THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

The global response to warming of 1.5oC comprises transitions in land and ecosystem, energy, urban and infrastructure, and industrial systems. The feasibility of mitigation and adaptation options, and the enabling conditions for strengthening and implementing the systemic changes, are assessed in this chapter.

Strengthening and Implementing the Global Response

100% recycled hot mix asphalt lab samples were modified with five generic and one proprietary rejuvenators at 12% dose and tested for binder and mixture properties. Waste Vegetable Oil, Waste Vegetable Grease, Organic Oil, Distilled Tall Oil, and Aromatic Extract reduced the Superpave performance grade (PG) from 94–12 of extracted binder to PG 64-22 while waste engine oil required higher dose. All products ensured excellent rutting resistance while providing longer fatigue life when compared to virgin mixtures and most lowered critical cracking temperature. Rejuvenated samples required more compaction energy compared to virgin and some oils reduced moisture resistance slightly.

Influence of Six Rejuvenators on the Performance Properties of Reclaimed Asphalt Pavement (RAP) Binder and 100% Recycled Asphalt Mixtures

A state-of-the-art review of parameters influencing measurement and modeling of skid resistance of asphalt pavements

Modelling the performance of asphalt concrete using continuum damage theories is an approach that has gained international attention in recent years. These types of models are advantageous because they ignore many of the complicated physical interactions at the microscale level and instead characterise a material using macroscale observations. One such model, the viscoelastic continuum damage model, is used in this study to examine the fatigue performance of asphalt concrete mixtures. A mathematically rigorous exploration is undertaken to specialise the model for easy prediction and characterisation using cyclic fatigue tests on cylindrical specimens. This process reveals that certain theoretical shortcomings are evident in other similar models and corrects them with a newly developed model. The resulting model is capable of capturing the underlying material property, i.e. the damage characteristic curve, which is responsible for the performance of controlled stress, controlled crosshead strain and consta...

Improved calculation method of damage parameter in viscoelastic continuum damage model

Transportation Resilience to Climate Change and Extreme Weather Events - Beyond Risk and Robustness

Fatigue performance modeling is a major topic in the field of asphalt concrete modeling work. Currently, the only standard fatigue test available for asphalt concrete mixtures is the flexural bending fatigue test, AASHTO T-321. Several issues are associated with flexural fatigue testing, the most important being that the stress state is not uniform but varies with the depth of the specimen, and that the beam specimen fabrication equipment is not widely available. Viscoelastic continuum damage (VECD) fatigue testing is a promising alternative to flexural fatigue testing. Different researchers have successfully applied the VECD model to asphalt concrete mixtures using constant crosshead rate direct tension tests. However, due to the load level limitation of the newly released Asphalt Mixture Performance Tester (AMPT) testing equipment, there is an immediate need to develop a model that can characterize fatigue performance quickly using cyclic test data. In this study, a simplified VECD model, developed at North Carolina State University, is applied to various North Carolina mixtures that are part of the NCDOT project, Local Calibration of the MEPDG for Flexible Pavement Design. A failure criterion that is based on pseudo stiffness is developed from the test data. The application of the VECD model using this failure criterion results in very good agreement between the measured and predicted fatigue life for the eleven mixtures. In addition, a completely independent verification study is conducted for the FHWA ALF mixtures, including both unmodified and modified mixtures. Again, it is found that the simplified VECD model predicts the fatigue life of the ALF mixtures well. It is shown that the simplified VECD model based on the data from a single temperature and a single strain level can predict fatigue test results fairly accurately under various temperature conditions and at various strain levels. It is also shown that the model can be utilized further to simulate both controlled strain and controlled stress direct tension fatigue testing and gain insight into the impact of various mixture design variables, such as asphalt content, binder grade, NMAS, and the inclusion of RAP materials, on the fatigue performance.

Fatigue Performance Prediction of North Carolina Mixtures Using the Simplified Viscoelastic Continuum Damage Model

Healing characteristics of asphalt binder

The selection of materials for road construction in the United States is based on assumptions of a stationary climate. With increasing temperatures, upholding these practices could add up to US$26.3 billion in US-wide maintenance costs by 2040 under RCP8.5. Roadway design aims to maximize functionality, safety, and longevity1,2. The materials used for construction, however, are often selected on the assumption of a stationary climate1,3. Anthropogenic climate change may therefore result in rapid infrastructure failure and, consequently, increased maintenance costs, particularly for paved roads where temperature is a key determinant for material selection. Here, we examine the economic costs of projected temperature changes on asphalt roads across the contiguous United States using an ensemble of 19 global climate models forced with RCP 4.5 and 8.5 scenarios. Over the past 20 years, stationary assumptions have resulted in incorrect material selection for 35% of 799 observed locations. With warming temperatures, maintaining the standard practice for material selection is estimated to add approximately US$13.6, US$19.0 and US$21.8 billion to pavement costs by 2010, 2040 and 2070 under RCP4.5, respectively, increasing to US$14.5, US$26.3 and US$35.8 for RCP8.5. These costs will disproportionately affect local municipalities that have fewer resources to mitigate impacts. Failing to update engineering standards of practice in light of climate change therefore significantly threatens pavement infrastructure in the United States.

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B. Shane Underwood

Papers

Improved calculation method of damage parameter in viscoelastic continuum damage model

Transportation Resilience to Climate Change and Extreme Weather Events - Beyond Risk and Robustness

Fatigue Performance Prediction of North Carolina Mixtures Using the Simplified Viscoelastic Continuum Damage Model

Healing characteristics of asphalt binder

Increased costs to US pavement infrastructure from future temperature rise