Aggregate Sampling & Reduction Flashcards
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According to ASTM D75, what is the minimum number of increments required to constitute a field sample of aggregate from a conveyor belt?
Answer: 3 increments taken at random intervals
ASTM D75 requires a minimum of 3 increments taken at random intervals to form a representative field sample from a conveyor belt.
When sampling aggregates from a stockpile, where should samples generally NOT be taken from?
Answer: The outer surface or slope of the stockpile
Segregation occurs along the outer slopes of stockpiles, making surface samples unrepresentative of the bulk material.
The purpose of a sample splitter (riffle splitter) is to:
Answer: Reduce a large sample to a smaller representative portion
A riffle splitter divides a sample into two equal halves, allowing repeated halving to reach a target sample mass while maintaining representativeness.
Under ASTM C702, which method of sample reduction is acceptable for both fine and coarse aggregate?
Answer: Both the mechanical splitter and quartering method
ASTM C702 permits both mechanical splitting and the quartering method for reducing aggregate samples of fine or coarse aggregate.
When using the quartering method per ASTM C702, after forming the flat circular pile and dividing into four quarters, which portions are kept?
Answer: Two diagonally opposite quarters are discarded and the other two are combined
In quartering, two diagonally opposite quarters are kept and recombined; the other two opposite quarters are discarded, ensuring a representative half-sample.
What is the primary reason aggregate samples should be transported to the laboratory in sealed, airtight containers or bags?
Answer: To prevent loss of fines and moisture change
Sealing samples prevents loss of fine material and limits evaporation or absorption of moisture, both of which affect test results.
In ASTM D75, what does the term 'lot' refer to when sampling aggregates from a production unit?
Answer: A defined quantity of material from which a sample is obtained for quality acceptance
A 'lot' is a defined quantity of material selected for sampling and evaluation to determine whether it meets specification requirements.