ATT ATT Flat, Elongated Particles & Sand Equivalent 2 — Questions and Answers
Question 1: Which ASTM standard governs the sand equivalent value test for coarse-grained soils and fine aggregates?
- ASTM D2419 (Correct answer)
- ASTM C136
- ASTM C40
- ASTM D4791
Correct answer: ASTM D2419
ASTM D2419 is the standard test method for sand equivalent value of soils and fine aggregate.
Question 2: In the sand equivalent test (ASTM D2419), the purpose of the flocculating solution (calcium chloride) is to:
- Dissolve silica particles
- Cause clay and fine dust to flocculate and settle into a distinct layer (Correct answer)
- Increase the specific gravity of water
- Prevent oxidation of iron minerals
Correct answer: Cause clay and fine dust to flocculate and settle into a distinct layer
The calcium chloride flocculating solution causes clay particles and fine dust to coagulate and settle, forming a clear boundary between the sand and clay layers.
Question 3: How is the sand equivalent (SE) value calculated in ASTM D2419?
- SE = (Clay reading / Sand reading) × 100
- SE = (Sand reading / Clay reading) × 100 (Correct answer)
- SE = (Sand reading - Clay reading) × 100
- SE = (Clay reading - Sand reading) / 100
Correct answer: SE = (Sand reading / Clay reading) × 100
Sand equivalent is calculated as (sand reading ÷ clay reading) × 100, where a higher value indicates less clay or fine dust contamination.
Question 4: A higher sand equivalent value in ASTM D2419 indicates:
- More clay and plastic fines present
- Cleaner aggregate with less clay contamination (Correct answer)
- Higher moisture content
- More organic material
Correct answer: Cleaner aggregate with less clay contamination
A higher sand equivalent value means a greater proportion of clean sand relative to clay fines, indicating better aggregate quality.
Question 5: In the sand equivalent test, the sample and flocculating solution are shaken and then allowed to stand for how long before taking readings?
- 5 minutes
- 10 minutes
- 20 minutes (Correct answer)
- 30 minutes
Correct answer: 20 minutes
After shaking, the ASTM D2419 test requires a 20-minute sedimentation period before measuring the sand and clay column heights.
Question 6: What minimum sand equivalent value does ASTM C33 typically require for fine aggregate used in concrete?
- 25
- 50 (Correct answer)
- 75
- 80
Correct answer: 50
ASTM C33 does not specify a sand equivalent limit directly, but common specifications require a minimum SE of 75–80; however, a value of 75 is the widely accepted minimum for concrete sand.
ATT ATT Flat, Elongated Particles & Sand Equivalent 2
Which ASTM standard governs the sand equivalent value test for coarse-grained soils and fine aggregates?