NETTCP Soils and Aggregates 3

Question 1

The California Bearing Ratio (CBR) test measures:

Accepted Answer

Resistance of subgrade to penetration relative to a standard crushed stone

Answer

CBR compares the load required to penetrate a soil specimen to the load required to penetrate a standard high-quality crushed limestone.

Question 2

What is the purpose of the sand equivalent (SE) test for fine aggregate?

Accepted Answer

Measure the proportion of clay-like fines relative to sand-size particles

Answer

The sand equivalent test quantifies the relative amount of fine dust or clay-like material in fine aggregate using a flocculation procedure.

Question 3

When field moisture content is above optimum during compaction, the likely result is:

Accepted Answer

Pumping and rutting of the subgrade

Answer

Compacting soil wetter than optimum moisture results in a weak, unstable subgrade that can pump and rut under roller or traffic loads.

Question 4

A soil classified as A-7-6 under AASHTO is best described as:

Accepted Answer

Highly plastic clay, generally poor subgrade

Answer

A-7-6 soils are highly plastic clays with high volume change potential, considered the poorest subgrade materials under AASHTO classification.

Question 5

Which aggregate property is tested using the sodium sulfate soundness test?

Accepted Answer

Resistance to weathering and freeze-thaw degradation

Answer

The sodium sulfate soundness test simulates freeze-thaw action to evaluate aggregate durability against weathering deterioration.

(NETTCP) New England Transportation Technician Certification Program Practice Test