At high service temperatures, asphalt binders must retain elasticity to prevent permanent deformation; at low temperatures, the binder must flow to relax stresses.

• A. False
• B. Cannot be determined
• C. True
• D. Only applicable to binders with PG 52

Answer: (C)

The main idea is that asphalt binder behaves as a viscoelastic material, changing how it responds to loads with temperature. At high service temperatures, you want the binder to resist permanent deformation, which means it should retain elasticity so it can snap back after being deformed by traffic rather than flow and create rutting. At low temperatures, some flow is desirable because the viscous part of the binder helps relax stresses from contraction and loading, reducing the chance of brittle cracking. So the binder’s elasticity at high temperatures plus its ability to flow (relax stresses) at low temperatures is exactly what helps the pavement stay durable across the temperature range. This behavior isn’t limited to a specific PG grade; it’s a general characteristic of how asphalt binders are expected to perform.