Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 179-187).

Thesis (M.E.T.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. 110-111). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 156-162). Available also in a digital version from Dissertation Abstracts.

In this project the deformation behaviour of a rolled asphalt mixture is investigated, and the influence of temperature on the deformation mechanism of the mixture is assessed, based on a series of uniaxial creep and creep recovery experiments conducted under compressive stress and controlled temperature. Firstly, the experiments were conducted for various temperature levels, loading time, and number of load applications. It is found that the total strain consists of the elastic, plastic, viscoelastic and viscoplastic strain components. The temperature and number of load cycles hardly affects the elastic strain, but the plastic increases with temperature and decreases with number of load applications at constant stress levels. The timedependent (viscoelastic and viscoplastic) and the instant (elastic and plastic) deformation reduced respectively to viscoelastic and elastic deformation components at low temperature. Secondly the relationship between the total strain and the variables, time, temperature, stress and number of cycles are successfully modelled mathematically. After this, the model is introduced into the finite element method. Also an approximate approach for permanent deformation in a flexible pavement is presented and a non-linear finite element program "CEPVP" with consideration of the pavement temperature profile was devised. The calculation was conducted using program `CVEVP". It was found that there was a great agreement between the computation and the test. Finally, a general comparison of program 'CVEVP' and package ANSYS was conducted. Considering the effects of mechanical parameters of bituminous materials, time of loading, thickness of asphalt and granular layers and environmental temperature, calculation of permanent deformation of bituminous pavement was carried out using program `CVEVP'. Some findings were concluded. For example, it was found that the plastic properties of asphalt mixture are the important factor in calculating the permanent deformation of flexible pavements, particularly at the upper end of the temperature spectrum.

Thesis (M.S.)--Ohio University, March, 1997. / Title from PDF t.p.

The work presented in this thesis is aimed at improving the accuracy of one of the components of a flexible pavement design procedure commonly used in South Africa, namely the South African Mechanistic- Empirical Design Method. This is achieved through the development of a new design approach and permanent deformation model for the pavement subgrade. The new distress model for the pavement subgrade was developed from a comprehensive Accelerated Pavement Testing (APT) database on subgrade behaviour and permanent deformation that was generated by a fleet of Heavy Vehicle Simulators (HVSs) over 20 years of testing in South Africa. A literature review of the origin of the current subgrade design model that is used by the South African Mechanistic-Empirical Design Method revealed that that model is based on very little actual subgrade performance data. The model was also developed from the AASHO road test data and adjusted for South African conditions, based on general observations of subgrade behaviour without any calibration. Previous researchers have illustrated the potential of using Heavy Vehicle Simulator data to develop structural pavement design models and it was decided to apply a similar process to the permanent deformation of the pavement subgrade. The present investigation consisted of two components, namely, the evaluation of the resilient and the permanent deformation response of the pavement subgrade, the emphasis in this thesis being more on the permanent deformation response. A general, multi-dimensional empirical model was formulated for the permanent subgrade deformation and the characteristics of the model investigated based on previously published permanent deformation data and mathematical assessment. A set of 35 HVS tests for which suitable data were available was identified and additional field and laboratory tests were done on selected sites to improve the classification of the subgrade materials at these sites. Standard procedures were developed to present the pavement, instrumentation and load sequence data of each HVS test. A process for doing the initial analysis of the deflection and permanent MDD displacement data and presenting the data was also developed. In terms of the resilient response of the subgrade, it was shown that the vertical depth deflection and vertical strain could be modelled accurately if an appropriate set of resilient modulus values was selected for the pavement layers. A detailed investigation of the resilient response of selected HVS sections did, however, clearly illustrate the stress-dependent behaviour of subgrade material, resulting in resilient modulus values being determined, which were well outside the range that would normally be expected for natural gravel subgrade material. This research needs to be continued to enable the development of a comprehensive set of stress-dependent resilient modulus models for South African subgrade materials. The selection of an appropriate critical parameter that can be used as a predictor of permanent subgrade deformation was done by an investigation of the relationship between potential critical parameters and several permanent deformation parameters. It was found that the subgrade elastic deflection showed the best correlation with the subgrade bearing capacity (the number of load repetitions that can be sustained before a terminal rut condition is reached). The vertical subgrade strain that is currently used in the South African Mechanistic-Empirical Design Method in fact correlates poorly with subgrade bearing capacity and has to be replaced with subgrade elastic deflection. A set of subgrade bearing capacity or design models was developed for different levels of permanent subgrade deformation. These models are referred to as S-N models and form contour lines on the general permanent deformation model that was formulated. The subgrade design model accommodates loading conditions ranging from a 40 kN dual wheel load to a 100 kN dual wheel load as well as subgrade materials ranging from a material quality one class better than that which would normally be used for a subgrade, to the lowest possible material class. The model is therefore very flexible in terms of its application. / Prof. P. Pretorius

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2003. / Title from title page screen (viewed Sept. 26, 2003). Thesis advisor: Eric C. Drumm. Document formatted into pages (xx, 249 p. : ill. (some col.)). Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 216-229).

Thesis (M.S.)--Ohio University, June, 1995. / Title from PDF t.p.

Experimental and analytical investigations were performed to evaluate the comparative performance of pavements with and without geosynthetic stabilization. This was accomplished by the testing of a total of 18 pavement sections which could be classified into four different types: one which was constructed without geosynthetics and which served as a control, and three which were stabilized with one of two geotextiles or a geogrid. The pavement sections were constructed to model a typical secondary road in Virginia which is constructed over a silty sand subgrade material. Loading of the pavement sections was accomplished through the use of a computer-controlled pneumatic system which delivered 80 lb/in2 (552 kPa) through a rigid plate at a frequency of approximately one-half Hertz. The resulting displacement of the pavement surface was monitored by an array of linear variable displacement transducers (LVDTs). The performance of each pavement section was evaluated using the American Association of State Highway and Transportation Officials (AASHTO) flexible pavement design method. Models based on empirical and mechanistic relationships were considered. A theoretical pavement section was also analyzed to assess the influence of the stiffness of a wearing course layer. An economic study was performed to assess the potential cost benefit of geosynthetic stabilization and recommendations have been made for additional research. / Master of Science