PIC Aggregate & Binder Specifications 3

Question 1

Which test method determines the specific gravity of fine aggregate for use in HMA volumetric calculations?

Accepted Answer

AASHTO T 84

Answer

AASHTO T 84 determines the bulk specific gravity and absorption of fine aggregate (passing the 4.75mm sieve) used in volumetric mix design.

Question 2

The Dynamic Shear Rheometer (DSR) measures asphalt binder properties related to:

Accepted Answer

Rutting and fatigue cracking resistance

Answer

The DSR measures the complex shear modulus (G*) and phase angle (δ) of asphalt binder, which predict rutting resistance at high temperatures and fatigue cracking at intermediate temperatures.

Question 3

When aggregate flakiness or elongation exceeds specification limits, the most likely pavement distress is:

Accepted Answer

Particle breakdown and reduced stability

Answer

Flat and elongated aggregate particles are prone to breaking under compaction and traffic loads, reducing mix stability and long-term performance.

Question 4

The 'dust-to-binder ratio' (P0.075/Pbe) in Superpave mix design should typically fall between:

Accepted Answer

0.6 and 1.2

Answer

Superpave specifies a dust-to-binder ratio between 0.6 and 1.2 to ensure proper filler-binder interaction without excess stiffening or weakening of the mixture.

Question 5

Which test evaluates the stripping potential of HMA by measuring retained strength after moisture conditioning?

Accepted Answer

AASHTO T 283 (Lottman test)

Answer

AASHTO T 283 (commonly called the modified Lottman test) measures tensile strength ratio (TSR) by comparing conditioned to unconditioned specimens to evaluate moisture susceptibility.

(PIC) Paving Inspector Certification Practice Test

(PIC) Paving Inspector Certification Practice Test

PIC Aggregate & Binder Specifications 3