CCIL Superpave Mix Design 2

Question 1

In Superpave mix design, what does the term 'N_design' refer to?

Accepted Answer

The number of gyrations used to compact specimens to the design air void level

Answer

N_design is the number of gyrator compaction cycles at which the mix must achieve 4% air voids, representing the expected traffic loading.

Question 2

Which Superpave aggregate property measures resistance to polishing under traffic?

Accepted Answer

Flat and Elongated particle content

Answer

The Los Angeles Abrasion (LAA) test measures aggregate resistance to degradation, but polishing resistance is assessed via the British Pendulum or other polish tests; however, in Superpave, CAA and uncompacted void content address angularity, not polishing — polishing resistance is evaluated through aggregate source approval.

Question 3

What is the primary purpose of the Superpave gyratory compactor (SGC)?

Accepted Answer

To simulate field compaction by applying a kneading action with a fixed angle and pressure

Answer

The SGC simulates field compaction by rotating specimens at a 1.25° angle under 600 kPa pressure, replicating the kneading action of rubber-tired rollers.

Question 4

In Superpave volumetric design, VMA stands for:

Accepted Answer

Voids in the Mineral Aggregate

Answer

VMA (Voids in the Mineral Aggregate) is the intergranular void space in the compacted aggregate skeleton, including air voids and effective binder content.

Question 5

A Superpave mix design shows VFA = 58% at the design air void content. What does this indicate?

Accepted Answer

The binder fills only 58% of the VMA, which may be too low for adequate durability

Answer

VFA below 65% is generally below the minimum threshold, indicating insufficient binder to coat aggregates adequately, which can reduce durability and fatigue life.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Superpave Mix Design 2