Compaction is the process of reducing the volume of hot-mix asphalt (HMA) by the application of external forces. As a result of compaction, the volume of air voids decreases, aggregate interlock increases, and interparticle friction increases. The quality of field compaction of HMA is one of the most important elements influencing asphalt pavement performance. Poor compaction has been associated with asphalt bleeding in hot weather, moisture damage, excessive aging and associated cracking, and premature permanent deformation. This study was conducted to develop a model within the context of a thermomechanical framework for the compaction of asphalt mixtures. The asphalt mixture was modeled as a nonlinear compressible material exhibiting time-dependent properties. A numerical scheme based on finite elements was employed to solve the equations governing compaction mechanisms. The material model was implemented in the Computer Aided Pavement Analysis (CAPA-3D) finite-element (FE) package. Due to the difficulty of conducting tests on the mixture at the compaction temperature, a procedure was developed to determine the model's parameters from the analysis of the Superpave® gyratory compaction curves. A number of mixtures were compacted in the Superpave® gyratory compactor using an angle of 1.25 degrees in order to determine the model's parameters. Consequently, the model was used to predict the compaction curves of mixtures compacted using a 2-degree angle of gyration. The model compared reasonably well with the compaction curves. FE simulations of the compaction of several pavement sections were conducted in this study. The results demonstrated the potential of the material model to represent asphalt mixture field compaction. The developed model is a useful tool for simulating the compaction of asphalt mixtures under laboratory and field conditions. In addition, it can be used to determine the influence of various material properties and mixture designs on the model's parameters and mixture compactability.
This textbook lays out the state of the art for modeling of asphalt concrete as the major structural component of flexible pavements. The text adopts a pedagogy in which a scientific approach, based on materials science and continuum mechanics, predicts the performance of any configuration of flexible roadways subjected to cyclic loadings. The authors incorporate state-of the-art computational mechanics to predict the evolution of material properties, stresses and strains, and roadway deterioration. Designed specifically for both students and practitioners, the book presents fundamentally complex concepts in a clear and concise way that aids the roadway design community to assimilate the tools for designing sustainable roadways using both traditional and innovative technologies.
This book summarizes research being pursued within the Research Unit FOR 2089, funded by the German Research Foundation (DFG), the goal of which is to develop the scientific base for a paradigm shift towards dimensioning, structural realization and maintenance of pavements, and prepare road infrastructure for future requirements. It provides a coupled thermo-mechanical model for a holistic physical analysis of the pavement-tire-vehicle system: based on this model, pavement structures and materials can be optimized so that new demands become compatible with the main goal – durability of the structures and the materials. The development of these new and qualitatively improved modelling approaches requires a holistic procedure through the coupling of theoretical numerical and experimental approaches as well as an interdisciplinary and closely linked handling of the coupled pavement-tire-vehicle system. This interdisciplinary research provides a deeper understanding of the physics of the full system through complex, coupled simulation approaches and progress in terms of improved and, therefore, more durable and sustainable structures.
The micro- and nano-modification of infrastructure materials and the associated multi-scale characterization and simulation has the potential to open up whole new uses and classes of materials, with wide-ranging implications for society. The use of multi-scale characterization and simulation brings the ability to target changes at the very small scale that predictably effect the bulk behavior of the material and thus allowing for the optimization of material behavior and performance. The International RILEM Symposium on Multi-Scale Modeling and Characterization of Infrastructure Materials (Stockholm, June 10-12, 2013) brought together key researchers from around the world to present their findings and ongoing research in this field in a focused environment with extended discussion times. From asphalt to concrete, from chemistry to mechanics, from nano- to macro-scale: the collection of topics covered by the Symposium represents the width and depth of the currently ongoing efforts of developing more sustainable infrastructure materials. Researchers, practitioners, undergraduates and graduate students engaged in infrastructure materials or multi-scale characterization and modeling efforts can use this book as a comprehensive reference, to learn about the currently ongoing research efforts in this field or as an inspiration for new research ideas to enhance the long-term performance of infrastructure materials from a fundamental perspective. The Symposium was held under the auspices of the RILEM Technical Committee on Nanotechnology-Based Bituminous Materials 231-NBM and the Transport Research Board (TRB) Technical Committee on Characteristics of Asphalt Materials AFK20.
TRB’s National Cooperative Highway Research Program (NCHRP) Report 719: Calibration of Rutting Models for Structural and Mix Design highlights proposed revisions to the Mechanistic–Empirical Pavement Design Guide (MEPDG) and software to incorporate three alternative rut-depth prediction models that rely on repeated load (triaxial) permanent deformation or constant height testing to provide the requisite input data.
This textbook teaches the basic concepts and methods of project management but also explains how to convert them to useful results in practice. Project management offers a promising working area for theoretical and practical applications, and developing software and decision support systems (DSS). This book specifically focuses on project planning and control, with an emphasis on mathematical modeling. Models and algorithms establish a good starting point for students to study the relevant literature and support pursuing academic work in related fields. The book provides an introduction to theoretical concepts, and it also provides detailed explanations, application examples, and case studies that deal with real-life problems. The chapter topics include questions that underlie critical thinking, interpretation, analytics, and making comparisons. Learning outcomes are defined and the content of the book is structured following these goals. Chapter 1 begins by introducing the basic concepts, methods, and processes of project management. This Chapter constitutes the base for defining and modeling project management problems. Chapter 2 explores the fundamentals of organizing and managing projects from an organization’s perspective. Issues related to project team formation, the role of project managers, and organization types are discussed. Chapter 3 is devoted to project planning and network modeling of projects, covering fundamental concepts such as project scope, Work Breakdown Structure (WBS), Organizational Breakdown Structure (OBS), Cost Breakdown Structure (CBS), project network modeling, activity duration, and cost estimating, activity-based costing (ABC), data and knowledge management. Chapter 4 introduces deterministic scheduling models, which can be used in constructing the time schedules. Models employing time-based and finance-based objectives are introduced. The CPM is covered. The unconstrained version of maximizing Net Present Value (NPV) is also treated here together with the case of time-dependent cash flows. Chapter 5 focuses on the time/cost trade-off problem, explaining how to reduce the duration of some of the activities and therefore reduce the project duration at the expense of additional costs. This topic is addressed for both continuous and discrete cases. Chapter 6 discusses models and methods of scheduling under uncertain activity durations. PERT is introduced for minimizing the expected project duration and extended to the PERT-Costing method for minimizing the expected project cost. Simulation is presented as another approach for dealing with the uncertainty in activity durations and costs. To demonstrate the use of the PERT, a case study on constructing an earthquake-resistant residential house is presented. Classifications of resource and schedule types are given in Chapter 7, and exact and heuristic solution procedures for the single- and multi-mode resource constrained project scheduling problem (RCPSP) are presented. The objective of maximizing NPV under resource constraints is addressed, and the capital-constrained project scheduling model is introduced. In Chapter 8, resource leveling, and further resource management problems are introduced. Total adjustment cost and resource availability cost problems are introduced. Various exact models are investigated. A heuristic solution procedure for the resource leveling problem is presented in detail. Also, resource portfolio management policies and the resource portfolio management problem are discussed. A case study on resource leveling dealing with the annual audit project of a major corporation is presented. Project contract types and payment schedules constitute the topics of Chapter 9. Contracts are legal documents reflecting the results of some form of client-contractor negotiations and sometimes of a bidding process, which deserve closer attention. Identification and allocation of risk in contracts, project control issues, disputes, and resolution management are further topics covered in this Chapter. A bidding model is presented to investigate client-contractor negotiations and the bidding process from different aspects. Chapter 10 focuses on processes and methods for project monitoring and control. Earned Value Management is studied to measure the project performance throughout the life of a project and to estimate the expected project time and cost based on the current status of the project. How to incorporate inflation into the analysis is presented. In Chapter 11, qualitative and quantitative techniques including decision trees, simulation, and software applications are introduced. Risk phases are defined and building a risk register is addressed. An example risk breakdown structure is presented. The design of risk management processes is introduced, and risk response planning strategies are discussed. At the end of the Chapter, the quantitative risk analysis is demonstrated at the hand of a team discussion case study. Chapter 12 covers several models and approaches dealing with various stochastic aspects of the decision environment. Stochastic models, generation of robust schedules, use of reactive and fuzzy approaches are presented. Sensitivity and scenario analysis are introduced. Also, simulation analysis, which is widely used to analyze the impacts of uncertainty on project goals, is presented. Chapter 13 addresses repetitive projects that involve the production or construction of similar units in batches such as railway cars or residential houses. Particularly in the construction industry repetitive projects represent a large portion of the work accomplished in this sector of the economy. A case study on the 50 km section of a motorway project is used for demonstrating the handling of repetitive project management. How best to select one or more of a set of candidate projects to maintain a project portfolio is an important problem for project-based organizations with limited resources. The project selection problem is inherently a multi-objective problem and is treated as such in Chapter 14. Several models and solution techniques are introduced. A multi-objective, multi-period project selection and scheduling model is presented. A case study that addresses a project portfolio selection and scheduling problem for the construction of a set of dams in a region is presented. Finally, Chapter 15 discusses three promising research areas in project management in detail: (i) Sustainability and Project Management, (ii) Project Management in the Era of Big Data, and (iii) the Fourth Industrial Revolution and the New Age Project Management. We elaborate on the importance of sustainability in project management practices, discuss how developments in data analytics might impact project life cycle management, and speculate how the infinite possibilities of the Fourth Industrial Revolution and the new technologies will transform project management practices.
The purpose of this manual is to familiarize industry and students with the technology of asphalt in its several forms namely asphalt cement, cutback asphalt, and asphalt emulsions. The laboratory work is designed to develop an understanding of asphalt properties, characteristics, testing procedures, and specifications. The procedures outlined are all derived from ASTM designations and practice as recommended by the Asphalt Institute. Where the particular ASTM method permits alternate procedures, the one more applicable to the available equipment and the teaching situation was chosen.The manual consists of the following:ò 35 of the frequently used ASTM tests in Asphalt Binder and Mix Design.ò Sample computations and easy to use data sheets, most of which have been developed specifically for the manual.ò An up-to-date overview of Asphalt Technology including sources, historical development, and classifications of asphalt products.ò Easy to understand explanations for Voids Mineral Aggregate, Absorbed Asphalt, Effective Asphalt Content, Percent Air Voids, and Percent of Voids filled with Asphalt.ò A stand-alone asphalt manual, written specifically for university laboratory instruction, yet applicable for a commercial testing laboratory. Rarely will other reference materials need to be referred to.ò Dimensions in both the SI and the US Standard systems of measurement.ò An appendix with conversion factors, rules of safety and procedures, overview of SHRP SUPERPAVE, explanation of asphalt emulsions, and additional data sheets on single-sided pages.
