NETTCP Sampling Methods 5

Question 1

Which AASHTO standard practice specifically addresses sampling of freshly mixed Portland cement concrete?

Accepted Answer

AASHTO T 141

Answer

AASHTO T 141 is the standard method for sampling freshly mixed concrete.

Question 2

When sampling HMA from windrows (material deposited ahead of the paver), what precaution is most critical?

Accepted Answer

Sample only from the center of the windrow, avoiding the edges where heat loss is greatest

Answer

Windrow edges lose heat faster and may include pavement contact contamination, so sampling the center provides a more representative and thermally consistent specimen.

Question 3

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?

Accepted Answer

Station 187 feet and 7 feet from the reference edge

Answer

In the random-number method, the first number typically gives the longitudinal station and the second gives the transverse offset from a reference edge.

Question 4

When a field sample of aggregates is collected, it must be transported to the laboratory in a container that:

Accepted Answer

Is clean, rigid, and prevents moisture loss or gain

Answer

Sample containers must be clean and rigid to prevent contamination, and sealed to preserve the in-situ moisture content if required.

Question 5

In acceptance testing, what statistical parameter is most commonly used alongside the mean of test results to quantify variability within a lot?

Accepted Answer

Standard deviation

Answer

Standard deviation quantifies the spread of individual test results around the mean, which is used in PWL (percent within limits) calculations for lot acceptance.

(NETTCP) New England Transportation Technician Certification Program Practice Test

(NETTCP) New England Transportation Technician Certification Program Practice Test

NETTCP Sampling Methods 5