(1991). Applied Linear Regression Models. Journal of Quality Technology: Vol. 23, No. 1, pp. 76-77.

Applied Linear Regression Models

Polymer modified asphalt binders

The fifth edition of "Numerical Methods for Engineers" continues its tradition of excellence. Instructors love this text because it is a comprehensive text that is easy to teach from. Students love it because it is written for them--with great pedagogy and clear explanations and examples throughout. The text features a broad array of applications, including all engineering disciplines. The revision retains the successful pedagogy of the prior editions. Chapra and Canale's unique approach opens each part of the text with sections called Motivation, Mathematical Background, and Orientation, preparing the student for what is to come in a motivating and engaging manner. Each part closes with an Epilogue containing sections called Trade-Offs, Important Relationships and Formulas, and Advanced Methods and Additional References. Much more than a summary, the Epilogue deepens understanding of what has been learned and provides a peek into more advanced methods. Approximately 80% of the end-of-chapter problems are revised or new to this edition. The expanded breadth of engineering disciplines covered is especially evident in the problems, which now cover such areas as biotechnology and biomedical engineering. Users will find use of software packages, specifically MATLAB and Excel with VBA. This includes material on developing MATLAB m-files and VBA macros.

Numerical methods for engineers

Introduction to physical polymer science

Recycling of waste tire rubber in asphalt and portland cement concrete: An overview

This paper presents the formulation and the application of a continuum-based finite-layer approach to evaluate pavement strain response under actual traffic loading. The model incorporates important pavement response parameters such as the dynamic tire-pavement load variations and corresponding complex contact stress distributions (normal and shear), vehicle speed, and viscoelastic material characterization. Results of a parametric study in which two typical thin and thick pavement sections were subjected to traffic loading moving at different speeds are included. As an important application of the proposed method, pavement strain responses generated by wide-base and dual tires have been presented. This study reveals that contradictory to the past studies, the impact of tire-pavement contact shear stress on tensile strain at the bottom of asphalt concrete is insignificant.

Pavement Strain from Moving Dynamic 3D Load Distribution

This paper documents many important pavement response parameters generated from the finite-layer analytical model, 3D-Moving Load Analysis, under a variety of loading conditions. The loading conditions reported include two types of tires (conventional and wide base) and different contact stress distributions (uniform and nonuniform). The data generated from this study reveal that there is a significant difference between the responses computed with uniform (conventional assumption) and nonuniform contact tire-pavement stress distributions. This difference varies between 6 and 30%, depending on the loading conditions. Except in the case of tensile strain at the bottom of the asphalt concrete layer, the responses computed with the nonuniform stress distribution are lower. This indicates that the use of conventional load distributions is conservative, at least in the case of the estimation of pavement rutting. Vehicle speed showed significant impact on all pavement response parameters, and its influence was consistent with those measured in many field tests. The database of pavement responses presented in the study can be used to compare the performance of pavements under a variety of conditions—for example, thin versus thick pavements, wide-base versus conventional tires, slow versus high speed of the vehicle, and so on. Furthermore, the study reveals that the inclusion of contact shear stresses (longitudinal and transverse) did not significantly influence any of the important pavement response parameters.

Investigation of Tire Contact Stress Distributions on Pavement Response

This report presents recommended changes to American Association of State Highway and Transportation Officials (AASHTO) Standard Method of Test T283, "Resistance of Compacted Bituminous Mixture to Moisture Induced Damage," to enhance T283's compatibility with Superpave volumetric mix design. It will be of particular interest to materials engineers in state highway agencies and contractor personnel responsible for the design of hot-mix asphalt (HMA) according to the current Superpave or older Marshall and Hveem methods. Moisture damage in HMA pavements gained national attention in the late 1970s, and its reported occurrence continues to grow. Moisture damage contributes to a variety of distresses that significantly diminish the performance and service life of HMA pavements.

Compatibility of a Test for Moisture-Induced Damage with Superpave Volumetric Mix Design

An interlaboratory study was conducted to develop a precision statement for ASTM D 5821-95, Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate. The experimental design included ten laboratories, four materials, and three replicates per material per laboratory, resulting in 54 degrees of freedom. Outlier detection was given careful con sideration due to the subjective nature of the method, and resulted in exclusion of one laboratory's data, reducing the degrees of freedom to 48. The materials included three partially crushed gravel blends and one quarry stone blend. As expected, multilaboratory variability was greater than singleoperator variability. There was also a greater level of variability associated with two or more fractured face determinations than with one or more fractured face determinations. Surprisingly, the greatest variability was observed for the quarry stone rather than for the crushed gravels. The results of the analysis were compared with other available data. The level of variability associated with this study was less than that observed in other studies, due most likely to the highly fractured nature of the materials used in the study.

Precision of ASTM D 5821 standard test method for determining the percentage of fractured particles in coarse aggregate

This paper presents the findings of a laboratory-based research project that evaluated the impact of three RAP sources at three levels of RAP content (0, 15, and 30%) on the mechanical properties of the final mix. Two asphalt binder grades were targeted for the final mix. The binder grade for the new asphalt binder was selected using appropriate blending charts for high and low temperatures. Overall the addition of RAP to a mixture resulted in an acceptable moisture resistance, however a reduction in the unconditioned and conditioned tensile strength was observed. In most of the cases, the addition of RAP to a mixture resulted in an equivalent or better rutting resistance than the virgin mix (0% RAP). Depending on the RAP source and content, the addition of RAP to a mixture with an unmodified target asphalt binder resulted in either a better or worse fatigue resistance. On the other hand the addition of RAP to a mixture with a polymer modified target asphalt binder resulted in a worse fatigue res...

Peter E. Sebaaly

Papers

Pavement Strain from Moving Dynamic 3D Load Distribution

Investigation of Tire Contact Stress Distributions on Pavement Response

Compatibility of a Test for Moisture-Induced Damage with Superpave Volumetric Mix Design

Precision of ASTM D 5821 standard test method for determining the percentage of fractured particles in coarse aggregate

Laboratory Evaluation of Mixes Containing Recycled Asphalt Pavement (RAP)