Superpave Asphalt Binder PG Calculator

Q: What does a grade like PG 64-22 mean?

PG 64-22 indicates the asphalt binder satisfies high-temperature rutting criteria up to a 7-day average maximum pavement design temperature of 64°C, and resists low-temperature thermal cracking down to a minimum winter pavement surface temperature of -22°C.

Q: Why does polymer modification (SBS) decrease the phase angle delta?

Styrene-butadiene-styrene (SBS) block copolymers create a crosslinked elastomeric network within the maltene phase of the bitumen. This increases the elastic storage modulus (G') and drives phase angle δ below 75° (compared to 85°-88° for neat asphalt), giving the binder spring-like memory to bounce back from heavy wheel ruts.

Q: What is grade bumping in Superpave?

For heavy slow-moving freight corridors (toll plazas, intersections, bus lanes), the effective loading time is much longer. To prevent rutting, engineers "bump" the required high-temperature grade by one or two increments (e.g. specifying PG 76-22 instead of PG 64-22).

Asphalt rheology & materials engineering: Evaluate Superpave Performance Grading (PG) rheological metrics: DSR high-temperature rutting ($G^*/sindelta$), intermediate fatigue ($G^* cdot sindelta$), and BBR low-temperature stiffness ($S$).

DSR Rheological Test Data

Test Temperature T (°C): Standard 6°C PG grade increments

Aging State: Simulated aging history

Complex Shear Modulus |G*| (kPa): Dynamic Shear Rheometer modulus

Phase Angle δ (°): Elastic (0°) vs Viscous (90°) response

BBR Creep Stiffness S at 60s (MPa): Limit: ≤ 300 MPa

BBR m-Value at 60s: Creep relaxation slope (Limit: ≥ 0.300)

Superpave Specification Compliance

Rutting Parameter (G* / sin δ)

Fatigue Parameter (G* · sin δ)

Storage Modulus G' (Elastic)

G' = |G*| · cos δ

Loss Modulus G'' (Viscous)

G'' = |G*| · sin δ

Low-Temp Cracking Check

S ≤ 300 MPa & m ≥ 0.300

Polymer Modification Indicator

Phase angle δ < 75°

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Frequently Asked Questions

What does a grade like PG 64-22 mean?

PG 64-22 indicates the asphalt binder satisfies high-temperature rutting criteria up to a 7-day average maximum pavement design temperature of 64°C, and resists low-temperature thermal cracking down to a minimum winter pavement surface temperature of -22°C.

Why does polymer modification (SBS) decrease the phase angle delta?

Styrene-butadiene-styrene (SBS) block copolymers create a crosslinked elastomeric network within the maltene phase of the bitumen. This increases the elastic storage modulus (G') and drives phase angle δ below 75° (compared to 85°-88° for neat asphalt), giving the binder spring-like memory to bounce back from heavy wheel ruts.

What is grade bumping in Superpave?

For heavy slow-moving freight corridors (toll plazas, intersections, bus lanes), the effective loading time is much longer. To prevent rutting, engineers "bump" the required high-temperature grade by one or two increments (e.g. specifying PG 76-22 instead of PG 64-22).