Using Ground Penetrating Radar (GPR) to Evaluate Air Voids Content in Hot Mix Asphalt
Abstract
"Air voids content is one of the most important characteristics of Hot Mix Asphalt (HMA).
Air voids content that is either too high or too low can negatively impact pavement
life and lead to deteriorations such as fatigue cracking, rutting, raveling, bleeding, and
moisture damage. Currently destructive testing, such as coring, is typically conducted to
evaluate in-situ air voids content of placed HMA. Asphalt coring, by its nature, is highly
localized and therefore can easily miss localize areas of low quality. In addition, in large
projects, there are some concerns expressed on the aesthetic deficiencies with respect
to the number of cores in the wearing course and the introduction of potential weak
spots within the pavement structure. In other methods of air voids determination, such
as nuclear density gauge, there are also concerns regarding safety, costs associated with
radioactive material licensing and requirements for closing off work areas. In this paper
the use of a “GSSI PaveScan RDM” GPR model for non-destructive assessment of insitu
air voids in HMA is investigated. In-situ air voids content can be determined through
plotting of dielectric changes with measured cores’ air voids content. This technique
provides an opportunity for continuous measurement of air voids in HMA and, at the
same time, faster and reliable in-situ data for QA/QC. These benefits can significantly
accelerate pavement construction and so this paper looks to proliferate the adoption of
such practice. The case study on Al Khor Expressway, one of the major expressways
in Qatar, has demonstrated good repeatability and correlation with measured air voids
content."
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- Theme 2: Materials and Transportation Engineering [43 items ]