ATT ATT Deleterious Materials & Clay Content 2 — Questions and Answers
Question 1: Which ASTM standard is used to determine lightweight pieces in aggregate (such as coal and lignite)?
- ASTM C123 (Correct answer)
- ASTM C142
- ASTM C40
- ASTM C127
Correct 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.
Question 2: In ASTM C123, lightweight particles are separated from aggregate by:
- Heating to 100°C and measuring mass loss
- Immersion in a heavy liquid of specified density (Correct answer)
- Magnetic separation
- Acid dissolution
Correct 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.
Question 3: What is the maximum allowable lightweight pieces (coal and lignite) in fine aggregate per ASTM C33 for concrete subject to surface wear?
- 0.5% (Correct answer)
- 1.0%
- 1.5%
- 2.0%
Correct 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.
Question 4: Chert with a bulk specific gravity less than 2.40 is considered a deleterious substance in coarse aggregate because:
- It increases workability too much
- It has poor freeze-thaw durability and causes pop-outs (Correct answer)
- It reduces water demand
- It accelerates cement hydration
Correct 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.
Question 5: When testing for lightweight pieces per ASTM C123, the test result is expressed as:
- Number of particles per kilogram
- Percentage by mass of lightweight pieces (Correct answer)
- Percentage by volume
- Parts per million
Correct answer: Percentage by mass of lightweight pieces
ASTM C123 results are reported as the percentage by mass of lightweight pieces in the aggregate sample.
Question 6: Which of the following is NOT classified as a deleterious substance in aggregates per ASTM C33?
- Clay lumps
- Coal and lignite
- Chert of low specific gravity
- Well-graded crushed granite (Correct answer)
Correct answer: Well-graded crushed granite
Well-graded crushed granite is a sound, durable aggregate material and is not classified as a deleterious substance.
ATT ATT Deleterious Materials & Clay Content 2
Which ASTM standard is used to determine lightweight pieces in aggregate (such as coal and lignite)?