A Rolling Dynamic Deflectometer (RDD) is a nondestructive testing device for determining continuous deflection profiles of pavements. Unlike discrete testing methods, the RDD performs continuous measurements. The ability to perform continuous measurements makes the RDD a powerful screening/evaluation tool for quickly characterizing large sections of pavement, with little danger of missing critical pavement features. RDD testing applications have involved pavement forensic investigations, delineations of areas to be repaired, selection of rehabilitation treatments, measurements of relative improvements due to the rehabilitation, and monitoring of changes with time (trafficking and environmental loading). However, the speed of RDD testing with the current rolling sensors is between 1 and 2 mph (1.6 to 3.2 km/hr). Improvements in testing speed and data analysis procedures would increase its usefulness in project-level studies as well as permit its used in some pavement network-level studies. A three-part study was carried out to further improve the RDD. The first part involved the development of speed-improved rolling sensors (referred as the third-generation rolling sensor). Key benefits of this new rolling sensor are: (1) increased testing speed up to 5 mph (8.0 km/hr), and (2) reduced level of rolling noise during RDD measurements. With this rolling sensor, the RDD can collect more deflection measurements at a speed of 3 to 5 mph (4.8 to 8.0 km/hr). Field trials using the first- and third-generation rolling sensors on both flexible and rigid pavements were performed to evaluate the performance of the third-generation rolling sensor. The second part of this study involved enhancements to the RDD data analysis procedure. An alternative data analysis method was developed for the third-generation rolling sensor. This new analysis method produces results at higher speeds that are comparable to the existing analysis method used for testing at 1 to 2 mph (1.6 to 3.2 km/hr). Key benefits of this analysis method that were not previously available are: (1) distance-based deflection profiles (report RDD deflections based on a selected distance interval), (2) improved-spatial resolution without sacrificing the filtering performance, and (3) analysis of the rolling noise characteristics and signal-to-noise and distortion ratios better characterize the deflection profiles and their accuracy. The third part of this study involved investigating the effects of parameters affecting RDD deflection measurements which include: (1) force level and operating frequency, (2) in-situ sensor calibration, (3) load-displacement curve, and (4) pavement temperature variations. These parameters need to be considered in testing and data analysis procedures of the RDD because small errors from these parameters can adversely influence calculations of the RDD deflections. Criteria are presented for selecting the best operating parameters for testing. / text

A Rolling Dynamic Deflectometer (RDD) is a nondestructive testing device for determining continuous deflection profiles of pavements. Theses deflection profiles can be used more effectively when combined with other data such as pavement thickness, variability in moisture and other subsurface conditions, void detection and pavement right-of-way conditions. Therefore, a new, multi-function pavement testing device has been developed by a joint effort between the Texas Department of Transportation (TxDOT), the Center for Transportation Research (CTR) at the University of Texas at Austin (UT) and the Texas A&M Transportation Institute (TTI) at Texas A&M University. This new device is called the Total Pavement Acceptance Device (TPAD). The objective of TPAD testing is to nondestructively and nonintrusively investigate the structural adequacy of the total pavement system. The multiple functions of the TPAD presently include the following measurement capabilities: (1) rolling dynamic deflectometer (RDD), (2) ground penetrating radar (GPR), (3) global positioning (GPS), (4) pavement surface temperature, (5) digital video imaging of pavement and right-of-way conditions and (6) longitudinal survey offsets from known points through distance measurement (DMI). The TPAD is currently designed to perform continuous measurements at speeds around 2 to 3 mph. The effort in this dissertation is directed at: (1) developing the fourth-generation rolling sensors for faster testing speeds with the TPAD, (2) developing the Jointed Concrete Pavement (JCP) testbed with known and well-documented conditions (3) developing and evaluating the TPAD mobile platform, (4) evaluating the performance of the fourth-generation rolling sensors and refining a field calibration procedure and (5) studying the influence of the longitudinal and transverse joints in Jointed Concrete Pavement on TPAD deflection profile measurements. The first part involved the study of previous research and preliminary testing using the second-generation rolling sensor. Key benefits of the fourth-generation rolling sensor are: (1) reduced rolling noise during the testing, (2) higher signal-to-noise ratio (SNR), and (3) better tracking of the sensor. The second part of this work involved the development of the JCP testbed at the Texas Department of Transportation (TxDOT), Flight Services Facility (FSF) adjacent to the Austin-Bergstrom International Airport (ABIA). The JCP testbed was developed to establish a pavement facility with known and well-documented conditions for use in future research dealing with rigid pavement testing. The third part of this work involved the acceptance testing of the TPAD mobile platform for the RDD deflection measurements. The mobile platform was the one of the key components to develop the new moving pavement testing device. The TPAD mobile platform was developed by modifying a small, off-road vibroseies built by Industrial Vehicle International, Inc. (IVI). Acceptance testing of each of the following components was performed: (1) automated speed control, (2) static loading system and (3) dynamic loading system. The fourth part of this work involved the TPAD deflection measurements at the testbed at the TxDOT FSF. The deflection profiles using the fourth-generation rolling sensors and TPAD were performed at the established testbed. During the performance evaluation testing, the new sensor positioning, towing and raising/lowering system was developed and installed in the TPAD. The fifth part of this study involved the deflection measurement using the TPAD-RDD system on the jointed concrete pavement. This study includes the repeatability of the TPAD deflection measurements, the influence of the proximity to the longitudinal and transverse joints in JCP on TPAD deflection measurements, deflection measurements under different pavement surface temperature, the characteristic of the TPAD-RDD deflections and the comparison between the Falling Weight Deflectometer and TPAD deflection measurement testing. / text