This study involved the determination of the structural layer properties of aggregate and asphalt surfaced pavements for use in the evaluation of pavement load carrying capacity and the seasonal effects of moisture. This was achieved by the use of Nondestructive Testing Methods (NDT) and backcalculation techniques. Pavement surface deflection measurements were taken using three NDT devices, namely the Dynaflect, Road Raterand Falling Weight Deflectometer (FWD). Soil moisture cells were implanted in the subgrade to monitor the moisture content and temperature of the subgrade. Samples of the pavement materials and subgrade were taken for evaluation in the laboratory using standard methods. A total of 27 project sites were studied. The deflection data collected using NDT devices were used to backcalculate pavement layers and subgrade moduli. The backcalculation procedures used were BISDEF, MODCOMP2, and SEARCH. The backcalculated moduli obtained from different equipment for any test site were compared to each other. Also, the backcalculated moduli were compared to laboratory determined values. Attempts were made to develop regression equations relating subgrade moisture content to easy-to-measure variables, such as rainfall, site aspect, pavement thickness and elevation. Also, for a known stress state, attempts were made to develop a regression equation which can be used to predict modulus as a function of dry density and moisture content. Finally, a regression equation was developed for the prediction of backcalculated modulus from pavement surface deflection basin for aggregate surfaced roads. The results from the study show that backcalculation methods can be used to determine the moduli of aggregate and asphalt surfaced pavement layers. These methods are limited in that they cannot take into account the stress sensitivity of the pavement materials and subgrade. As such, the backcalculated modulus denotes the relative stiffness of the pavement layer and cannot be compared to the modulus obtained in the laboratory at a specific loading situation. Nevertheless, it was shown that the backcalculated modulus changes with the moisture content and, therefore, can be used to evaluate the seasonal effects of moisture. The results can be used in the management of low volume roads, first by providing a means of evaluating the in situ pavement conditions at any given time. This can be used to develop rational load restriction policies during the critical season of the year. The backcalculated moduli can also provide a reliable input in overlay and reconstruction design. Finally, the prediction equations can provide an easy method for obtaining the resilient modulus for input into a mechanistic design method.

Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.

The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.

Seven flexible pavements ranging from interstate to state route are selected. Three different approaches are employed. The first two use the resilient modulus of the material to estimate its structural coefficient. In the first approach, cored specimens are obtained from each of the pavement sections and the resilient moduli of in-service 301 and 446/448 materials are determined in the laboratory. The second approach backcalculates layer elastic modulus from measured pavement deflection. The third approach determines the structural coefficient from the AASHTO flexible pavement performance equation based on traffic and serviceability history data.

Structural Behavior of Asphalt Pavements provides engineers and researchers with a detailed guide to the structural behavioral dynamics of asphalt pavement including: pavement temperature distribution, mechanistic response of pavement structure under the application of heavy vehicles, distress mechanism of pavement, and pavement deterioration performance and dynamic equations. An authoritative guide for understanding the key mechanisms for creating longer lasting pavements, Structural Behavior of Asphalt Pavements describes the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performances, and demonstrates the process of pavement analyses and designs, approaching science from empirical analyses. Analyzes the external and internal factors influencing pavement temperature field, and provide a review of existing pavement temperature prediction models Introduces a “Bridge Principle through which pavement performance and fatigue properties are consolidated Defines the intrinsic consistency between macroscopic performance and microscopic response, structure and material, as well as global and local performance Summaries the mechanistic response of pavement structure under the application of heavy vehicle, distress mechanism of pavement, pavement deterioration performance and dynamic equations, and life cycle analysis of pavement

Asphalt Surfacings has been written as a reference to the various asphalt course materials and surfacing treatments that are currently available to engineers, enabling them to select the materials and/or treatment that are appropriate for use on specific sites. Appropriate reference is made to the lower structural layers as the properties of all layers interact in producing the required pavement. The current established position in the UK and the emerging developments throughout the UK and Europe are covered. The contributors are all acknowledged authorities on their particular topics selected from every part of the highway engineering industry to achieve a balance between the various approaches required by the different functions they perform.