ATT Deleterious Materials & Clay Content Flashcards
6 cards from real ATT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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Which ASTM standard is used to determine lightweight pieces in aggregate (such as coal and lignite)?
Answer: ASTM C123
ASTM C123 is the standard test method for lightweight pieces in aggregate, used to identify coal, lignite, and other low-density particles.
In ASTM C123, lightweight particles are separated from aggregate by:
Answer: Immersion in a heavy liquid of specified density
ASTM C123 uses a heavy liquid (such as zinc chloride solution) with a specific gravity between 1.95 and 2.0 to float out lightweight particles.
What is the maximum allowable lightweight pieces (coal and lignite) in fine aggregate per ASTM C33 for concrete subject to surface wear?
Answer: 0.5%
For fine aggregate in concrete subject to surface wear, ASTM C33 limits lightweight pieces (coal and lignite) to 0.5% by mass.
Chert with a bulk specific gravity less than 2.40 is considered a deleterious substance in coarse aggregate because:
Answer: It has poor freeze-thaw durability and causes pop-outs
Low-density chert absorbs water and deteriorates rapidly during freeze-thaw cycles, causing surface pop-outs in concrete.
When testing for lightweight pieces per ASTM C123, the test result is expressed as:
Answer: Percentage by mass of lightweight pieces
ASTM C123 results are reported as the percentage by mass of lightweight pieces in the aggregate sample.
Which of the following is NOT classified as a deleterious substance in aggregates per ASTM C33?
Answer: Well-graded crushed granite
Well-graded crushed granite is a sound, durable aggregate material and is not classified as a deleterious substance.