Technical
De-Bonding of HMA Pavements/Layer Bonding
Major Themes From Past Tack Coat Studies This section attempts to identify some of the emerging themes associated with tack coats based on a qualitative meta-analysis of past research. Ideas that are corroborated amongst multiple studies are briefly discussed under individual headings while ideas emerging from single studies that have yet to be corroborated by … Read more
HVS
HVS stands for Heavy Vehicle Simulator. It’s a large piece of equipment that allows for repeated passage of a truck or aircraft wheel over a pavement, simulating the action of many of such wheels from heavy vehicles. It is used in research to test pavement structures and roadway elements and their response to traffic. For … Read more
HVSIA
HVSIA definition and history Although Accelerated Pavement Testing (APT) is generally recognized as one of the most effective methods of evaluating improvements in pavement design and performance, it is expensive relative to other, typical pavement research activities. As a result, collaboration between APT programs, as well as other research efforts, is often discussed as a … Read more
Geosynthetics
Geosynthetics in HMA Applications The primary purpose of incorporating geosynthetics in the pavement design process is to reduce reflective cracking in HMA overlays and to resist moisture intrusion into the underlying pavement structure. Geosynthetics can be part of an overall rehabilitation strategy that will as a minimum include the placement of a new wearing/surface course … Read more
Life Cycle Assessment of Portland Cement Concrete Interstate Highway Rehabilitation and Replacement
by Craig D. Weiland A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, University of Washington, 2008 Abstract A Best Practices Guide to Concrete Highway Rehabilitation in Washington State, by Craig Weiland Life Cycle Assessment (LCA) is a tool that can be used to identify … Read more
Life Cycle Assessment of HMA and RAP
General I am interested in creating a comparative life cycle analysis of recycled vs. standard hot mix asphalt or HMA. In Washington State, up to 20% recycled HMA, called recycled asphalt pavement or RAP, is allowed in large-scale road construction such as state highways and interstate roadways. Researchers are looking onto using up to 100% … Read more
General Guidance
This is an informational resource on hot mix asphalt (HMA). It contains a general overview of all HMA aspects. It is intended to assist those who work with HMA in any way including architects, engineers, contractors, students, and homeowners. Pavement Checklist Pavement Distress Top-Down Cracking References Suggested Reading Asphalt Institute. (2001[1]). HMA Construction. Manual … Read more
Spalling
Description Cracking, breaking or chipping of joint/crack edges. Usually occurs within about 0.6 m (2 ft.) of joint/crack edge. Problem Loose debris on the pavement, roughness, generally an indicator of advanced joint/crack deterioration Possible Causes Possible causes are (AASHTO, 1993[1]): Excessive stresses at the joint/crack caused by infiltration of incompressible materials and subsequent expansion (can also … Read more
Faulting
Description A difference in elevation across a joint or crack usually associated with undoweled JPCP. Usually the approach slab is higher than the leave slab due to pumping, the most common faulting mechanism. Faulting is noticeable when the average faulting in the pavement section reaches about 2.5 mm (0.1 inch). When the average faulting reaches 4 … Read more
Bleeding
Description A film of asphalt binder on the pavement surface. It usually creates a shiny, glass-like reflecting surface (as in the first photo) that can become quite sticky. Sometimes referred to as “flushing”. Problem Loss of skid resistance when wet Possible Causes Bleeding occurs when asphalt binder fills the aggregate voids during hot weather and then expands … Read more
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