Nondestructive Testing Of Pavements Research Articles

Vehicle based system for continuous non-contact surface wave testing of pavements in 50 km/h

Non-destructive seismic surface wave measurements can be used for quality control of civil engineering infrastructures such as pavements and bridges. The seismic wave speed is directly linked to the dynamic E-modulus of asphalt concrete providing valuable information for quality control of both old and new structures. Non-destructive pavement testing is here demonstrated using a vehicle based system for continuous non-contact surface wave testing of pavements in about 50 km/h. A 48-channel air-coupled microphone array is mounted on the tow bar of a normal car along with a surface temperature IR sensor and GPS. Two metal heads on plastic strips are bouncing on the surface while driving producing high frequency (5-40 kHz) seismic waves in the asphalt concrete. Results demonstrate that the system can record continuous repeatable surface wave measurements with about two measurement points per meter while driving in a speed of 50 km/h. This measurement system opens up the possibility to perform faster and more economically efficient automated measurements with minimal disruption of traffic.

Development and application of a non-destructive pavement testing system based on linear structured light three-dimensional measurement

Automatic detection dramatically improves the efficiency and accuracy of asphalt pavement inspection. However, the existing detection systems cannot coordinate the balance between efficiency and accuracy. Three-dimensional pavement detection was proposed and developed in this article. The theoretical model of camera imaging was first established based on optical triangulation. The camera’s intrinsic and extrinsic parameters were evaluated by utilizing a checkerboard calibration target, and the camera lens distortion was also considered to ensure the accuracy of the three-dimensional measurements. The subpixel coordinates of the single-stripe center were extracted based on two-dimensional image processing technology, and then the pixel coordinates were converted into real-world elevation coordinates based on the camera imaging model. The cubic spline method and the three-dimensional data filtering method based on the pavement surface profile were applied to restore the data and remove the noise, respectively. Then the three-dimensional reconstruction was achieved based on Delaunay triangulation algorithm. We expect that this new system can significantly reduce the costs without decreasing the test accuracy, thus making large-scale engineering applications viable.

3D simulation of deflection basin of pavements under high-speed moving loads

The nondestructive testing of pavements currently has become more focused on continuous deflection profiles and vehicle moving speeds, which are recognized to be critical in obtaining complete and accurate pavement responses and conditions. However, current techniques cannot produce satisfactory results in terms of continuous deflection profiles at high-speed moving loads. Under this circumstance, the computational simulation is a good alternative. The objective of this study is to utilize the three-dimensional (3D) finite element (FE) analysis to investigate the characteristics of deflection basins of pavements under high-speed moving loads. Specifically, a 3D FE pavement model is constructed with six sets of pavement materials representing six types of pavements and four moving speeds (24 km/h, 40 km/h, 64 km/h, and 80 km/h). The results demonstrate that the deflection basin of a pavement exhibits an asymmetric shape under a high-speed moving load. It also reveals that there is a time lag between the maximum deflection and the center of the load in flexible pavements. This time lag is utilized to define a new term of “lag angle”. The effects of the material viscoelasticity, structural inertia damping, moving speed, and pavement deterioration conditions on the shape and lag angle of the deflection basin are illustrated. Furthermore, it is found that the lag angle of the deflection basin is closely related to the phase angle of the viscoelastic pavement materials. Finally, the deflection basins predicted by the 3D FE analysis are proven to be comparable to the field deflections obtained at a high moving speed.

Improving the GPR Detectability Using a Novel Loop Bowtie Antenna

The Ground Penetrating Radar (GPR) technique finds immense applications in civil engineering today, as the most suitable approach for non-destructive testing of pavements, highways, concrete structures, and more. The major challenge in carrying out a GPR evaluation is that the properties of the probed medium are usually unknown. The permittivity and conductivity of the medium may vary from those of air to water. The electromagnetic waves also have a frequency dependent attenuation. The ability of GPR to detect signals reflected and scattered by the targets largely depends upon the antenna performance. This paper studies a novel 11:1 wideband loop bowtie antenna with very good radiation properties in the entire operating bandwidth. Synthetic and experimental results are presented for the return loss and gain of the antenna. Furthermore, experimental results are presented for the radiation patterns in the E- and H-plane. We also used the antenna to measure B-scans over two different pipes, a bamboo, and a reinforced concrete structure. All results obtained with the proposed antenna have been compared with results obtained by using a RC loaded antenna. It has been found that the loop bowtie antenna has excellent detection capability and produces less clutter. The loop loading technique can be applied to existing antennas for improved GPR imaging. This will improve the detectability of GPR by improving the target return signal.

Application of 2D elastic Rayleigh waveform inversion to ultrasonic laboratory and field data

ABSTRACTIn addition to geophysical applications from the near surface to a global scale, seismic full‐waveform inversion can be applied to ultrasonic data on the centimetre and decimetre scales for nondestructive testing of pavements, facades, plaster, sculptures, and load‐bearing structures such as pillars or core samples from boreholes, which can consist of geo‐materials and non‐geomaterials. Classical non‐destructive testing approaches are based on the inversion of body‐wave travel times to deduce P‐wave velocity models. In contrast, surface waves (especially Rayleigh waves) are well suited to quantify surficial alterations of material properties, e.g., due to weathering. Furthermore, ultrasonic measurements of test samples with known material parameters close the gap between synthetic tests or analytical solutions and field data applications to estimate the accuracy of seismic modelling and inversion codes. Due to the scale invariance of the problem, the full‐waveform‐inversion approaches developed on the ultrasonic scale are also applicable to larger scale geophysical problems. In this paper, we demonstrate the potential of two‐dimensional Rayleigh waveform inversion on the ultrasonic scale using two data examples acquired with a single‐fold, low‐coverage acquisition geometry. For a simple homogeneous Plexiglas block in a controlled laboratory environment, we discuss the accuracy of visco‐elastic Rayleigh wave modelling, as well as the sensitivity of two‐dimensional elastic full‐waveform inversion with respect to small data residuals. While the inversion is restricted to the recovery of the S‐wave velocity model, a passive visco‐elastic modelling approach with a homogeneous average ‐model is required in order to describe amplitude loss and dispersion of the Rayleigh wave. The applicability of this approach under field conditions is illustrated for an ultrasonic data example from the weathered sandstone facade of the Porta Nigra in Trier (Germany). In addition to a random medium resolution analysis of the full‐waveform‐inversion result, we particularly emphasise the importance of lateral model smoothing to mitigate small‐scale inversion artefacts and to avoid erroneous interpretations. The estimated two‐dimensional S‐wave velocity anomalies correlate well with prominent surficial weathering effects in the upper about 3 cm.

FINITE ELEMENT BASED ADAPTIVE NEURO‐FUZZY INFERENCE TECHNIQUE FOR PARAMETER IDENTIFICATION OF MULTI‐LAYERED TRANSPORTATION STRUCTURES

During the service life of a pavement, it is often required to conduct Non-destructive tests (NDTs) to evaluate its structural condition and bearing capacity and to detect damage resulting from the repeated traffic and environmental loading. Among several currently used NDT methods, the Falling Weight Deflectometer (FWD) is the most commonly used pavement NDT method applied by many transportation agencies all over the world. Non-destructive testing of pavements using FWD is typically accompanied by the prediction of the Young’s modulus of each layer of the pavement structure through an inverse analysis of the acquired FWD deflection data. The predicted pavement layer modulus is both an indicator of the structural condition of the layer as well as a required input for conducting mechanistic-based pavement structural analysis and design. Numerous methodologies have been proposed for backcalculating the mechanical properties of pavement structures from NDT data. This paper discusses the development of an Adaptive-Network-based Fuzzy Inference System (ANFIS) combined with Finite Element Modeling (FEM) for the inverse analysis of the multi-layered flexible pavement structures subjected to dynamic loading.

Surface wave testing of pavements.

Pavements are constructed using several layers of materials, and their durability depends on the quality of all of these strata. It is, therefore, valuable to be able to determine the properties of the layers nondestructively. A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. In this type of layered structure, the interaction of leaky Lamb waves in the embedded layers generates surface waves corresponding only to certain portions of the guided wave dispersion curves and branches measurable at the pavement surface. To resolve the different mode branches, the wavefield is measured at the surface by using a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The recorded data are transformed to a phase velocity spectrum, which is then inverted to give the layer properties using a global inversion algorithm. The theoretical background along with experimental results of the application to nondestructive testing of pavements will be presented. Ongoing research on noncontact air-coupled measurements is also demonstrated. This opens up the possibility for faster on-the-fly surface wave testing of pavement layers, since surface contact is no longer required.

Verification of falling weight deflectometer backanalysis using a dynamic finite elements simulation

Falling weight deflectometer (FWD) testing is probably the most widely used device for the non-destructive testing of pavements. In many cases, engineers use the FWD test data for the estimation of pavement material properties, assuming a quasi-static approach. Since the verification of such results is often necessary, a dynamic finite element (FE) approach can be used towards this goal. Analytically, data provided by static backanalysis is used as input for 2D and 3D dynamic FE modeling of the FWD test in order to calculate the expected deflection bowl. Comparison of the measured with the calculated deflection bowl may provide a strong indication for the validation of the backanalysed data. Investigation of the application of this approach using field data from new and existing asphalt pavements with two different FWDs and several backanalysis programs as well as data of laboratory tested cores is also presented and discussed.

Characterizing Asphalt Pavements for Performance

Having fast computers with lots of memory makes it possible to make performance predictions using mechanics, which simply could not have been done even as recently as 3 or 4 years ago. This trend can be expected to continue. Pavement materials, whether asphalt concrete, base course, or subgrade, can now be characterized in realistic ways that were simply unavailable to pavement engineers. The dependence of these materials on stress state, moisture, temperature, strain rate, and damage is what has made their characterization difficult, if not impossible. This complexity has posed an almost insuperable problem for computational mechanics and for the linkage of these properties to construction specifications on the one hand and performance of in-service pavements on the other. Although these tasks will never be simple, the tools to work on them are becoming more adequate. Some examples are given of how one can proceed to simplicity through complexity in several areas that are important to pavement performance. In every case, one must be able to measure a property of the material that can be used as input to a computer program, principally a finite element program, that allows material properties to change from point to point. Several examples are given in the categories of material properties, material behavior, materials testing in the laboratory, nondestructive testing in the field, and performance prediction models. Laboratory testing, materials characterization and properties, nondestructive testing of pavements in service, construction specifications, pavement variability and reliability, field data collection, performance prediction modeling, and prediction of pavement response and distress with modern computer methods—taken individually, these subjects look complex. Combined with the glue of mechanics, they are simplicity itself. And they confirm Alfred North Whitehead’s principle, “The only simplicity that can be trusted is that which lies beyond complexity.”

Profiling Flexible Highway Pavement Continuously with Rolling Dynamic Deflectometer and at Discrete Points with Falling Weight Deflectometer

Nondestructive testing of pavements plays an important role in the management of pavement infrastructure. Nondestructive testing techniques have been widely utilized in the United States during the past decade to characterize pavement systems at discrete points. Discrete-point testing is, however, not feasible for routine use as a means of continuously characterizing pavement systems. A new nondestructive testing technique for continuously profiling pavements has been developed, namely, the rolling dynamic deflectometer (RDD). The RDD is a large truck on which a servohydraulic vibrator is mounted. The vibrator is used to apply large vertical dynamic loads to the pavement with loading rollers, and the induced dynamic displacements are measured at multiple locations with rolling sensors. This arrangement permits continuous measurements at multiple locations on the pavement surface in a fraction of the time required for typical discrete-point testing at a few points along the section. In this paper, the configuration of the RDD and the procedure used to analyze RDD data are discussed. Continuous deflection profiles are presented from a test section of a flexible Interstate highway pavement, which contains several distinctly different pavement structures. The effects of the structures on measured deflections are discussed, and the capability of the RDD to delineate the extent of each feature is presented. The importance of loading frequency and resonances in the pavement structure is shown. In addition, results from the RDD are compared with results from falling weight deflectometer (FWD) tests performed at the same locations.

Application of ground-penetrating radar and infrared thermography to pavement evaluation : Holt, F.B.; Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 105–115. American Society for Testing and Materials. (1989)

Application of ground-penetrating radar and infrared thermography to pavement evaluation : Holt, F.B.; Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 105–115. American Society for Testing and Materials. (1989)

Ground penetrating radar supplements deflection testing to improve airport pavements evaluations : Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 563–573. American Society for Testing and Materials. (1989)

Ground penetrating radar supplements deflection testing to improve airport pavements evaluations : Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 563–573. American Society for Testing and Materials. (1989)

Radar for pavement thickness evaluation : Maser, K.R.; Scullion, T.; Roddis, W.M.K.; Fernando, E. Nondestructive Testing of Pavements and Backcalculation of Moduli: Second Volume, Atlanta, Georgia (United States), 23–24 Jun. 1993. pp. 343–360. STP 1198 Edited by H.L. Von Quintus, A.J. Bush and G.Y. Baladi. ASTM (1994) ISBN 0-8031-1865-1

Radar for pavement thickness evaluation : Maser, K.R.; Scullion, T.; Roddis, W.M.K.; Fernando, E. Nondestructive Testing of Pavements and Backcalculation of Moduli: Second Volume, Atlanta, Georgia (United States), 23–24 Jun. 1993. pp. 343–360. STP 1198 Edited by H.L. Von Quintus, A.J. Bush and G.Y. Baladi. ASTM (1994) ISBN 0-8031-1865-1

Evaluation of NDT equipment for measuring voids under concrete pavements : Uddin, W.; Hudson, W.R. Nondestructive Testing of Pavements and Backcalculation of Moduli: Second Volume, Atlanta, Georgia (United States), 23–24 Jun. 1993. pp. 488–502. STP 1198 Edited by H.L. Von Quintus, A.J. Bush and G.Y. Baladi. ASTM (1994) ISBN 0-8031-1865-1

Evaluation of NDT equipment for measuring voids under concrete pavements : Uddin, W.; Hudson, W.R. Nondestructive Testing of Pavements and Backcalculation of Moduli: Second Volume, Atlanta, Georgia (United States), 23–24 Jun. 1993. pp. 488–502. STP 1198 Edited by H.L. Von Quintus, A.J. Bush and G.Y. Baladi. ASTM (1994) ISBN 0-8031-1865-1

Application of ground-penetrating radar and infrared thermography to pavement evaluation : Holt, F.B.; Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 105–115. American Society for Testing and Materials. (1989)

Application of ground-penetrating radar and infrared thermography to pavement evaluation : Holt, F.B.; Eckrose, R.A. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 105–115. American Society for Testing and Materials. (1989)

Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements : Al-Hunaidi, M O Can Geotech JV29, N3, June 1992, P506–511

Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements : Al-Hunaidi, M O Can Geotech JV29, N3, June 1992, P506–511

Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements

Spectral analysis of surface waves (SASW) is a nondestructive and in situ method for determining the stiffness profiles of soil and pavement sites. This method involves the generation and measurement of surface Rayleigh waves. By exploiting the dispersive characteristic of these waves in layered systems, the SASW method provides information on the variation of stiffness with depth. This paper presents the results of a case study for near-surface profiling of a pavement site using the SASW method. In this study, inconsistencies were observed in the dispersion curve of the site when the usual procedure of unfolding the relative phase spectrum was followed. A correction procedure to eliminate these inconsistencies is suggested and discussed. The thickness and wave velocities of the various layers obtained with the SASW method, after applying the correction procedure, matched closely those determined from cored samples and cross-hole tests. Key words : nondestructive testing, pavement, layered media, Rayleigh wave, spectral analysis, shear wave velocity, wave propagation.

Using NDT aided by an expert system to evaluate airport and highway systems : Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 525–539. American Society for Testing and Materials. (1989)

Using NDT aided by an expert system to evaluate airport and highway systems : Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 525–539. American Society for Testing and Materials. (1989)

Backcalculation of layer moduli from nondestructive pavement deflection data using the expert system approach : Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 341–354. American Society for Testing and Materials. (1989)

None of the existing backcalculation procedures is guaranteed to give a reasonable, effective elastic layer modulus for every deflection basin measured. The differences of results among various backcalculation programs are magnified by the differences if distinct analysts using the same program but applying different input parameters. A more experienced analyst often obtain better results. Some of the difficulties, such as the deviation of pavement material properties from the linear elastic, isotropic, and homogenous assumptions, the uncertainty of input parameters (for example, the deflection measurement), and the limitation of basin matching techniques, may only be dealt with by informed engineering judgment. A knowledge-based expert system approach as described in this paper may be used to generate more consistent and better estimations of in situ pavement material properties by combining numerical computations with a pavement experts knowledge and judgment. A knowledge base which serves as an intelligent pre- and postprocessor to the backcalculation program is developed. The knowledge base may be revised easily as better understanding emerges.

Using NDT aided by an expert system to evaluate airport and highway systems : Greenstein, J.; Berger, L. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 525–539. American Society for Testing and Materials. (1989)

Using NDT aided by an expert system to evaluate airport and highway systems : Greenstein, J.; Berger, L. Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026. Bush, A.J. and Baladi, G.Y. (Ed.) pp. 525–539. American Society for Testing and Materials. (1989)