Time Domain Reflectometry Measurements of Road Basecourse Moisture Content

This paper describes an empirical transform between the propagation time (tp) data obtained from a non invasive Time Domain Reflectometry (TDR) sensor to the percentage moisture content θ_v within two different road making basecourse aggregate material. Results show that a simple quadratic fit between t_p and θ_v can be given leading to a maximum error in the estimate of 0.55%. It is also shown that the dielectric model underlying each of the basecourses is different enough to warrant the use of a unique quadratic function (i.e. different quadratic coefficients) for each.