ATT ATT Deleterious Materials & Clay Content 1 — Questions and Answers
Question 1: Which ASTM standard covers the test method for clay lumps and friable particles in aggregates?
- ASTM C117
- ASTM C142 (Correct answer)
- ASTM C131
- ASTM C136
Correct answer: ASTM C142
ASTM C142 is the standard test method for clay lumps and friable particles in aggregates.
Question 2: In the clay lumps and friable particles test (ASTM C142), the sample is soaked in water for a period of:
- 1 to 4 hours
- 24 ± 4 hours (Correct answer)
- 48 hours minimum
- 12 ± 1 hours
Correct answer: 24 ± 4 hours
ASTM C142 requires soaking the sample in water for 24 ± 4 hours before attempting to break particles with the fingers.
Question 3: After soaking in ASTM C142, how are clay lumps and friable particles identified?
- By color change
- By attempting to crumble them between thumb and forefinger (Correct answer)
- By measuring density change
- By sieve washing only
Correct answer: By attempting to crumble them between thumb and forefinger
Particles that can be broken down by rubbing between the thumb and forefinger after soaking are classified as clay lumps or friable particles.
Question 4: According to ASTM C33, the maximum allowable clay lumps and friable particles in fine aggregate for concrete is:
- 1.0%
- 2.0%
- 3.0% (Correct answer)
- 5.0%
Correct answer: 3.0%
ASTM C33 limits clay lumps and friable particles in fine aggregate to a maximum of 3.0% by mass.
Question 5: What sieve size is used to separate the material retained for the clay lumps test in coarse aggregate per ASTM C142?
- No. 4 (4.75 mm) (Correct answer)
- No. 8 (2.36 mm)
- No. 16 (1.18 mm)
- 3/8 in. (9.5 mm)
Correct answer: No. 4 (4.75 mm)
For coarse aggregate, ASTM C142 testing uses material retained on the No. 4 (4.75 mm) sieve.
Question 6: Which deleterious substance in aggregate is most likely to cause unsightly staining and pop-outs in hardened concrete?
- Rounded quartz particles
- Coal and lignite particles (Correct answer)
- Well-graded limestone fines
- Crushed glass
Correct answer: Coal and lignite particles
Coal and lignite particles can expand, cause pop-outs, and produce dark staining on the surface of hardened concrete.
ATT ATT Deleterious Materials & Clay Content 1
Which ASTM standard covers the test method for clay lumps and friable particles in aggregates?