CCIL Superpave Mix Design 3

Question 1

What does the Superpave parameter 'Dust Proportion' (DP) measure and what is its typical acceptable range?

Accepted Answer

The ratio of P0.075 to effective binder content; typically 0.6–1.2

Answer

Dust Proportion equals the percentage passing the 0.075 mm sieve divided by the effective binder content, and values between 0.6 and 1.2 indicate a balanced mix.

Question 2

During Superpave mix design, what condition must be met at N_initial gyrations?

Accepted Answer

The relative density must not exceed 89% of theoretical maximum density (Gmm)

Answer

At N_initial, the mix density must not exceed 89% Gmm; exceeding this limit suggests the mix may over-compact under traffic and become unstable.

Question 3

How is the Theoretical Maximum Density (Gmm) of an asphalt mixture determined?

Accepted Answer

By the Rice test (ASTM D2041), dissolving air voids in a vacuum-sealed container with water

Answer

Gmm is determined by the Rice method (ASTM D2041/AASHTO T209), which removes air voids under vacuum and measures the void-free density of the loose mixture.

Question 4

Which Superpave aggregate test evaluates the angularity of fine aggregates?

Accepted Answer

Uncompacted Void Content of Fine Aggregate (AASHTO T304)

Answer

The Uncompacted Void Content test (AASHTO T304) measures the void space in loosely placed fine aggregate, with higher values indicating more angular particles that provide better shear resistance.

Question 5

What is the effect of increasing the nominal maximum aggregate size (NMAS) in a Superpave mix?

Accepted Answer

VMA decreases, allowing for less binder while maintaining durability

Answer

Larger NMAS mixes generally produce lower VMA because coarser gradations pack more efficiently, which can reduce binder content requirements.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Superpave Mix Design 3