Author : Saarenketo T.
Description:Oulu University Press, 2006. 125 .The synopsis of this work begins with a presentation of the theory and basic principles of GPRtechniques. Special attention is given to the dielectric properties and seasonal changes of unboundroad materials and subgrade soils. The synopsis also presents different kinds of GPR hardwaresystems as well as recommendations and experiences from different data collection, processing andinterpretation techniques. Special attention is given to a method whereby GPR data is integrated withother road survey data and then analysed using a number of structural diagnostic methods. Finally,the synopsis provides an overview of of the various GPR applications on roads and streets, bridges,railways and airports.The laboratory test results presented in this work show that the relationship between dielectricvalue and increasing water content is not linear or exponential but more likely a series of logarithmicfunctions. Laboratory results also showed that dielectric dispersion, which can be related to poorlyperforming subgrade soils and road aggregates, takes place mainly in loosely bound adsorption waterand capillary water layer. As such these moisture sensitive problem materials can also be identifiedduring the dry summer seasons when they are stiff. Dielectric value and electrical conductivity canalso be related to other technical properties of road materials and subgrade soils such as frostsusceptibility, shear strength, plastic limit, compaction degree and voids content. Laboratory tests andfield data collected using the Percostation technique also demonstrate that a knowledge of seasonalchanges and thermodynamics is very important in understanding and modelling the mechanicalbehaviour of road structures. Finally, laboratory and field tests indicate that colloids have animportant role in the failure mechanism of the road materials.This research demonstrates that the GPR technique not only gives valuable structural informationon the different types of structures and subgrade soils but it provides a wide range of information ofthe electrical properties of the materials under survey which can be further related to their mechanicalperformance. The best information will be gained if GPR data is analysed together with other nondestructive testing data collected form the roads, railways and airports.ContentsIntroductionGPR principles and pulse propagationDielectric properties and seasonal changes of unbound road materials andsubgrade soilsGPR hardware and accessoriesGPR data collectionData processing and interpretationIntegrated GPR data analysis with other road survey dataGPR applications on roads and streetsBridgesRailwaysAirfieldsConclusions