ATT Flat, Elongated Particles & Sand Equivalent Flashcards
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Which ASTM standard governs the sand equivalent value test for coarse-grained soils and fine aggregates?
Answer: ASTM D2419
ASTM D2419 is the standard test method for sand equivalent value of soils and fine aggregate.
In the sand equivalent test (ASTM D2419), the purpose of the flocculating solution (calcium chloride) is to:
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.
How is the sand equivalent (SE) value calculated in ASTM D2419?
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.
A higher sand equivalent value in ASTM D2419 indicates:
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.
In the sand equivalent test, the sample and flocculating solution are shaken and then allowed to stand for how long before taking readings?
Answer: 20 minutes
After shaking, the ASTM D2419 test requires a 20-minute sedimentation period before measuring the sand and clay column heights.
What minimum sand equivalent value does ASTM C33 typically require for fine aggregate used in concrete?
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.