This section contains some of the more frequently asked pavement questions. Each question is linked either to a place in this document that provides the answer or to a public web resource that answers the question posed.
General
- How do I find a Washington Asphalt Pavement Association member paving contractor in my area?
- Where can I find more information like this on hot mix asphalt (HMA) pavements?
- What is hot mix asphalt (HMA)?
- Is there a difference between tar and asphalt?
- What is a pavement’s purpose?
- How much do we use roads in the U.S.?
Pavement Types
- What types of pavement are there?
- Are there different kinds of hot mix asphalt?
- What are the benefits of paving with asphalt?
- What is Superpave?
- What is Stone Matrix Asphalt (SMA)?
- What is asphalt treated base (ATB)?
- What is RAP and how is it used?
- What types of standard HMA mixes are used in Washington State (e.g., Class A, Class G, etc.)?
- What is a Modified Class B mix?
Materials
- What is the difference between maximum aggregate size and nominal maximum aggregate size?
- What is the PG asphalt binder grading system?
- What is an asphalt binder modifier?
Design Factors
- What is the difference between a CBR, R-Value and resilient modulus and how do I correlate them to one another?
- What is an equivalent single axle load (ESAL)?
- What is frost heave and should I worry about it?
Mix Design
- What is a job mix formula (JMF)?
- What are the differences between the Hveem, Marshall and Superpave methods?
Structural Design – Design Catalog
- How thick should I make my pavement?
- What are the basic structural elements in a pavement?
- What is a Perpetual Pavement?
Construction
- How should I prepare the surface over which I plan to place a new pavement or overlay?
- What is “Rice density”?
- Why are density measurements given as a percentage?
- Why are density and compaction so important?
Pavement Evaluation
- What is IRI?
- How are pavements evaluated?
- What is a life cycle cost analysis and are there any tools to help me perform one on a proposed pavement?
Maintenance & Rehabilitation
- What is a bituminous surface treatment, or chip seal?
- Are all overlays used to increase the structural capacity of a pavement?
General Guidance
