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
Which AASHTO standard practice specifically addresses sampling of freshly mixed Portland cement concrete?
Answer: AASHTO T 141
AASHTO T 141 is the standard method for sampling freshly mixed concrete.
When sampling HMA from windrows (material deposited ahead of the paver), what precaution is most critical?
Answer: Sample only from the center of the windrow, avoiding the edges where heat loss is greatest
Windrow edges lose heat faster and may include pavement contact contamination, so sampling the center provides a more representative and thermally consistent specimen.
A technician is directed to obtain a 'random location' for a density test using the random-number method. The test section is 500 feet long and 12 feet wide. If the random numbers generated are 187 and 7, what do these represent?
Answer: Station 187 feet and 7 feet from the reference edge
In the random-number method, the first number typically gives the longitudinal station and the second gives the transverse offset from a reference edge.
When a field sample of aggregates is collected, it must be transported to the laboratory in a container that:
Answer: Is clean, rigid, and prevents moisture loss or gain
Sample containers must be clean and rigid to prevent contamination, and sealed to preserve the in-situ moisture content if required.
In acceptance testing, what statistical parameter is most commonly used alongside the mean of test results to quantify variability within a lot?
Answer: Standard deviation
Standard deviation quantifies the spread of individual test results around the mean, which is used in PWL (percent within limits) calculations for lot acceptance.
For sampling soils from a borrow area, which sampling device is best suited to obtain minimally disturbed samples from cohesive soils at depth?
Answer: Thin-walled Shelby tube sampler
The thin-walled Shelby tube is designed to obtain minimally disturbed cohesive soil samples by pushing (not driving) the tube into the formation.
A project specification requires that sampling locations be documented with GPS coordinates and station references. This documentation requirement primarily serves to:
Answer: Enable accurate retesting at the exact same location if results are disputed
Accurate location documentation allows the same spot to be retested for verification, ensuring the dispute resolution sample reflects the original test conditions.