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.

vii, 280 p. A print copy of this title is available through the UO Libraries under the call number: SCA Archiv Theses H855 / Adviser: Earl Pomeroy

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.

Moisture damage is one of the major causes of premature failure of road pavements especially the pavements made using the flexible design concept. This failure occurs as a result of cohesion and adhesion loss between the binder and binder-aggregate interfaces respectively. One of the many ways of mitigating moisture damage effect is the use of anti-stripping agents like liquid polymers, Portland cement, hydrated lime, fly ash, flue dust, etc. Hydrated lime has been found to be one of the most efficient anti-stripping agents among all common additives to asphalt mixtures. Although the majority of research on the use of hydrated lime in asphalt mixtures has been carried out in the USA, the beneficial effects of hydrated lime have also been reported worldwide especially in Europe. In the UK, the use of hydrated lime only started in the early 2000’s and still needs a lot of research in terms of selection of aggregates which can be improved with the use of hydrated lime. Most of the aggregates used in the UK for asphalt mixtures are of good field performance and it is difficult to find aggregates with poor quality. That is the reason why for this research four aggregate types which are commonly used in the UK for flexible road payments are selected. One type of bitumen having penetration grade of 40/60 has been selected for the research. The four aggregate types include granite, limestone, basalt and greywacke. This research focuses on an in-depth investigation of hydrated lime performance against moisture damage in bitumen mastics and asphalts mixtures as a whole. The full project has been broken down into three parts. The first part is a component level study, the second is mixture level study and the third is the study of practical adhesion. In the component level study, the effect of hydrated lime is quantified in terms of adhesion properties between a range of aggregates and binder combinations. For the component level testing, the effect of hydrated lime is quantified by adding it to the bitumen to make a mastic. The test techniques which are used for the component level assessment includes rolling bottle test and surface energy measurement. The second part focuses on the performance of hydrated lime as a whole inside asphalt mixture as filler replacement. The idea behind this methodology is to evaluate the real effect of hydrated lime in the mixture because if hydrated lime is used as additional filler in the mixture it will alter the mixture volumetric rather than simply affecting the mechanical response of the mixture through the properties of the hydrated lime. SATS test has been used to quantify the effect of hydrated lime against moisture damage at mixture level. The third part of the research deals with the measurement of practical adhesion with and without moisture conditioning with the help of pull-off and peel-off test techniques called PATTI and Peel test. The effect of hydrated lime either in the mastic or in the mixture has been found to be aggregate type dependent. Granite aggregates showed a good improvement in the performance against moisture damage resistance with the use of hydrated lime. Limestone aggregate didn’t respond to the addition of hydrated lime in the light of most of the techniques considered in this research and the same applied to the basalt aggregates. Greywacke, on the other hand, responded well and showed an improved moisture damage performance with the use of hydrated lime. Another good thing observed in the results was the consistency between the results among the different test techniques. The results obtained in each technique are in line with each other and give the same conclusion for most of the combinations studied in this research. To conclude, the effect of hydrated lime highly depends on the type of aggregate, its origin and its mineral composition. The aggregates used in this study were either of moderate or good field performance. Although a good improvement in the moisture damage performance of some combinations was clearly observed, it is highly recommended to incorporate the aggregates having bad field performance to see how hydrated lime improves their performance. Keywords: Moisture Damage, Hydrated lime, Surface Energy, Adhesion, Asphalt Mixture, Rolling Bottles Test (RBT), Saturation Ageing Tensile Stiffness (SATS) Test, PATTI test, Peel test.

Service life of asphalt roads could be extended by enhancing the natural self-healing ability of asphalt mixtures with encapsulated rejuvenators. When crack damage appears, the capsules release healing agents, which dissolve bitumen to flow into cracks. In this research, a new type of capsules was developed. These capsules contain sunflower oil as a rejuvenating agent. The size, morphology, mechanical strength and thermal stability of these capsules were investigated. The composition of the capsules, which nominally divides these capsules into different types based on their oil content, epoxy-cement shell and polymer amount, and its effect on capsule characteristics were also studied. In addition, the effect of the capsules on the chemical composition of bitumen with time of exposure to broken capsules was evaluated by the FTIR test. Results show that the characteristics of the capsules and their effect on chemical composition allow them to be incorporated in asphalt mixtures for further investigations for their effect on asphalt mechanical performance and self-healing. The mechanical performance of aged asphalt mixtures is investigated by using three nominally different types of capsules. Two of these were protected with a hard shell made of epoxy-cement composite; two coats with 1.0 o/w (oil-to-water), three coats with 1.0 o/w and without the hard shell with 0.5 o/w. The optimum amount of capsules used in all mixtures was 0.5% of total mass of asphalt mixture. Tests started by investigating the effect of mixing and compaction processes on these capsules. Results show that the hard shell (epoxy-cement) was not necessary for the capsules to survive mixing and compaction processes. Capsules deformed and broke with cyclic loading, releasing oil that diffused in the bitumen in less than 24h. Healing of cracks in aged asphalt mixtures led to an increase of stiffness under cyclic loading. However, asphalt specimens with capsules had lower deformation resistance. Computer tomography scanning of specimens showed large reductions in cracks around the capsules, after resting 4 days (96h) at 20oC. The mechanical properties of asphalt mixture containing capsules have been evaluated. Including water sensitivity, particle loss, stiffness and permanent deformation. One type of capsule (0.1 o/w) with three different capsule contents by mass of asphalt mixture were used, 0.1%, 0.25% and 0.5% with oil-to-bitumen ratio 1.1, 2.8 and 5.5, respectively. Capsules were strongly bonded to the asphalt mixture and results showed improved or at least similar mechanical properties to that of asphalt mixtures without capsules. This shows that capsules for asphalt self-healing can be safely used in the road, without affecting its quality. Asphalt containing capsules had slightly lower stiffness (no rest period), which can be easily solved by reducing the size of the capsules in the future. Furthermore, a new method for testing asphalt self-healing by the action of capsules was designed and tested. This method was based on a 3-point bending test (3PB) to beak samples and measure their flexural strength. The test was implemented by comparing the strength recovery of the broken beams after healing to their original flexural strength. The test was first applied to asphalt mastic beams, which are asphalt mixtures with higher bitumen content and fine aggregate and filler. Five different types of capsules used, based on their o/w ratios. These were 0.05, 0.1, 0.2, 0.5 and 1.0 o/w ratios with different amounts depending on their oil content so that they can provide a 7.2% of rejuvenator (sunflower oil) to the asphalt mastic beams. The effect of capsule content on self-healing was investigated by the 3PB on samples containing all those five capsule types (different contents) at one healing temperature, namely 20oC and different healing times. Effect of temperature on healing was investigated as well by 3PB test applied to mastic beams containing one type of capsules with 0.5 o/w ratio at four different temperatures, namely 5oC, 10oC, 15oC and 20oC. The main results showed that the capsules can break inside the asphalt mastic releasing the encapsulated oil to bitumen. Healing levels in the asphalt mastic samples with capsules were greater than samples without capsules, and the healing level of asphalt samples with, and without, capsules increased with the healing time. Additionally, the healing level given by the capsules inside the cracked asphalt mastic depended on the oil/water content of the capsule and on the temperature at which the healing process occurs. Finally, a correlation factor was developed between the healing level of asphalt mastic with and without capsules, independent of the temperature and time evaluated. Self-healing of real asphalt mixture was also investigated by same method of 3PB at different healing times and different temperatures. One type of capsules, namely 0.1 o/w with three different capsule contents, 0.10%, 0.25% and 0.50% by total weight of the mixture, were mixed with the asphalt. Eight different healing temperatures were used in this test, namely -5oC, 5oC, 10oC, 15oC, 20oC, 30oC, 40oC and 50oC. It was proven that the capsules can resist the mixing and compaction processes and break inside the asphalt mixture as a result of applying external mechanical loads, releasing the encapsulated oil. The capsules content in asphalt mixture has a significant influence on the healing level, where a higher capsule content led to higher healing levels. It was found that cracked asphalt mixture with capsules recovered 52.9% of initial strength at 20oC versus 14.0% of asphalt mixture without capsules. Likewise, asphalt with, and without, capsules presents an increase of the healing level when the temperature increases. Finally, it was proved that healing temperature over 40oC has significant influence on the healing levels of the asphalt beams.

Several benefits are gained from using cold mix asphalt (CMA) instead of hot mix asphalt (HMA). The benefits include conservation of materials and reducing energy consumption, preservation of the environment and reduction in cost. One of the common types of CMA is cold bitumen emulsion mixture (CBEM) which is the mixture produced by mixing mineral aggregate with bitumen emulsion. Despite the efforts applied in the last few decades in order to improve and develop CBEM utilization, certain deficiencies remain that make it inferior to HMA, resulting in restricting or minimizing of its use. However, the development of CBEM for road construction, rehabilitation and maintenance is steadily gaining interest in both pavement engineering industrial and research sectors. The present study was primarily aimed at evaluating the effect of using different cementitious materials on the performance of CBEM. The idea of the research is to provide a sustainable filler from supplementary cementitious materials (SCMs) to be used as fillers to provide enhanced properties of CBEMs. By achieving this aim it is expected that the utilization of CBEM would increase, allowing them to be used as structural pavement materials with some confidence. Research was first undertaken to optimize the mix design of CBEM using a statistical approach known as response surface methodology (RSM), as an alternative approach to achieve acceptable engineering properties. The optimization of CBEM was investigated, to determine optimum proportions to gain suitable levels of both mechanical and volumetric properties. This optimization focussed on the mix design parameters, namely bitumen emulsion content (BEC), pre-wetting water content (PWC) and curing temperature (CT). This work also aimed to investigate the effect of the interaction between these parameters on the mechanical and volumetric properties of CBEMs. The results indicate that the interaction of BEC, PWC and CT influences the mechanical properties of CBEM. However, PWC tends to influence the volumetric properties more significantly than BEC. The individual effects of BEC and PWC are important, rather than simply the TFC which is used in conventional mix design of CBEM. Furthermore, the experimental results for the optimum mix design corresponded well with model predictions. It was concluded that optimization using RSM is an effective approach for mix design of CBEMs. The study also investigated in-depth the performance characteristics of CBEMs using different filler treatments. The study was extended to understand the performance enhancement through mineralogical and microstructural investigations. The research was designed to use cement, binary and ternary blended fillers (BBF and TBF). Fly ash (FA) and ground granulated blast-furnace slag (GGBS) were used as BBF while silica fume (SF) was added to the BBF to obtain TBF. A significant improvement was achieved in mechanical and durability properties of CBEMs due to incorporation of both cement and blended fillers. Also, the results indicated that TBF was more suitable than BBF for the production of CBEMs. The microstructural assessment indicated that the effect of BBF on the internal microstructure of CBEMs was slightly negative and more noticeable in CBEMs containing FA. Mineralogical and microstructural assessments also suggested that the presence of bitumen emulsion might not affect the hydration of the silicates in treated CBEMs. The formation of additional CSH was observed due to the replacement of conventional limestone filler by cement, BBF and TBF. However, it seems that this can cause a delay in the formation of other hydration products (Ettringite) resulting from the hydration of aluminates in cement. Furthermore, it is proposed that the addition of SF to BBF mixtures can eliminate the delay in formation of hydration products caused by the bitumen emulsion. The present work was also aimed at better understanding the curing mechanism of CBEMs and to bridge the gap between laboratory curing and field evolution of these mixtures. This was achieved by evaluating the effect of the curing process on CBEM performance and developing a prediction model to assess in-situ CBEM performance using maturity relationships. Different contributory factors affecting the curing process were investigated such as curing temperature and relative humidity (RH) in addition to the impact of curing time and the presence of cement/active fillers. The results indicated that high curing temperature is responsible for additional stiffness gain by increasing the binder stiffness due to ageing and by increasing the moisture loss by evaporation during the curing process. However, at high curing temperature the moisture loss by evaporation may hinder the hydration of cement/active fillers. Moreover, the results also indicated that the high RH level influences the stiffness modulus of CBEMs negatively. The laboratory results were then used to develop a tool to assess in-situ curing of CBEMs using the maturity approach, which is widely used to estimate in-situ concrete properties. A strong correlation was found between maturity and the stiffness values obtained from the laboratory tests, which resulted in development of maturity-stiffness relationship. The application of this relationship to assess the in-situ stiffness of CBEMs is presented using three hypothetical pavement sections in the United Kingdom, Italy and Qatar; to simulate different curing regimes. A pavement analysis and design study was conducted to evaluate the incorporation of treated CBEMs into a pavement structure. CBEMs are suggested to be used in two scenarios: the first is as a surface course and the second is as a base course. The scope of the study is limited here to design based on the fatigue criterion only. Although, the structural design was based on practical hypothetical layer thicknesses, the results provided useful insight into the structural capabilities of CBEMs.

Aubrey Berrangé, a South African roads engineer, invented the impact compactor in 1949 with the intention of achieving improved compaction to greater depths than possible with conventional equipment available at the time. The aim of this dissertation is to present a simple prediction model for the profile of improvement in the ground, using surface settlement as the main input parameter. The model is based on the information reviewed, observation of field data and a static numerical analysis. For simplicity sake, no attempt is made to predict the energy requirement to achieve the input value of settlement. The model is then verified on fifteen impact compaction profiles at six different sites. A 2 ton-meter dropping mass compactor was also used in the verification process with reasonable success. In addition, the model was tested against comprehensive testing performed at a dynamic compaction site with very promising results. The method is also shown to give acceptable results for prediction of density increase during a vibratory compaction trial. It is concluded that the improvement in the ground can be estimated with reasonable success if the surface settlement is monitored, providing strains are taken into account. / Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2006. / Civil Engineering / unrestricted

In the increasingly urban context of North America, urban transportation poses increasingly complex problems. Not the least of these is the problem of financing highway systems that are considered essential to the smooth and expeditious flow of goods and people within the cities. One difficulty arises out of the fragmented political jurisdictions that exist within the boundaries of most urban areas today. After agreement has been reached on the contribution, if any, by senior levels of government towards any major highway improvement in an urban area, the remaining cost has still to be allocated amongst the member municipalities in the area. Every municipal council is thus faced with the problem of assuming an additional cost for municipal services, i.e. for providing adequate, improved highway facilities. But current methods of allocating these costs do not clearly relate them to the benefits received by those who live and work in the municipality. Nor do they relate them to any discernible social policy. The main hypothesis of this paper is that it is possible to develop a formula that does relate the costs chargeable to any municipality to the benefits received by those who live and work in that municipality. This cost-sharing formula has been developed in this study. The basic assumptions on which its claim to equity is made are given . The social policies that could be considered are spelled out, and their justification for modifying the cost figures derived is examined. Practical recommendations for the use of this procedure are made, and the planning implications involved are considered. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

Oil boom in Western North Dakota State brings increasing number of oil trucks. The distinct characteristics of heavy vehicles such as oil trucks: low speed, large size, and slow accelerate and decelerate results in inaccuracy in traffic capacity forecasting and safety analysis. In this research, to calculate passenger car equivalent (PCE) factor of heavy vehicles, such as oil trucks, on two-lane rural highway, an improved analytical method based on headway and delay is introduced. It considers several elements that have effect on PCE factor: vehicle speed, safety passing time, headway distribution, level of service (LOS), and delay to downstream traffic. The new set of PCE factor values are classified into three groups corresponding to different LOS.