NETTCP Lab Testing Procedures 4

Question 1

A nuclear density gauge used for field compaction testing must be licensed under which U.S. federal agency because it contains radioactive material?

Accepted Answer

NRC (Nuclear Regulatory Commission)

Answer

Nuclear density gauges contain radioactive sources (Cesium-137 and Americium-241/Beryllium) and are regulated by the NRC or agreement states.

Question 2

In the Superpave gyratory compactor (SGC), what parameter is adjusted to simulate field compaction effort at different design levels?

Accepted Answer

Number of gyrations (Ndesign)

Answer

Ndesign is the number of gyrations used to compact asphalt specimens and is selected based on design traffic level (ESALs).

Question 3

Per AASHTO T 166, the bulk specific gravity of a compacted asphalt mixture specimen is determined using:

Accepted Answer

Saturated surface dry (SSD) weighing in air and submerged in water

Answer

Gmb is calculated from the dry mass, the SSD mass, and the submerged mass in water using Archimedes' principle.

Question 4

The California Bearing Ratio (CBR) test measures the strength of a subgrade soil relative to:

Accepted Answer

A standard crushed limestone base material

Answer

CBR expresses the penetration resistance of the test material as a percentage of the resistance of a standard well-graded crushed limestone.

Question 5

When splitting a bulk aggregate sample using a riffle splitter (sample splitter), the correct technique is to:

Accepted Answer

Feed material uniformly across all chutes at a controlled rate

Answer

Material must be fed uniformly across the full width of the splitter to ensure each half is a representative portion of the original sample.

(NETTCP) New England Transportation Technician Certification Program Practice Test