Sampling Methods Flashcards
7 cards from real NETTCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Sampling Methods flashcards as text
What is the purpose of a 'split sample' in transportation materials testing?
Answer: To create two identical samples for independent testing or referee analysis
Split samples allow independent verification by the agency and contractor, or serve as a referee sample if results are disputed.
When sampling liquid asphalt binder from a delivery tanker, from which location should the sample be drawn?
Answer: Through the sample valve at a mid-level or from multiple points
Sampling through a dedicated sample valve or at multiple tank levels ensures a representative sample of the homogeneous binder.
According to AASHTO practice, pavement cores taken for density determination should be extracted at what minimum distance from the edge of the pavement?
Answer: 12 inches
Cores must be taken at least 12 inches from the pavement edge to avoid edge effects that could produce unrepresentative density results.
A technician is sampling embankment fill for moisture-density control. The fill lifts are 8 inches thick. Where should in-place density tests be located vertically within the lift?
Answer: At mid-depth of the compacted lift
Density tests should be performed at mid-depth of the compacted lift to measure the representative density of that layer.
What does the term 'lot' refer to in pavement quality acceptance sampling plans?
Answer: A defined quantity of material for which one acceptance decision is made
A lot is a defined quantity (e.g., by tonnage or area) that is evaluated together to make a single accept/reject or pay-factor decision.
When using a nuclear density gauge on a compacted aggregate base, the gauge must be kept at what minimum distance from vertical obstructions like curbs or pavement edges?
Answer: 12 inches
Nuclear density gauges require at least 12 inches of clearance from vertical edges to prevent scatter readings from distorting results.
For Portland cement concrete pavement testing, cylinder specimens are fabricated from field samples. Which curing condition is required immediately after fabrication?
Answer: Initial moist curing at 60–80°F for the first 24–48 hours at the field site
Freshly cast concrete cylinders must be moist-cured at the field site within the specified temperature range to prevent early drying or freezing before transport to the lab.