Master of Science / Department of Civil Engineering / Mustaque Hossain / The Kansas Department of Transportation is transitioning from adherence to the 1993 American Association of State Highway and Transportation Officials (AASHTO) Pavement Design Guide to implementation of the new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for flexible and rigid pavement design. This study was initiated to calibrate MEPDG distress models for Kansas. Twenty-seven newly constructed projects were selected for flexible pavement distress model calibration, 21 of which were used for calibration and six that were selected for validation. In addition, 22 newly constructed jointed plain concrete pavements (JPCPs) were selected to calibrate rigid models; 17 of those projects were selected for calibration and five were selected for validation. AASHTOWare Pavement ME Design (ver. 2.2) software was used for design analysis, and the traditional split sampling method was followed in calibration. MEPDG-predicted distresses of Kansas road segments were compared with those from Pavement Management Information System data. Statistical analysis was performed using the Microsoft Excel statistical toolbox. The rutting and roughness models for flexible pavement were successfully calibrated with reduced bias and accepted null hypothesis. Calibration of the top-down fatigue cracking model was not satisfactory due to variability in measured data, and the bottom-up fatigue cracking model was not calibrated because measured data was unavailable. AASHTOWare software did not predict transverse cracking for any projects with global values. Thus thermal cracking model was not calibrated. The JPCP transverse joint faulting model was calibrated using sensitivity analysis and iterative runs of AASHTOWare to determine optimal coefficients that minimize bias. The IRI model was calibrated using the generalized reduced gradient nonlinear optimization technique in Microsoft Excel Solver. The transverse slab cracking model could not be calibrated due to lack of measured cracking data.

Mechanistic-Empirical (M-E) methods are the cornerstone of current pavement engineering practice because of their enhanced predicting capabilities. Such predicting power demands richer input data, computational power, and calibration of the empirical components against distress measurements in the field. In an effort to spearhead the transition to M-E design in Uruguay, the aim of this Project is twofold: (1) develop an open-source, MEPDG-based, simplified M-E tool for Uruguayan flexible pavements [Product-One], and (2) compile a library of Uruguayan input data for design [Product-Two]. A functional, Matlab-based beta version of Product-One with default calibration parameters and a first collection of Uruguayan input data are presented herein. The Product-One beta is capable of designing hot-mix asphalt (HMA) structures over granular bases on top of the subgrade. Product-Two features climate information from the INIA weather station network, traffic distribution patterns for select Uruguayan highways, standard-based (Level-3) HMA properties, and Level-3 and Level-2 unbound materials' parameters. Product-One's outcomes were against other available M-E software, as a means to test the code's performance: Product-One reported a distress growth similar to CR-ME (MEPDG-based) on default calibration parameters but different to MeDiNa (calibrated core). In conclusion, Product-One managed to perform like another MEPDG-based software under the same design inputs and constraints, accomplishing one of this Thesis' objectives. However, Product-Two could not be created to the initially-desired extent. Nevertheless, the author remains confident that significant leaps forward can be made with little extra effort and further research on M-E design can be encouraged from this project. / Master of Science / The design of pavement structures historically relied on methodologies developed after experimental results, the so-called “empirical methods”. Advances in technology over the recent years allowed for more complex but more reliable methods – the mechanistic-empirical (M-E) methods – to finally be adopted by practitioners both in the US and abroad. In an effort to encourage the transition to M-E design in Uruguay, this project aimed at developing an open-source M-E design tool for Uruguayan flexible pavements based on the American MEPDG design methodology [Product-One], and assembling a library of Uruguayan data necessary for design with such an M-E method [Product-Two]. In this project, a beta version of the Product-One design tool for the design of asphalt-surfaced pavements and a collection of climate, traffic distribution, and materials’ properties data from Uruguayan sources for design is presented (load information was not available for this project); this Thesis is the log of the data collection effort as well as the guide to using and understanding all the components of Product-One. In addition, Product-One has been tested by comparing its pavement design results for a given Uruguayan highway against other M-E design software tools: MeDiNa and CR-ME. Product-One’s outcomes resembled the results given by CR-ME (also MEPDG-based) but differed with those from MeDiNa (crafted specifically for design of Brazilian roads). In conclusion, Product-One managed to perform like another MEPDG-based design tool under the same inputs and constraints, accomplishing one of this Thesis’ objectives. However, some of the Uruguayan information sought for could not be retrieved and so added to Product-Two. Anyway, the author remains confident that both Products can be significantly improved with little extra effort and that this project may encourage further research on M-E design.

The AASHTO 1993 Guide for Design of Pavement Structures is the most widely used pavement design method in both Canada and the United States, and is currently used by the Ministry of Transportation of Ontario (MTO) for both flexible and rigid pavement design. Despite its widespread use, the AASHTO 1993 pavement design method has significant limitations stemming primarily from the limited range of conditions observed at the AASHTO Road Test from which its empirical relationships were derived. The Mechanistic-Empirical Pavement Design Guide (MEPDG) was developed to address the perceived limitations of the AASHTO 1993 Guide. Although the MEPDG provides a rational pavement design procedure with a solid foundation in engineering mechanics, a considerable amount of work is required to adapt and validate the MEPDG to Ontario conditions. The purpose of this research was to conduct a comparative analysis of Ontario structural pavement designs using the AASHTO 1993 Guide for Design of Pavement Structures and the Mechanistic-Empirical Pavement Design Guide. Historical flexible, rigid, and asphalt overlay pavement designs completed using the AASHTO 1993 pavement design method for the MTO were evaluated using a two-stage procedure. First, the nationally-calibrated MEPDG pavement distress models were used to predict the performance of the pavements designed using the AASHTO 1993 method. The purpose of this stage of the analysis was to determine whether the two methods predicted pavement performance in a consistent manner across a range of design conditions typical of Ontario. Finally, the AASHTO 1993 and MEPDG methods were compared based on the thickness of the asphalt concrete or Portland cement concrete layers required to satisfy their respective design criteria. The results of the comparative analysis demonstrate that the AASHTO 1993 method generally over-predicted pavement performance relative to the MEPDG for new flexible pavements and asphalt overlays of flexible pavements. The MEPDG predicted that most of the new flexible pavements and asphalt overlays of flexible pavements designed using the AASHTO 1993 method would fail primarily due to permanent deformation and / or roughness. The asphalt layer thicknesses obtained using the MEPDG exceeded the asphalt layer thicknesses obtained using the AASHTO 1993 method, and a poor correlation was observed between the asphalt layer thicknesses obtained using the two methods. Many of the new flexible pavements and asphalt overlays of existing flexible pavements could not be re-designed to meet the MEPDG performance criteria by increasing the asphalt layer thickness. The results of the comparative analysis showed that the AASHTO 1993 method generally under-predicted rigid pavement performance relative to the MEPDG, although the results varied widely between alternative rigid pavement designs. The AASHTO 1993 rigid pavement designs that the MEPDG predicted would not meet the rigid pavement performance criteria generally failed due to pavement roughness. A very poor correlation was observed between the Portland cement concrete layer thicknesses obtained using the MEPDG and AASHTO 1993 design methods. The MEPDG predicted thinner Portland cement concrete layer thicknesses than the AASHTO 1993 design method for most of the rigid pavement designs.

Typical material used by the Tennessee Department of Transportation for highway bases was evaluated for application to the new Mechanistic-Empirical Pavement Design Guide. Two types of granular Tennessee highway base material were mixed with different stabilizers and tested in the lab according to AASHTO T-307 99 (2003). Unconfined Compressive Strength and California Bearing Ratio tests were also done in an effort to correlate these results with resilient modulus. Three different combinations of base and stabilizer were tested and modeling coefficients were produced. Base structural layer coefficients were generated and compared to coefficients currently in use by TDOT.

Typical material used by the Tennessee Department of Transportation for highway bases was evaluated for application to the new Mechanistic-Empirical Pavement Design Guide. Two types of granular Tennessee highway base material were mixed with different stabilizers and tested in the lab according to AASHTO T-307 99 (2003). Unconfined Compressive Strength and California Bearing Ratio tests were also done in an effort to correlate these results with resilient modulus. Three different combinations of base and stabilizer were tested and modeling coefficients were produced. Base structural layer coefficients were generated and compared to coefficients currently in use by TDOT.

Master of Science / Department of Civil Engineering / Mustaque Hossain / The AASHTO Guide for Design of Pavement Structures is the primary document used by the state highway agencies to design new and rehabilitated highway pavements. Currently the Kansas Department of Transportation (KDOT) uses the 1993 edition of the AASHTO pavement design guide, based on empirical performance equations, for the design of Jointed Plain Concrete Pavements (JPCP). However, the newly released Mechanistic-Empirical Pavement Design Guide (MEPDG) provides methodologies for mechanistic-empirical pavement design while accounting for local materials, environmental conditions, and actual highway traffic load distribution by means of axle load spectra. The major objective of this study was to predict pavement distresses from the MEPDG design analysis for selected in-service JPCP projects in Kansas. Five roadway sections designed by KDOT and three long term pavement performance (LTPP) sections in Kansas were analyzed. Project-specific construction, materials, climatic, and traffic data were also generated in the study. Typical examples of axle load spectra calculations from the existing Weigh-in-Motion (WIM) data were provided. Vehicle class and hourly truck traffic distributions were also derived from Automatic Vehicle Classification (AVC) data provided by KDOT. The predicted output variables, IRI, percent slabs cracked, and faulting values, were compared with those obtained during annual pavement management system (PMS) condition survey done by KDOT. A sensitivity analysis was also performed to determine the sensitivity of the output variables due to variations in the key input parameters used in the design process. Finally, the interaction of selected significant factors through statistical analysis was identified to find the effect on current KDOT specifications for rigid pavement construction. The results showed that IRI was the most sensitive output. For most projects in this study, the predicted IRI was similar to the measured values. MEPDG analysis showed minimal or no faulting and was confirmed by visual observation. Only a few projects showed some cracking. It was also observed that the MEPDG outputs were very sensitive to some specific traffic, material, and construction input parameters such as, average daily truck traffic, truck percentages, dowel diameter, tied concrete shoulder, widened lane, slab thickness, coefficient of thermal expansion, compressive strength, base type, etc. Statistical analysis results showed that the current KDOT Percent Within Limits (PWL) specifications for concrete pavement construction are more sensitive to the concrete strength than to the slab thickness. Concrete slab thickness, strength, and truck traffic significantly influence the distresses predicted by MEPDG in most cases. The interactions among these factors are also almost always evident.

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The perpetual structural pavement design is currently being explored for usage in Canada and worldwide. This thick structural design can provide many potential benefits but it also has associated costs. Cold Canadian winters and warm summers impact pavement performance and make pavement design challenging. This is further complicated by a heavy dependence on trucks to transport imports and exports. Consequently, most Canadian roads are subjected to rapid deterioration due to high fatigue stresses and rapid growth of the traffic loads. The concept of a perpetual pavement design was raised to overcome the limitation of structural capacity of the conventional pavement designs. The concept of perpetual pavement was explained and introduced in this thesis and the benefits behind the perpetual pavement construction were studied. The Ministry of Transportation of Ontario (MTO) and the Centre for Pavement and Transportation Technology (CPATT) joined their efforts in partnership with Natural Sciences and Engineering Research Council (NSERC), Ontario Hot Mix Producers Association (OHMPA), Stantec Consultant, McAsphalt and others to construct three test sections on the Highway 401. The goal was to monitor and evaluate the performance of three different pavement structural designs. Performance evaluation of test section was performed by evaluating the expected ability of pavement section to withstand the traffic loads and climate impact throughout the design life of that pavement section with minimum damage. The minimum damage is expressed as low vertical pressure on top of subgrade, low shear stresses in the surface course and low tensile strain at the bottom of asphalt layers. Perpetual pavement design with Rich Bottom Mix (RBM) layer, perpetual pavement design without RBM and a conventional pavement design were constructed and instrumented with various types of sensors. These are capable of monitoring the tensile strain in asphalt layers, vertical pressure on the subgrade surface, moisture in the subgrade material and the temperature profile in the pavement sections. The test section construction, sensor installation and preliminary modeling are all part of this thesis. Preliminary structural evaluation was performed by analyzing the three designs using a Mechanistic Empirical Pavement Design Guide (MEPDG) model representing the three pavement designs constructed on the Highway 401. In addition, the WESLEA for Windows software was used to validate the long life performance of the perpetual pavement design. Life Cycle Cost Analysis (LCCA) was also performed for the perpetual and conventional pavement designs to evaluate the cost benefits associated with pavement designs for 70 year analysis period. In addition, the perpetual Pavement design philosophy for moderate and low traffic volume roads was also examined in this research. This pavement design involved creating a complete comparison and validation of the benefits of using perpetual asphalt pavements versus the conventional pavements in all road types and traffic categories. Structural evaluation of the pavement sections in moderate and low traffic volume roads was performed. In addition, LCCA was implemented to validate the perpetual and conventional structural pavement designs in moderate and low traffic volume roads.