Practice Test Geeks(ATT) ACI Aggregate Testing Technician Practice Test
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Sieve Analysis & Gradation Flashcards

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  1. For coarse aggregate gradation testing, ASTM C136 requires that the sample be reduced to the proper test size using which method?

    Answer: Mechanical splitter or quartering per ASTM C702

    ASTM C702 covers methods for reducing field samples of aggregate to testing size, using a mechanical splitter or the quartering method to ensure representative subsamples.

  2. Which sieve size represents the boundary between fine and coarse aggregate per ASTM C33?

    Answer: No. 4 (4.75 mm)

    The No. 4 (4.75 mm) sieve is the dividing line: material retained on the No. 4 is classified as coarse aggregate, and material passing is classified as fine aggregate.

  3. A gradation curve that plots entirely near the upper limit of a specification band indicates the aggregate is:

    Answer: Too fine for the specification

    Upper gradation limits represent more material passing (finer gradation); an aggregate near the upper limit is finer than ideal and may require mix adjustments.

  4. When checking sieve adequacy after mechanical sieving, a technician individually hand-sieves each fraction for 1 minute. The result is adequate if:

    Answer: Less than 1% of the mass on that sieve passes during the 1-minute check

    ASTM C136 states sieving is complete when no more than 1% of the mass retained on that sieve passes during 1 minute of hand sieving.

  5. The maximum size of aggregate is defined as:

    Answer: The smallest sieve opening through which 100% of the aggregate passes

    Maximum size is the smallest sieve opening through which 100% of the aggregate must pass, making it one step smaller than the nominal maximum size.

  6. If a sieve analysis shows that 68% passes the No. 4 sieve for a blended aggregate, the percent retained on the No. 4 sieve is:

    Answer: 32%

    Percent retained = 100% − percent passing = 100% − 68% = 32%; this relationship is always true for any sieve.

  7. Aggregate gradation affects concrete mix design primarily by influencing:

    Answer: Water demand, workability, and the amount of cement paste required

    Gradation controls total surface area and void content of the aggregate skeleton, directly affecting how much water and paste are needed to coat particles and achieve workability.