NETTCP Sampling Methods 3

Question 1

What is the minimum number of grab samples typically combined to form a composite sample of Portland cement concrete during placement?

Accepted Answer

3

Answer

AASHTO R 60 specifies that a composite concrete sample is made from at least three grab samples taken at regular intervals during discharge.

Question 2

A field sample of aggregates taken from a stockpile must avoid the outer surface layer because:

Accepted Answer

Segregated or degraded material collects at the surface and edges

Answer

The outer layer of a stockpile accumulates segregated coarse particles and may contain contamination, making it unrepresentative.

Question 3

For HMA acceptance testing, which sampling method involves collecting material directly from the paver's hopper?

Accepted Answer

Hopper sampling

Answer

Hopper sampling involves collecting HMA directly from the paver's hopper before it is laid, capturing a sample representative of incoming material.

Question 4

When sampling soil from a test pit for density testing purposes, which layer is sampled first?

Accepted Answer

Deepest layer to avoid disturbance from upper layers

Answer

Sampling begins at the bottom of the excavation to prevent contamination from material falling from disturbed upper layers.

Question 5

A lot acceptance plan for pavement base course uses systematic sampling, taking one sample every 500 tons. If a lot is 3,200 tons, how many samples are collected?

Accepted Answer

7

Answer

3,200 tons ÷ 500 tons/sample = 6.4, which rounds up to 7 samples to cover the entire lot.

(NETTCP) New England Transportation Technician Certification Program Practice Test

(NETTCP) New England Transportation Technician Certification Program Practice Test

NETTCP Sampling Methods 3