aggregates (AASHTO T 104) using sodium sulfate or magnesium sulfate is to evaluate:

    Answer: Resistance to weathering and freeze-thaw deterioration

    The soundness test simulates freeze-thaw action; salt crystallization in aggregate pores mimics ice expansion and reveals susceptibility to weathering.

  6. For HMA mixture design, the maximum theoretical specific gravity (Gmm) is determined per AASHTO T 209 by:

    Answer: Weighing a loose uncompacted asphalt mixture in air and submerged in water

    T 209 (Rice method) determines Gmm by measuring the mass of loose mix in air and the volume of mix plus water in a vacuum flask after removing air voids.

  7. According to AASHTO M 231, balances used in transportation materials testing must be verified and calibrated at a minimum of:

    Answer: Annually, or whenever moved or repaired

    AASHTO M 231 requires balance verification at least annually and after any event that could affect accuracy, such as relocation, repair, or overloading.