Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 78 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 69-71).

Thesis (M.S.)--Rowan University, 2008. / Typescript. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Rowan University, 2005. / Typescript. Includes bibliographical references.

Thesis (MCE)--University of Delaware, 2005. / Principal faculty adviser: Nii O. Attoh-Okine , Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (MIng)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

No description available.

Most pavements around the world are built with asphalt mixtures. Traditional asphalt mixtures are composed of aggregates and bitumen. Current concern about environmental issues and scarcity of these raw materials has motivated the search for different recycled and renewable resources to be used in pavement engineering. Regarding recycling, the use of Reclaimed Asphalt (RA) materials is nowadays a common and valued practice. However, there still exist some concern about its performance when used in high amounts (>30%) due to its aged state. In terms of renewable resources, the relatively new concept of biobinders (binders manufactured from biomass), as suitable asphalt binder alternatives, is gaining force in pavement engineering. To date, biobinders have shown great potential not only to reduce bitumen demand, but also exhibiting good performance in terms of resisting the main distresses affecting pavements. However, biobinders need in-depth and detailed characterisation in terms of engineering properties before they can be used in practice. The combination of RA and biobinders can be considered as an innovative technique to reduce the consumption of aggregates and bitumen. Within this framework, the main aim of the research described in this thesis was to study the performance of RA mixtures with biobinders at binder and mixture scale in order to gain further understanding of their suitability to be used in actual pavements. For this purpose, biobinders manufactured from pine resin, linseed oil and by-products of the paper industry have been investigated as binders for the total replacement of the virgin bitumen needed in high RA content asphalt mixtures. The research initially focused on the design of the blend of RA binder and biobinders through the study of their conventional and rheological properties which were subsequently used as an input in the design of the asphalt mixtures. Once the design parameters were fixed, the blends of RA binder and biobinders were characterised in terms of their rheological, ageing and adhesion properties, and their performance tested in terms of study rutting, fatigue and thermal cracking resistance. Then, 50% RA mixtures and 70% RA mixtures were characterised for the same properties and the relationships between binder blends and asphalt mixtures were studied. The results showed that the biobinders studied are viscoelastic materials able to efficiently restore some of the properties of the RA binder in an equivalent or better way than conventional bitumens, increasing its viscous component and decreasing its stiffness. The mechanical performance of biobinders and bio-asphalt mixtures regarding rutting, fatigue, thermal cracking and moisture damage was found to be comparable to conventional mixtures. Good relationships were found between the binder blends and asphalt mixtures performance under the assumption of full blending, even though the exact degree of blending remained unknown. In this regard, the blend design performed as the first step was found to satisfactorily work as the input for the design of high RA content asphalt mixtures. Biobinders and bio-asphalt mixtures showed the same ageing tendency as conventional materials although ageing occurred at a faster rate, which can be considered the main drawback of their performance. In the light of the results obtained in this thesis for the materials studied, high RA content asphalt mixtures with biobinders can be considered promising materials to be used in pavement engineering. Full-scale experiments could be the final step for their development.

Harvesting Energy stands as one of the most promising techniques for approaching the global energy problem without depleting natural resources. Pavement solar energy harvesting (PSEH) technology is one of these techniques and it is considered as a new research area and currently under development which aims to enhance pavements for capture, and storage of thermal energy. To advance the study of PSEH, a study was made of the influence of moisture inside asphalt on its energy transport and storage abilities. Measurements of almost all the key thermal properties of asphalt are reported for a range of mixtures with various air void contents ranging from 4.5% to 30%. On the basis of this study it is concluded that, under dry conditions, asphalt mixtures with low air voids content have higher thermo-physical properties (i.e. density, thermal conductivity, specific heat capacity, thermal diffusivity and thermal effusivity) than asphalt mixtures with higher air voids content. Therefore, heating and cooling rates of dense asphalt mixtures were higher than those from porous asphalt mixtures. The total amount of energy accumulated in asphalt mixtures with different air voids content, but with the same constitutive materials, during heating and cooling depends only on the density of the mixtures. In addition, results indicate that asphalt mixtures with high air voids content accumulate less energy than asphalt mixtures with lower air voids content. It is concluded that mixtures with high air voids content are recommended to alleviate the urban heat island effect while mixtures with low air voids content are recommended for harvesting solar heat from pavements. It is concluded that under wet conditions, a relationship exists between the evaporation rate, the heat flux, and the surface temperature during water evaporation. In addition, the evaporation rate has been related to air voids parameters such as air voids content and diameter, tortuosity, or the Euler number. The study also investigated the feasibility of harvesting heat from asphalt concrete mixtures by Thermoelectric Power Generators (TEG) and how the air voids content can affect the recovery of this heat. It was found that increasing and/or maintaining the temperature difference between the hot side and cold side of a TEG is considered to be the most important factor in energy recovery application from asphalt pavement. It is concluded that maintaining the temperature gradient between the asphalt pavement and the subgrade could provide a potential of converting heat energy to electrical energy through the use of Thermoelectric Power generators.

Prediction of pavement performance is important to pavement engineers. Pavement surface deterioration is a dynamic and complicated process. Moisture damage and fatigue are considered as two major causes of pavement deterioration. During a pavement’s service life, the presence of water can lead to loss of stiffness and strength of the asphalt pavement structure. Apart from that, the presence of water can accelerate the propagation and severity of already existing distress. High tensile strain at the bottom of an asphalt layer results fatigue cracking in a pavement. The goal of this research was to develop a series of computational models to predict pavement surface deterioration under the effects of moisture and traffic. The first task was to calculate the pavement surface water pressure under a moving tyre. The water is compressed underneath the tyres, generating a water pressure pulse. This pressure allows surface water to penetrate into the pavement structure. Then the asphalt pavement internal structure (voids distribution) was determined and the water pressure distribution inside the pavement structure was calculated for both fully saturated and partially saturated condition using the surface water pressure. The water pressure expands the voids inside the pavement. Consequently, stress and strain at the edge of the voids, due to frequent traffic passes can lead to failure of the pavement. A ravelling failure probability line was then predicted with the help of cavity expansion theory and asphalt crack propagation law. The case study for the performance of four different asphalt types (HRA, SMA, AC, DBM) using the failure probability calculation shows a good correspondence with their real performance which indicates that this process of predicting failure probability is generally acceptable.