NETTCP Quality Control 3

Question 1

According to AASHTO standards, what is the minimum number of compressive strength cylinders that should be cast per concrete sample?

Accepted Answer

Two cylinders per sample

Answer

AASHTO T 23 / ASTM C 31 typically requires at least two cylinders per test age so results can be averaged and outliers identified.

Question 2

What does a Proctor compaction test establish for a given soil?

Accepted Answer

Optimum moisture content and maximum dry density

Answer

The Proctor test (AASHTO T 99 or T 180) determines the optimum moisture content at which a soil achieves its maximum dry density under a specific compactive effort.

Question 3

Which property of an asphalt binder is measured by the Dynamic Shear Rheometer (DSR)?

Accepted Answer

Viscoelastic properties including complex shear modulus and phase angle

Answer

The DSR measures G* (complex shear modulus) and δ (phase angle), which describe an asphalt binder's stiffness and elastic behavior at service temperatures.

Question 4

When sampling freshly mixed concrete from a truck mixer, ASTM C 172 requires that the sample be obtained within what time period after sampling begins?

Accepted Answer

Within 5 minutes

Answer

ASTM C 172 requires that the composite sample be obtained within 5 minutes to ensure it represents a single batch without significant hydration changes.

Question 5

A QC technician receives failing density results from a nuclear gauge on a freshly compacted aggregate base course. What should be done before requesting a retest?

Accepted Answer

Verify gauge calibration with a standard count and check moisture assumption

Answer

Before acting on failing results, the technician should confirm the gauge is properly calibrated and that the moisture correction is accurate to rule out equipment error.

(NETTCP) New England Transportation Technician Certification Program Practice Test

(NETTCP) New England Transportation Technician Certification Program Practice Test

NETTCP Quality Control 3