Asphalt Flashcards
(19 cards)
What is Asphalt Cement?
Viscous liquid or semi-solid petroleum product (bitumen)
Asphalt Cement serves as the binder in asphalt mixtures.
Define Asphalt Concrete.
Mix of aggregate + asphalt binder
Asphalt Concrete is the primary material used in pavement construction.
What is Cutback Asphalt?
Asphalt + solvent (e.g., diesel, kerosene)
Cutback Asphalt is available in rapid, medium, and slow-curing types.
List the types of Emulsified Asphalt.
- Cationic (positive)
- Anionic (negative)
- Non-ionic
Emulsified Asphalt is created by mixing asphalt with water and a surfactant.
What is the thermoplastic property of asphalt?
Behavior changes with temperature
This means asphalt can become softer or harder depending on the heat.
Describe the viscoelastic behavior of asphalt.
- Short-term: Elastic (spring-like)
- Long-term: Viscous (flow)
This property affects how asphalt responds to loads over time.
What happens to asphalt at high temperatures?
Softens in heat
High temperatures reduce the viscosity of asphalt, making it more workable.
What is the impact of cold temperatures on asphalt?
Brittle in cold
Cold temperatures can cause asphalt to crack due to reduced flexibility.
What characterizes Dense-Graded mixtures?
Full range of aggregate sizes; high stability
Dense-Graded mixtures provide strong and durable pavements.
Define Open-Graded mixtures.
Gap in aggregate sizes; better drainage
Open-Graded mixtures are used to enhance water drainage in pavements.
What is Gap-Graded mixture?
Avoid certain sizes to control structure
This type of mixture is designed to optimize the performance of asphalt.
What causes Fatigue Cracking in pavements?
Due to repeated loading
Fatigue Cracking is a common issue in heavily trafficked areas.
What is Rutting?
Permanent deformation under wheel paths
Rutting occurs when asphalt fails to recover from the stresses of traffic.
What leads to Thermal Cracking?
From shrinkage at low temperatures
As the pavement temperature drops, the asphalt concrete contracts, and if the restrained contraction creates tensile stresses that exceed the material’s strength, cracks form
Thermal Cracking can significantly affect pavement integrity during cold weather.
What is Stripping in asphalt pavements?
Loss of bond due to water
Stripping is the breakdown of the adhesive bond between the aggregate and the asphalt cement. This process occurs when water gets in between the aggregate surface and replaces the asphalt coating.
Stripping results in reduced strength and durability of the pavement.
What causes Potholes?
Due to freeze-thaw cycles
Potholes in asphalt and concrete pavement are primarily caused by a combination of water, traffic, and the age and condition of the pavement. Water seeps into cracks in the pavement and then, especially during freeze-thaw cycles, can expand and weaken the underlying structure. Traffic then further breaks down the weakened surface, leading to potholes
Potholes are a common issue that occurs when water infiltrates cracks and freezes.
What is the importance of Surface Dryness for adhesion?
Essential for bonding
A dry surface ensures that the asphalt binder can effectively bond with the aggregate.
How does Aggregate Surface Energy affect bonding?
Higher = better bonding
Aggregate surface energy refers to the energy associated with the surfaces of individual aggregate particles, or the energy required to create or break bonds at the surface of an aggregate.
Aggregates with higher surface energy provide stronger adhesion with asphalt.
What is Water Sensitivity in asphalt pavements?
Water can displace binder
This property can lead to reduced performance and durability of asphalt mixtures.
