Khazanovich, Lev

It is well-known that longitudinal joint construction quality is critical to flexible pavement life. The maintenance activities caused by longitudinal joint deterioration's direct or indirect effects and raveling problems along the centerline paving joint of asphalt roadways have become challenging for many highway agencies. A poorly constructed joint can lead to premature deterioration of an otherwise sound pavement. Thus, improving the joint’s construction can improve density and decrease permeability. It is probably the single most crucial remedy to enhance pavement performance. A density profiling system (DPS) provides continuous, instead of limited, coverage provided by conventional joint quality evaluation methods. Statistical, probabilistic, and percent-within-limits (PWL) analysis of DPS data suggests avoiding the construction of an unconfined joint. Tapered joints, confined butt joints employing the Maryland method or otherwise, echelon paved, and unconfined butt joints with cut back can produce adequate compaction at the joint.

This paper presents the results of a blind test evaluation of various nondestructive testing techniques including well established methods such as chain dragging, rod sounding, and GPR as compared to an emerging ultrasonic array technology in determining the extent of the concrete joint deterioration. Nondestructive testing at two concrete pavement joints at MnROAD was performed and the results were independently evaluated and submitted to MnDOT. Significant discrepancies in subsurface deterioration assessments were observed among these techniques. Forensic evaluation (trenching and coring) were utilized to resolve the discrepancies in test results. It was concluded that the ultrasound array analysis was the only method able to accurately determine the horizontal extent of the deterioration otherwise undetected by the other available nondestructive evaluation methods. Additionally, ultrasonic tomography analysis was able to determine the depth of the deterioration. This makes this emerging technology an attractive alternative to traditional NDT methods for concrete pavement joint assessment. Paper submitted for the Transportation Research Board 92nd Annual Meeting, 13-17 January 2013.

The Minnesota Department of Transportation (Mn/DOT) began construction on the Minnesota Road Research Project (MnROAD) in 1991 and opened the full-scale pavement research facility to live traffic in 1994. Since the time of its construction, MnROAD, the first major test track since the AASHO Road Test of the 1950s and 1960s, has learned many lessons in pavement testing and pavement engineering on behalf of the greater pavement community. Researchers at the University of Minnesota reviewed these lessons from the first phase of MnROAD (the facility's first ten years of operation) for a project titled MnROAD Lessons Learned. The Lessons Learned project involved over fifty interviews, three hundred published and unpublished reports, papers, and briefs, and an online survey of pavement professionals. This paper, based on the Lessons Learned project, presents a sample of the lasting benefits of MnROAD at the local, state, and national levels. Furthermore, the paper provides extensive references for these benefits in hopes of increasing awareness of this pavement test facility's under-publicized contributions to pavement engineering. This paper was submitted for the Transportation Research Board 2008 Annual Meeting.

This is a project update on the work that became Report 2012-08, "Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance." It gives the status of the project after the testing had been completed, but before the final report was written.

Throughout its decade of operation, MnROAD has become a major resource in the pavement community for test track expertise, pavement data, and pavement research. However, one overlooked benefit of MnROAD’s first phase of operation is the effort of MnROAD engineers to introduce, develop, and encourage the use of new technologies and techniques for pavement engineers. While the list of new products tested and/or developed at MnROAD is extensive, this brief will focus on three products and the influence of those products outside of MnROAD: the Dynamic Cone Penetrometer, used to estimate the strength of subgrades; Ground Penetrating Radar, used in pavements to assess, among other things, layer thicknesses and subsurface conditions; and Continuous Compaction Control, which involves continuously measuring soil compaction and adjusting the needed force to compact the soil. These three highlights emphasize the ability of MnROAD to: 1. serve as a test facility for pavement and pavement foundation experiments, 2. develop new technologies and procedures for pavement engineering, 3. contribute in a significant manner to pavement engineering both at a local and national level. It is hoped that this brief exposes the reader not only to a few past accomplishments of MnROAD in new technologies but will give a better idea of the promise and ability of MnROAD in the development and adoption of these technologies.

This brief details that analysis for the mainline IRI data and discusses the development of MnDOT's IRI specifications and the use of MnROAD test sections to calibrate IRI test equipment.

In 1993, the Minnesota Department of Transportation (Mn/DOT) commissioned the University of Minnesota Department of Civil Engineering to develop, construct and evaluate a laboratory-based test facility for rapidly applying repeated heavy vehicle loads (simulated) to pavement test structures. The purpose of this facility was to efficiently and accurately evaluate the long-term performance potential of new and experimental highway pavement designs and materials. This facility was dubbed “Minnesota Accelerated Loading Facility” or “Minne-ALF.”

Due to an increase in demand to shorten construction time as much as possible, the purpose of this project was to determine the optimum strength for concrete pavement before opening it to traffic and without jeopardizing long-term performance. Six test cells in MnDOT's MnROAD project were constructed in 2017 with varying degrees of early loading. Various tests were performed during and immediately following construction and, four years later, ride quality and load transfer efficiency were used to quantify long-term damage. A finite element analysis was then performed using ISLAB2000 to determine the effects of load location and temperature gradient on the Portland cement concrete (PCC) longitudinal stresses to explain the absence of premature failure. A mechanistic-based early opening damage analysis procedure was created to determine the optimum timing for opening of a concrete pavement to traffic. The procedure accounts for the effect of site conditions and pavement characteristics. A web-based tool was developed to facilitate implementation of this procedure.

The objective of this research was to develop a procedure for nondestructive assessment of pavement thickness using 3D ground penetrating radar (3D GPR). The software developed in this study can analyze the data sets collected with either 27- or 121- transmitting and receiving pair configurations. It uses two approaches to determine asphalt thickness: analysis of individual pairs of antennas time histories along with the user-provided dielectric constant for the asphalt layer; and analysis of groups of signals from transmitting and receiving antennas with various spacing but with a common mid-point using the Modified Extended Common Mid-Point (MXCMP) method. The MXCMP method is a generalization of the Extended Common Mid-Point (MXCMP) method for analysis of more than two antenna pair signals with the same mid-point.

An unbonded portland cement concrete overlay of concrete pavements (UBOL) is a rehabilitation technique in which the new overlay is isolated from the existing distressed pavement using a separator layer. Typically; a 1-to 2-in asphalt separator layer (or interlayer) is used. Recent innovations in the unbonded overlay technology have led to the adoption of new types of interlayers; such as non-woven geotextile fabric; as well as the use of overlays with joint spacings and layouts that are much shorter than conventional joint spacings. The effect of these design alternatives on the performance of the UBOL cannot be accounted for using currently available design procedures. This report documents the development of a new mechanistic-empirical design procedure for UBOL. It presents the results of laboratory and field studies; the calibration of an advanced structural (Totski) model that better captures the effects of the interlayer and separation between the overlay and the existing pavement; and the development of cracking and faulting performance prediction models for UBOL. The performance prediction models were incorporated into a rudimentary software tool; Pitt UBOL-ME; that can be used for the design and analysis of UBOL. Unlike prior UBOL design procedures; Pitt UBOL-ME can be used to quantify the effect of the performance of the interlayer on the performance of the UBOL and can be used for both conventional and short joint spacings.