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.

With maintenance costs accounting for a large proportion of road budgets, this report assesses the economic and technical feasibility of innovative wearing courses for long life road pavements. While having higher initial costs, such wearing courses ...

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.

Asphalt Pavements provides the know-how behind the design, production and maintenance of asphalt pavements and parking lots. Incorporating the latest technology, this book is the first to focus primarily on the design, production and maintenance of low-volume roads and parking areas. Special attention is given to determining the traffic capacity, required thickness and asphalt mixture type for parking applications. Topics covered include: material information such as binder properties, testing grading and selection; construction information such as mixing plant operation, proportioning, mixture placement and compaction; and design information such as thickness and mixture design methods and guidelines on applying these to highways, city streets and parking Areas. It is an essential practical guide aimed at those engineers and architects who are not directly involved in the asphalt industry, but who nonetheless need to have a good general knowledge of the subject. Asphalt Pavements provides a novice with enough information to completely design, construct and specify an asphalt pavement.

Pavements are omnipresent in our society. From roads and airports to parking lots and driveways, every civil engineering project requires applications of this complex subject. Pavement Engineering covers the entire range of pavement construction, from soil preparation to structural design and life-cycle costing and analysis. It links the concepts of mix and structural design, while also placing emphasis on pavement evaluation and rehabilitation techniques. State-of-the-art content introduces the latest concepts and techniques, including ground-penetrating radar and seismic testing. The text facilitates a general course for upper-level undergraduates, covering the selection of materials, mix and structural design, and construction. It also provides laboratory and field tests accompanied by a discussion of new and advanced concepts. This unique text prepares the next-generation of engineers with the core principles and application knowledge needed to maneuver in the ever-expanding pavement engineering industry.