CCIL Performance Graded (PG) Asphalt Binder Testing

Question 1

What does the high-temperature PG grade number (e.g., PG 64-XX) indicate about an asphalt binder?

Accepted Answer

The maximum pavement temperature at which the binder meets stiffness requirements to resist rutting

Answer

The high-temperature grade number represents the highest 7-day maximum pavement design temperature (°C) at which the binder meets the required G*/sinδ ≥ 1.0 kPa criterion as measured by the Dynamic Shear Rheometer (DSR). It defines the binder's ability to resist permanent deformation (rutting) at elevated service temperatures.

Question 2

The Dynamic Shear Rheometer (DSR) is used to measure which property of an asphalt binder?

Accepted Answer

Complex shear modulus (G*) and phase angle (δ)

Answer

The DSR measures the complex shear modulus G* (overall stiffness) and the phase angle δ (ratio of viscous to elastic response) of an asphalt binder. For unaged and RTFO-aged binders, the criterion is G*/sinδ ≥ 1.0 kPa to ensure sufficient rutting resistance; for PAV-aged binders, G*×sinδ ≤ 5,000 kPa ensures adequate fatigue resistance.

Question 3

What is the primary purpose of the Rolling Thin Film Oven (RTFO) test in PG binder evaluation?

Accepted Answer

To simulate short-term aging of the binder during hot mix plant production

Answer

The RTFO (AASHTO T 240 / ASTM D2872) simulates the aging that occurs to asphalt binder during the hot mix production and placement process (short-term aging). Binder films rotate in small bottles inside a heated oven at 163°C for 85 minutes, replicating the oxidative hardening experienced during mixing and compaction.

Question 4

In the Bending Beam Rheometer (BBR) test, which two parameters are measured to evaluate low-temperature cracking resistance?

Accepted Answer

Creep stiffness (S) and m-value

Answer

The BBR (AASHTO T 313) measures creep stiffness S(t) and the relaxation rate m-value of PAV-aged binder at a specified low temperature. The Superpave criteria require S ≤ 300 MPa (binder not too stiff) and m ≥ 0.300 (binder able to relax thermal stresses quickly enough) to resist low-temperature cracking.

Question 5

A PG 58-34 binder is specified for a project. What does the '-34' designation signify?

Accepted Answer

The minimum pavement temperature in °C at which the binder meets low-temperature cracking criteria

Answer

The low-temperature grade number (−34) represents the lowest pavement design temperature (°C) at which the binder meets the BBR criteria (S ≤ 300 MPa, m ≥ 0.300) after PAV aging, ensuring the binder remains sufficiently flexible and stress-relaxing to resist thermal cracking in cold climates.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Performance Graded (PG) Asphalt Binder Testing