Jacek Sudyka

Typology of reflections in the assessment of the interlayer bonding condition of the bituminous pavement by the use of an impulse high-frequency ground-penetrating radar

This paper is devoted to the description of the double reflection type as an important basic case (as well as single reflection type) and gives some introduction to the phenomenology of elongated reflections in ground-penetrating radar (GPR) diagnostics of bituminous pavement. The single reflections correspond to simple velocity contrast between layers of medium while double reflections manifest interlayer delaminations or another thin laminas between two contacting layers of similar properties. Elongated reflection is a provisional name of large category of effects related to backscattering of the GPR impulse on strongly undulated boundary or on blurred boundary interface (thick zones), which have continuous vertical velocity stratification. The process of reflected signal formation during passage through this kind of boundary zone was illustrated by analogy of 1D waveform modelling. Numerous field examples were also discussed showing how the method allows to comment reflections properties in pavement diagnostic practice.

Alternative Approach for Interpreting Traffic Speed Deflectometer Results

This paper presents an alternative approach for interpreting data collected with the traffic speed deflectometer (TSD). Although the idea of measuring pavement deflections at traffic speeds in a continuous manner is not new, worldwide interest is recent, in part because of the availability of a commercial TSD device. As with any new device, there is a need for robust, scientifically sound, yet practical interpretation procedures. This paper describes the details of such a procedure recently developed at the Road and Bridge Research Institute in Poland. In addition to a detailed description of the proposed algorithm and its unique features, this study demonstrates an example application that uses data collected by the TSD operated by the Road and Bridge Research Institute. The proposed approach can be successfully applied to the TSD data and allows for deep customization for a users and customers needs and applications.

Reasons of premature cracking pavement deterioration: a case study

Cracking deterioration was observed on a motorway after only few years after construction. The motorway pavement was semi-rigid with a relatively thin thickness: 4 cm wearing layer, 11 cm asphalt base course, 20 cm lean concrete base course, 20 cm cement stabilized base course, 20 cm drainage layer, subgrade. lean concrete base course was cut in spacing 2,5 m to reduce the reflective cracking in asphalt layers. Testing program included: coring and materials composition testing, FWD testing to evaluate pavement layers stiffness modulus, radar testing to measure layer thickness, and to detect water presence in pavement layers, evaluation of cracks type and spacing, interlayer bond testing, low temperature resistance of asphalt wearing course. Testing results led to following conclusions: extremely low winter temperature in combination with relatively thin pavements thickness and semi-rigid pavement type was the reason of transverse cracking, longitudinal cracking observed on one of the sections were evaluated as top-down fatigue type cracking, low interlayer bond between asphalt base layers was one of the main reason of lower fatigue resistance of the pavement, lack of drainage in motorway median caused the presence of water in the pavement layers, and increased the danger of premature pavement deterioration, unpredicted increase in road traffic caused longitudinal top-down fatigue cracking.

Efficiency of 3D imaging in GPR diagnostics of joints and vertical construction contacts

The paper discusses the diagnostic abilities of the 3D imaging GPR technique on a practical level, applied to data collected by frequency-domain equipment in reflection configuration and visualized using the method of horizontal slices. This method is particularly efficient in the detection of reinforcement and large infrastructural objects of linear shape. It is especially interesting that the method also allows for the detection of joints and cracks, which are characterized by very weak GPR response. In this case several questions appear as to the nature of response generation and the features of the medium structure which are represented in the scattered signal. The scanned pavement has several layers of different ages and construction styles, and the GPR record illustrates large efficiency of this technique in diagnostics of the joint networks hidden below the asphalt overlay. The example proves reliability of the weak response corresponding to the top of the joints. Some problems related to chronology of responses corresponding to different depth of the medium were discussed. A specific asymmetric response corresponding to two horizontally layered constructions contacting along vertical plane was noted and described as well.