Time domain reflectometry (TDR) based moisture monitoring system for unbound granular pavements

Water in unbound granular pavements has a significant effect on pavement performance, particularly strength and rut resistance. Therefore measurement of the moisture content of these pavements provides valuable information to evaluate road conditions and construction quality, including the potential to aid in managing flood events and associated road closures. Time domain reflectometry (TDR) is a method of determining the electrical characteristics of a transmission line consisting of a probe embedded in a material by measuring the reflected wave forms. This is of interest in pavement engineering because it can be used to measure the change in water content of a granular material by observing the change in the dielectric permittivity of a soil around a TDR probe. TDR moisture probes have been widely used in homogeneous fine grained soils and sand for some time, however their use in unbound crushed rock road base material has not been widely documented. As a result there is minimal information on calibrating TDR probes for this type of material. This paper presents the methodology and results of a TDR probe calibration for granular road base material using laboratory experimental results as a part of current Austroads research on unbound granular materials. Multiple slabs of the materials were prepared at known densities and different moisture contents. The TDR wave form was analysed to determine dielectric permittivity which was then used with the moisture content of oven-dried samples to develop a relationship between dielectric permittivity and the moisture content of the material. This method of moisture monitoring can be set-up during pavement construction and can be easily set-up to provide a remote real-time, non-destructive moisture monitoring of unbound granular materials during construction and dry-back or over the entire life of the road. The relationship determined for typical pavement materials can also be used for ground penetrating radar (GPR) road surveys in the future.

• Record URL:
  http://arrbknowledge.com
• Authors:
  • Hore-Lacy, W
  • Bodin, D
  • Scheuermann, A
• Conference:
  • ARRB Conference, 26th, 2014, Sydney, New South Wales, Australia
• Publication Date: 2014-10

Language

• English

Media Info

• Pagination: 13p
• Serial:
  • Issue Number: 5.1

Subject/Index Terms

• TRT Terms: Base course (Pavements); Calibration; Granular soils; Materials tests; Moisture content; Monitoring; Pavement components; Pavements; Surveillance; Test procedures
• Uncontrolled Terms: Pavement technology
• ATRI Terms: Calibration; Granular; Material testing; Moisture content; Monitoring; Pavement materials; Roadbase
• ITRD Terms: 4107: Granular
• Subject Areas: Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I33: Other Materials used in Pavement Layers;

Filing Info

• Accession Number: 01548013
• Record Type: Publication
• Source Agency: ARRB
• Files: ITRD, ATRI
• Created Date: Dec 17 2014 10:50AM