posted on 2008-08-14, 09:22authored byRobert D. Evans, Matthew FrostMatthew Frost, Neil Dixon, Martyn Stonecliffe-Jones
The use of geophysical techniques to assess geotechnical and pavement structures can provide
much useful information to the engineer. The development of ground penetrating radar (GPR) in recent years
has led to its increasing use for pavement and geotechnical investigations, and the technique involves recording
the amplitude and travel time of electromagnetic GPR signals reflected from features within the
ground or structure of interest. Depths can be determined, and features of interest such as different layers, excess
moisture, voids and changes in materials can be identified. The interpretation of GPR data depends
largely on the ‘dielectric constant’ of the material(s), which governs the passage of GPR signals through a
material and the amount of signal energy reflected from features within a structure.
This paper reports an investigation of pavement material samples, conducted under controlled conditions, using
GPR. The effect of changes in material moisture and temperature on the dielectric constant, and hence the
passage of GPR signals, was investigated. Core samples of bituminous material obtained from highway pavement
sites were used to conduct a series of laboratory tests, in which the temperature of the material was controlled
in the range from -5 to +45 degrees C, and the dielectric constant and GPR signal velocity were determined.
Also, the materials dielectric constant and signal velocity were determined under dry and soaked
moisture conditions.
The test programme allowed an assessment of the effect of changes in materials temperature and moisture
condition to the response of data obtained during GPR investigations. The results of the testing showed that
both moisture and temperature can have a significant effect on the data obtained from GPR surveys of pavement
structures.
History
School
Architecture, Building and Civil Engineering
Citation
EVANS, R.D. ... et al, 2008. The response of ground penetrating radar (GPR) to changes in temperature and moisture condition of pavement materials. IN: Proceedings of the 1st International Conference on Transportation Geotechnics, 25th -27th August 2008, Nottingham, UK.