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INSTRUCTOR: 
David K. Hein, P.Eng.

Purpose and Background

The need and use of bases and sub-bases for pavements has been well known for thousands of years. The Romans built over 53,000 miles of roads to move troops and supplies beginning in about 500 BC. The Romans recognized the benefits of “protecting” the natural earth subgrade from the impact of the repeated loading of their carts and chariots. Roads such as the Appian Way were constructed of multiple layers of stones ( sub-base, base, and surface) and were sloped to drain water away from the road.

The types and sizes of materials used for early pavements bases varied from well compacted clay to sands and gravels to various sizes of “rocks” placed in layers of various thicknesses. With the use of “bound” materials such as asphalt concrete and concrete for the road surfaces, most pavements were constructed with larger size aggregates sub-bases with one or more layers of “base” consisting of smaller aggregates on top of the sub-base to provide a platform for the pavement surface.

Pivotal work on pavement design by the U.S. Army Corps of Engineers and others in the 1940s led to a much better understanding of the importance of using bases and sub-bases, their uniformity, and degree of compaction. A key finding was the importance of quality bases and sub-bases for pavements. With an increase in traffic loads, volume, and speed for both aircraft and vehicular traffic distresses (e.g. faulting, roughness, and corner breaks for concrete pavements), alligator cracking, distortions and rutting for asphalt pavement became much more prevalent. European pavement design methods tend to focus strongly on the importance of sub-grade support and the protection of the subgrade through the use of high quality, uniform bases and sub-bases which are surfaced with only the minimum amount of bound material required to support traffic loading. This permits a sustainable pavement strategy where timely preventive maintenance and rehabilitation treatments can be used to maximize pavement life. In North America, we typically permit pavements to reach a much lower level of service before more significant rehabilitation treatments are required to return the pavement to an appropriate level of service.

This webinar outlines the types of bases and sub-bases that can be used for flexible and rigid pavements, discusses key material characteristics, construction procedures, and provides quality assurance/control processes key to ensuring long-term durability of the pavement.

Primary Discussion Topics

• Basics of rigid and flexible pavement base/ sub-base design
• Materials for bases/sub-bases
• Construction of bases/sub-bases
• Cost considerations
• Quality assurance/control
• Key features to ensure pavement longevity

Benefits and Learning Outcomes

Upon completion of this course, you will be able to:

• Understand the types of bases and sub-bases used for pavements
• Recognize key design base/sub-base features needed to build long-life flexible pavements
• Understand the importance of pavement layer materials/properties
• Learn what to look for during construction to ensure high quality
• Understand the positive and negative impacts of alternative pavement materials
• Describe the types and functions of bases/sub-bases for pavements
• Determine the importance of key design features
• Recognize important base/sub-base material requirements
• Recognize construction deficiencies and their impact and pavement performance
• Optimize pavement investment

Assessment of Learning Outcomes

Students' achievement of the learning outcomes will be assessed via a short post-assessment (true-false, multiple choice and fill in the blank questions).

Who Should Attend?

• Civil engineers responsible for the design, construction, maintenance and rehabilitation of pavements
• Agencies and other owners of highway, municipal and private sector pavement infrastructure
• Pavement material suppliers and contractors
• Operations personnel responsible for the maintenance and rehabilitation of pavements

Outline

• Overview of rigid and flexible pavement design and purpose
• Basics for base/sub-base construction to ensure performance
• Understand the cost benefits of selecting a particular base/sub-base
• Target quality control/assurance processes for success
• Recognize key design and construction features that impact performance

How to Earn your CEUs/PDHs

This course is worth .1 CEU’s /1 PDHs. To receive your certificate of completion, you will need to complete a short on-line post-test and receive a passing score of 70% or higher within 365 days of the course.

How do I convert CEUs to PDHs?

1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]