Khazanovich, Lev

Benefits from a potential significant correlation between distresses and slab thickness can be broadly applied in all stages of highway development from design and construction to maintenance decisions. In order to comprehensive explore this possibility, thickness data and existing distresses were related for three highway projects in Minnesota. Thickness was obtained through non-destructive ultrasonic testing, while distresses were recorded for the same location with a distress image software. Significant thickness variation was observed in both longitudinal and transverse directions. The combined results of thickness, shear wave velocity and distresses analysis revealed that an increase in shear wave velocity was coincident with a less damaged pavement area within a section. An in-depth statistical analysis confirmed this observation showing that shear surface velocity variation was better correlated with overall pavement performance than thickness variation. Differences in cracking behavior within a section were traced back to changes in construction and design practices, showing the potential of using shear velocity analysis for pavement maintenance. A survey and analysis procedure for shear wave velocity testing of concrete pavements is proposed.

The current empirical methods for determining traffic-opening criteria can be overly conservative causing unnecessary construction delays and user costs. The research described here recommends innovative mechanisticbased procedures for monitoring concrete early age development and evaluating the effect of early traffic opening on long-term damage accumulation. The procedure utilizes recent developments in nondestructive testing to optimize traffic opening timing without jeopardizing pavement longevity. These tasks were achieved via extensive field and laboratory experiments allowing for the analysis of variables such as curing condition and loading type with respect to the effect of early loading of concrete. The results of these efforts culminated in the development of a program that analyzes the effect of design and opening time decisions on pavement damage. The deliverable can be utilized by transportation agencies to make more informed decisions.

This document is an extensive review of full-depth permeable pavements including porous asphalt, pervious concrete, and permeable interlocking concrete pavers (PICP). Also included is a brief section on articulated concrete blocks/mats. The main topics, which have been divided into chapters, include structural and mix design, hydrologic design, hydraulic performance (i.e. infiltration capacity), maintenance needs/frequency/actions, the impact of permeable pavement on water quality, results of a highway shoulder feasibility study, knowledge gaps, and several cold climate case studies from the United States and Canada. While progress has recently been made with the relatively new permeable pavement technology, researchers have also identified many unresolved issues that are not well understood. These include a methodology to measure subgrade infiltration rates, filling data gaps related to structural integrity, construction, and related issues associated with permeable pavements, determining what maintenance activities are most effective on various pavement types and how frequently specific maintenance actions should be performed, a better understanding of the processes involved in the observed reduction of contaminant concentrations in stormwater flowing through permeable pavements, and a better understanding of the performance of permeable pavements over a time frame that better corresponds with a life-span of 20 years.

The project "Simplified Design Table for Minnesota Concrete Pavements" led to the creation of MnPCC-ME, a standalone 32-bit Windows executable program to replace the preexisting RigidPave. Whereas RigidPave was based upon the outdated AASHTO 1993 design procedure for rigid pavements, MnPCC-ME is based on MEPDG version 1.1, a mechanistic-empirical design procedure that accounts for the effects of traffic loading and environment. Furthermore, MnPCC-ME was localized for Minnesota pavements through: 1) the use of local climate data and weigh-in-motion traffic data; 2) the incorporation of previously conducted calibrations of the MEPDG for Minnesota pavements; and 3) the inclusion of advanced analysis features included in MnPCC-ME's flexible design counterpart, MnPAVE. The development and source code of MnPCC-ME is detailed in this final report.

Minnesota counties and the Minnesota Department of Transportation (MnDOT) use the Dynamic Cone Penetrometer (DCP) and the Lightweight Deflectometer (LWD) for in situ evaluation of stiffness and strength of soil and aggregate bases. The in situ test of choice (DCP or LWD) varies somewhat by county and region, depending partly on the local soil conditions and partly on historical preferences. The LWD is considered a measure of modulus while the DCP is considered a measure of shear strength. Recent field and laboratory tests have provided calibration for these tests for several specific granular samples. However, the results are likely less reliable for a broader range of potential granular materials used for granular bases. The objective of this research is to build on a mechanistic model developed for dry aggregate bases under LRRB INV 850 to increase its applicability to more materials and tests used in Minnesota. There were three primary thrusts to these new additions: (1) A model for the LWD test has been added so that computational predictions for DCP tests could be compared with those from LWD tests; (2) Particle-scale models for moisture and fine particle content have been included for the user to input these among the other existing material input parameters, and (3) Analogous algorithms have been developed for the DCP and LWD tests to be used with PFC3D, a commercial code maintained by Itasca Consulting Group.

The report describes the construction and design of composite pavements as a viable design strategy to use an asphalt concrete (AC) wearing course as the insulating material and a Portland cement concrete (PCC) structural layer as the load-carrying material. These pavements are intended for areas with heavy trucks and problem soils to increase the service life and minimize maintenance. The project focused specifically on thermally insulated concrete pavements (TICPs) (that is, composite thin AC overlays of new or structurally sound existing PCC pavements) and developed design and construction guidelines for TICPs. Specific research objectives include determining behavior of the layers of the TICP system, understanding life-cycle costs and the feasibility of TICPs, and incorporating the results into design and construction guidelines. Both construction and design guidelines are considered in light of the construction and performance of TICP test sections at the Minnesota Road Research project (MnROAD).

The effects of farm equipment on the structural behavior of flexible and rigid pavements were investigated in this study. The project quantified the difference in pavement behavior caused by heavy farm equipment as compared to a typical 5-axle, 80 kip semi-truck. This research was conducted on full scale pavement test sections designed and constructed at the Minnesota Road Research facility (MnROAD). The testing was conducted in the spring and fall seasons to capture responses when the pavement is at its weakest state and when agricultural vehicles operate at a higher frequency, respectively. The flexible pavement sections were heavily instrumented with strain gauges and earth pressure cells to measure essential pavement responses under heavy agricultural vehicles, whereas the rigid pavement sections were instrumented with strain gauges and linear variable differential transducers (LVDTs). The full scale testing data collected in this study were used to validate and calibrate analytical models used to predict relative damage to pavements. The developed procedure uses various inputs (including axle weight, tire footprint, pavement structure, material characteristics, and climatic information) to determine the critical pavement responses (strains and deflections). An analysis was performed to determine the damage caused by various types of vehicles to the roadway when there is a need to move large amounts agricultural product.

This report documents the development of a procedure to determine the structural adequacy and need of seasonal axle load restrictions for Minnesota low-volume roads. This procedure has been implemented into a new program, TONN2010. Since it is anticipated that the results of this study will be widely used by Mn/DOT, city, and county engineers, as well as consulting engineers involved in analysis of the falling weight deflectometer (FWD) data collected by the transportation agencies, an emphasis was made on development of a simple, easy to implement procedure. To simplify the procedure's implementation, the number of inputs was minimized. TONN2010 utilizes pavement layer thicknesses, FWD deflection basins, air temperature of the previous day, pavement surface temperature at the time of testing, pavement location, and anticipated traffic. All the inputs required by TONN2010 can be easily obtained by the user. Using these inputs, TONN2010 proceeds to 1) backcalculate layer moduli using the backcalculation procedure developed in this study, 2) adjust the backcalculated moduli using MnPAVE temperature and seasonal adjustment factors, and 3) estimate pavement axle load capacity by mechanistic-empirical analysis. In addition to detailing TONN2010, the report further describes selection of the damage models, development of the backcalculation design procedure, determination of the critical structural responses, development of new structural rating indexes, and finally the calibration and validation of the proposed procedure.

Several tests are used for characterizing unbound granular materials for pavement applications. The California Bearing Ratio (CBR), resilient modulus (MR), Dynamic Cone Penetrometer (DCP) tests are three of the most common tests used for this purpose. The objective of this research is twofold. The first is to develop numerical models for these three tests. The second is to investigate relationship between basic material properties, boundary conditions, and test results, ultimately, to develop a physics-based correlation between these tests. A 3-D discrete element method (DEM) based model is adapted to simulate these tests. Good agreement is observed between the results of the simulations and sample numerical and experimental studies on granular materials. The DEM code is used to determine effects of aggregate shape, coefficient of friction, gradation, stiffness and other details on test results. The model is also used to investigate statistics of inter-particle interaction between the granular particles.

The recently introduced Mechanistic-Empirical Pavement Design Guide (MEPDG) and related software provide capabilities for the analysis and performance prediction of different types of flexible and rigid pavements. An important aspect of this process is the evaluation of the performance prediction models and sensitivity of the predicted distresses to various input parameters for local conditions and, if necessary, re-calibration of the performance prediction models. To achieve these objectives, the Minnesota Department of Transportation (MnDOT) and the Local Road Research Board (LRRB) initiated a study "Implementation of the MEPDG for New and Rehabilitated Pavement Structures for Design of Concrete and Asphalt Pavements in Minnesota." This report presents the results of the evaluation of default inputs, identification of deficiencies in the software, sensitivity analysis, and comparison of results to the expected limits for typical Minnesota site conditions, a wide range of pavement design features (e.g. layer thickness, material properties, etc), and the effects of different parameters on predicted pavement distresses. Since the sensitivity analysis was conducted over a span of several years and the MEPDG software underwent significant modifications, especially for flexible pavements, various versions of the MEPDG software were run. Performance prediction models of the latest version of the MEPDG 1.003 were evaluated and modified or recalibrated to reduce bias and error in performance prediction for Minnesota conditions.