ATT Fine Aggregate Quality Tests 2 — Questions and Answers
Question 1: According to ASTM C117, what does the wash method for material finer than the No. 200 sieve measure?
- Total clay and silt content washed through the sieve (Correct answer)
- Organic impurity level in fine aggregate
- Moisture content of the aggregate sample
- Fineness modulus of the washed sample
Correct answer: Total clay and silt content washed through the sieve
ASTM C117 determines the amount of material finer than 75 µm (No. 200 sieve) by washing, which removes clay, silt, and dust of fracture.
Question 2: When performing the organic impurities test (ASTM C40), a color darker than the standard indicates:
- The aggregate may be injurious and should be further tested (Correct answer)
- The aggregate is acceptable for all concrete uses
- The aggregate has excessive moisture content
- The aggregate fails the gradation requirement
Correct answer: The aggregate may be injurious and should be further tested
A color darker than the reference standard solution (Gardner Color Standard No. 11) suggests potentially harmful organic impurities requiring additional testing per ASTM C87.
Question 3: The fineness modulus of fine aggregate is calculated by summing the cumulative percentages retained on which sieves?
- No. 100, No. 50, No. 30, No. 16, No. 8, No. 4 (Correct answer)
- No. 200, No. 100, No. 50, No. 30, No. 16, No. 8
- No. 50, No. 30, No. 16, No. 8, No. 4, 3/8 in.
- No. 4, No. 8, No. 16, No. 30, No. 50, No. 100, No. 200
Correct answer: No. 100, No. 50, No. 30, No. 16, No. 8, No. 4
Fineness modulus uses cumulative percent retained on the No. 100, 50, 30, 16, 8, and 4 sieves, divided by 100.
Question 4: ASTM C128 determines which properties of fine aggregate?
- Specific gravity and absorption capacity (Correct answer)
- Gradation and fineness modulus
- Organic impurities content
- Clay lumps and friable particles
Correct answer: Specific gravity and absorption capacity
ASTM C128 covers the determination of bulk and apparent specific gravity and absorption capacity of fine aggregate.
Question 5: In ASTM C128, the saturated surface-dry (SSD) condition of fine aggregate is detected using the cone test when:
- The cone slumps slightly after the mold is lifted (Correct answer)
- The cone retains its shape perfectly after lifting
- The cone completely collapses immediately
- The cone shows surface water glistening
Correct answer: The cone slumps slightly after the mold is lifted
At SSD, the sand cone slumps slightly — a perfect cone indicates surface moisture present; complete collapse means the aggregate is too dry.
Question 6: The soundness test for fine aggregate (ASTM C88) uses which reagents to assess durability?
- Sodium sulfate or magnesium sulfate solution (Correct answer)
- Hydrochloric acid or sodium hydroxide
- Sodium chloride or potassium chloride
- Sulfuric acid or acetic acid
Correct answer: Sodium sulfate or magnesium sulfate solution
ASTM C88 subjects aggregate to repeated immersion in sodium sulfate or magnesium sulfate solutions to simulate weathering and freeze-thaw effects.
Question 7: ASTM C142 measures which deleterious substance in fine aggregate?
- Clay lumps and friable particles (Correct answer)
- Material finer than No. 200 sieve
- Organic impurities
- Lightweight pieces in aggregate
Correct answer: Clay lumps and friable particles
ASTM C142 determines clay lumps and friable particles by hand-crushing moist particles and sieving out the degraded material.
ATT Fine Aggregate Quality Tests 2
According to ASTM C117, what does the wash method for material finer than the No. 200 sieve measure?