Thesis (M.S.)--University of Nevada, Reno, 2008. / "May, 2008." Includes bibliographical references (leaves 155-160). Online version available on the World Wide Web.

Orientador: João Virgilio Merighi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-12T06:59:48Z (GMT). No. of bitstreams: 1 Silva_LuizAntonioda_M.pdf: 2904886 bytes, checksum: 2b2402e2537cbd9db0a35d64244be674 (MD5) Previous issue date: 2008 / Resumo: Este trabalho versa sobre métodos de levantamento de defeitos e avaliação das condições estruturais, funcionais e de segurança dos pavimentos asfálticos nas estradas estaduais sob a jurisdição do Departamento de Estradas de Rodagem do Estado de São Paulo - DER/SP. Aborda também alguns aspectos administrativos da Autarquia Estadual, aonde atuo como engenheiro de carreira na área de planejamento e de projeto. O DER/SP tem como missão administrar o sistema rodoviário estadual, sua integração com as rodovias municipais e federais e a sua interação com os demais modos de transporte, objetivando o atendimento aos usuários no transporte de pessoas e cargas. Para atender o crescimento acelerado da demanda de tráfego do Estado mais desenvolvido da Nação é imprescindível a ininterrupta execução de serviços de manutenção da rede existente e de construção de novas alternativas. Hoje com a relativa facilidade de acesso a uma ampla e variada tecnologia, aliada a uma crescente quantidade de boas empresas consultoras existentes no mercado, o DER/SP vem procurando desenvolver um Sistema de Gerência de Pavimentos (SGP-DER/SP). Enfim, o Estado de São Paulo que já teve no seu órgão rodoviário oficial a mais importante escola de rodoviarismo brasileira, está se adequando a um novo sistema de gestão para fazer jus à sua condição de principal Estado de um País de índole rodoviária. / Abstract: This master's thesis examines methods for survey and assessment of the structural, functional and safe conditions of asphalt pavements at the roads under the control of the Sao Paulo State Road Department (Departamento de Estradas de Rodagem do Estado de São Paulo - DER/SP). It also discusses some administrative aspects of the DER/SP, where I have worked as an engineer in the planning and project areas, which has the mission to manage the State road system, its integration with local and national roads and its interaction with other transport modes, aiming at providing transportation for people and cargo. In order to meet the fast growing traffic demand of the State of Sao Paulo, which is the most developed State of the country, it is vital to continuously keep the maintenance of the existing road net and the construction of new alternatives. Nowadays, with a relatively easy access to a wide range of technologies together with a growing supply of good consultancy companies, the DER/SP has attempted to develop a Pavements Management System (PMS-DER/SP). Therefore, the DER/SP, which once had been the most important brazilian road school, it has adapted itself to a new management system in order to be entitled to the position of the Road Department of the main State of the country, which is known for its road tradition. / Mestrado / Transportes / Mestre em Engenharia Civil

Please read the abstract in the section 00front of this document / Thesis (PhD (Engineering))--University of Pretoria, 2006. / Civil Engineering / unrestricted

No description available.

Highway alignment development is recognised as a non-linear constrained optimisation problem. It is affected by many economical, social, and environmental factors subject to many design constraints. The highway alignment development process is therefore considered complex but very important. Highway alignment development is about finding an optimum alignment solution between two termini points in a 3D space, subject to several constraints. The development process using the current method is considered complex because of the number of the design elements involved, their interactions, and the formulations required to relate them to a realistic highway alignment. Moreover, it is considered that an alignment, generated using the existing method, results in a sub-optimal solution. This is due to the fact that the two alignments (horizontal and vertical alignments) are found in two independent stages and from only a handful number of alternative evaluations. This research reports on a new approach for improving the process of highway alignment development by utilising modern technologies. It proposes a novel design approach, as an alternative to the existing method, for highway alignment development in a three-dimensional space (considering the horizontal and vertical alignments simultaneously). It describes a method for highway alignment development through station points. Station points, as points along the centre line of alignment which are defined by their X, Y, and Z coordinates, are used to define the alignment configuration. The research also considers the implications of access provision (in term of junctions) and their locations on highway alignment. The environmental factors (noise and air pollution in terms of proximity distance) and accessibility (user and link construction costs in terms of access costs) are embedded in the formulations required to represent junctions in the model. The proposed approach was tested through the development of a genetic algorithms based optimisation model. To achieve this, several algorithms were developed to perform the search. The evaluation of the solutions was handled by a fitness function that includes construction (length), location (land acquisition, environmentally sensitive areas, and soil condition), and earthwork (fill and cut material) dependent costs. Other forms of costs that are quantifiable can also be incorporated within the fitness function. The critical constraints, believed important for realistic alignments (horizontal curvature, vertical curvature, and maximum gradient) are also dealt with within the model formulation. The experimental results show that the problem of highway alignment can be better represented using the concept of station points, by which better alignment solutions (global or near global solutions) were achieved. It was also shown that the alignment development process could be simplified through the use of station points, resulting in the efficient evaluation of more alternatives. Furthermore, the results conclude that a highway alignment cannot be optimum unless it is simultaneously optimised with junctions. Further investigations and development are also recommended for future studies.

No description available.

No abstract available. / Thesis (Ph.D.)--University of Natal, Durban, 1984.

Eco-friendliness, energy efficiency and cost effectiveness are major drivers responsible for cold recycled asphalt mixtures being considered as alternatives to hot mixtures. Although such mixtures are still regarded in some quarters as second class asphalt, results from field trials on such materials under temperate climates have been reported to be highly impressive and encouraging. Some developed countries with temperate climates have since developed guidelines for the production and use of cold mixtures in road building. However, evidence from the literature shows that little or nothing has been done to ascertain the performance and suitability of such sustainable materials in developing countries located in hot tropical climates. Ascertaining the performances of such will, among other things enable the formulation of guidelines required for producing and using these alternative sustainable materials and methods in developing countries with hot tropical climates, where available funds for road building are increasingly inadequate to meet demand. The work reported in this thesis attempts to simulate what should be expected in terms of the performance of flexible pavements containing cold mixes of bitumen emulsion stabilized RAP as road base in hot climates. Cold recycling in-plant was deemed appropriate for the obvious reason that it enables control of the quality of mixtures produced. The challenge of sourcing severely aged RAPs required for this study afforded the opportunity of developing a laboratory ageing protocol for producing RAPs with controlled properties, typical of those found in hot tropical belts (with residual binders of very low penetration). The result of the physico-chemical and rheological studies showed that ageing hot mix asphalt at 125⁰C does not degrade the binder when compared to that aged at 85⁰C, which is the conventional protocol (for temperate climates). A target mix design based on Overseas Road Notes (ORN) 19 and 31 for 20mm DBM, which the literature suggests is suitable for road base layers of road pavements, yielded an aggregate gradation containing RAP (with residual bitumen of 20dmm penetration), 5mm granite dust and granite mineral filler in the proportion 65:30:5 respectively. Further investigations patterned after Marshall and Hveem mix design methods, indicated that a cationic bitumen emulsion content of 6.5% and pre-wetting water content of 1.5% were suitable. Unlike hot mixtures, cold mixtures due to their peculiarity i.e. intermediate nature (close to unbound granular materials in early life and close to fully bound materials when fully cured), require curing before being assessed for mechanical properties such as stiffness, strength etc. Performances of the five cold bituminous emulsions mixtures (CBEMs), one with 100% virgin aggregate, the others including RAP with binder penetrations 5, 10, 15 and 20dmm, manufactured at 20⁰C and 32⁰C (to reflect average minimum and maximum temperatures in hot tropical climates) showed that: • Properties of CBEM are dependent on the state of curing or maturation attained i.e. early life, intermediate life and fully cured or stable condition; • High air void content in CBEMs appears to be inevitable; • Mixing and compaction temperature is very important for achieving relatively low air void contents in CBEMs. For example, mixing and compacting CBEMs at 32⁰C gave better results than at 20⁰C; • Indirect Tensile Stiffness Modulus is useful for quickly ranking the CBEMs; • The RAP CBEMs performed better than the virgin aggregate CBEM in terms of water susceptibility; • An increase in stiffness modulus up the range from 10dmmCBEM to 15dmmCBEM and to 20dmmCBEM, with higher values than the virgin aggregate CBEM as observed in this work gives the impression that the residual binder in the studied RAPs is active as a result of possible softening or rejuvenation. Alternatively, the stiffness enhancements could possibly have been caused by the alteration of the volumetrics of such RAP CBEMs which consequently enhanced their compactability; • Overall, RAP CBEMs are better than virgin aggregate CBEM in mechanical performance and durability; • Fatigue lives of the CBEMs are generally lower than those for hot mix asphalt (HMA); • The CBEMs are stress-dependent as they all fitted the k-Θ model. The results of the analytical pavement design showed the importance of using tools such as KENLAYER which account for the non linearity of CBEMs. Although the structural design was a hypothetical case, the results confirmed that the virgin aggregate CBEM was inferior in terms of axle loads to failure compared to the RAP CBEMs, and the RAP CBEMs were inferior to HMA. The findings of this limited investigation suggest that the studied RAP CBEMs are suitable for low volume traffic roads, an indication of the great potential of these sustainable materials when properly harnessed. In the light of this, a short and concise set of guidelines for mix design of RAP CBEMs and structural design of pavements containing such non linear materials was proposed in the thesis.

This thesis is concerned with producing a simple method to design low volume roads (LVR) by means of a rationale which accounts for permanent deformation development in granular layers. Rutting is regarded as the main distress mode in unsealed and thinly sealed pavements. Hence, it is desirable that it be analytically approached rather than empirically, as in most design methods. The overall aim of this PhD thesis was to look into the behaviour of in-service roads and from a newly developed process, to advance, in a systematic manner, the elements required to produce a simple mechanistic design procedure. The study took as its basis an assessment of the proximity of the stress distribution in the pavement to the material’s failure envelope. After a literature review on unbound granular materials mechanical behaviour and on low volume roads pavement design methods, Chapters 4 and 5 discuss full scale trials carried out in Scotland on typical forest roads. The overall goal of the trials carried out within the Roads Under Timber Transport project was to establish the effect of weather and seasonal effects on the rutting of forest roads and to improve their performance while enabling the roads to be economically constructed and maintained. It appears that most of the rutting occurring in the sites surveyed came shortly after their construction/resurfacing, leading to the assumption that workmanship may be a highly important variable. Lack of compaction of the layer could be one of the likely reasons for the high initial rutting rates. Establishing the effect of weather on rutting further to the existing knowledge was, however, difficult to achieve; this was mainly due to the difficulties faced in monitoring traffic conditions. A newly developed method was needed to quantify permanent deformation development due to wandering traffic on a non-level pavement; this was achieved by the use of wheel path areas, and seemed to be a way forward in the analysis of rutting in unsealed roads. Accelerated pavement trials are reported that aimed to evaluate the performance of aggregate under soaked conditions and the relative pavement deformation caused by different timber haulage vehicles. A road segment simulating a standard forest road section was constructed in a purpose-built facility located at the Ringour Quarry facility. Ten different trials were carried out combining three different aggregate materials and five types of vehicles. Tyre fitment, axle configuration and tyre pressure were assessed and demonstrated to play an important role on the study of rutting development. Conclusions drawn from the results suggest that management of the tyre inflation pressure and axle overload may be one of the most economic means of managing pavement deterioration in the forest road network. A mechanistic analysis of a variety of unsealed pavements was carried out in Chapter 6; and the newly proposed methodology is described in Chapter 7. With changing loading conditions – e.g. as a consequence of the introduction of Tyre Pressure Control Systems and super single tyres – more detailed analyses are required, so that their effect can be analytically assessed. Then an analytical method is introduced for evaluating the stress-strain condition in thinly surfaced or unsurfaced pavements as typically used in LVR structures. It aims to improve the understanding of the effect of tyre pressure and contact area in regard to permanent deformation. To achieve this, several scenarios were modelled using Kenlayer software varying aggregate material, thickness, stiffness, tyre pressure & arrangement. The results usually show a fairly well defined locus of maximum stresses. By comparing this stress envelope with failure envelope, conclusions could be established about the more damaging effect of super singles over twin tyres and, likewise, the greater damage inflicted by high tyre pressures compared to that incurred by lower tyre pressures. Finally, the framework of the proposed method contributes to LVR pavement design procedures mainly due to its simplicity. It still treats the pavement analytically, permitting a more fundamental description of the behaviour of granular layers than in simple linear elastic analysis, but by simplifying the elasto-plastic analysis for routine use it thereby reduces demands of material characterization and computational skills, thus increasing its utility in practical application.

A significant growth has been shown in recycling of the old asphalt pavement as a technically and environmentally preferred way of rehabilitating the existing pavements during the three decades. However, savings acquired by using this technology may be lost through excessive maintenance processes if the recycled pavement exhibits too much deterioration. The current design methods for recycled HMA hypothesize a state of complete blending between the recycling agent and RAP binder. In practice, the complete blending does not occur as the recycling agent does not penetrate the whole layer of the aged binder around RAP particles (Carpenter and Wolosick, 1980). As a result of this, the resultant binder within the recycled mix differs from the desired binder, leading to dissimilarity in properties of the recycled and virgin mixes. Consequently, if the recycled mix was subjected to ageing and recycling for second time, the respond of its resultant binder will not the same as if it was the desire binder. This in turn may make the performance of recycled mix of second cycle differs from that of first cycle. Therefore studying the effect of repeated recycling on performance of the recycled HMA was the aim of this research. First, three types of RAP (reclaimed asphalt pavement) were manufactured in the laboratory and were utilized to produce three types of recycled HMA. After testing the recycled mixes, they were aged again to the same ageing time and temperature, then were crushed to be used as RAP for next generation of recycling. This process was repeated three times. Bitumen 40/60 pen and 70/100 pen were used for the virgin and recycled mixes respectively. All virgin and recycled mixes were designed to have identical aggregate grading, bitumen content, air voids, and binder viscosity. Stiffness and fatigue characteristics were measured after each cycle by the Indirect Tensile Stiffness Modulus test (ITSM) and Indirect Tensile Fatigue Test (ITFT). The results showed that, in spite of, presence deterioration in stiffness or fatigue resistance after the first cycle, the repeated recycling had no further significant effect on deterioration of these properties. Because there was considerable degradation in performance of recycled mixes after the first cycle, certain factors that were believed to improve the efficiency of mixing of these types of mixtures were investigated. These factors included size of RAP agglomeration, mixing temperature, dry mixing time between superheated aggregate and RAP, warming of RAP, and mixing mechanism. The results showed the importance of all factors in improving the mechanical properties of recycled mixes. However, the most influential factors were mixing temperature and warming of RAP. Durability of recycled mixes to resist moisture damage was assessed by the water sensitivity test. The results demonstrated that the recycled mixes were not susceptible to moisture damage and can resist the harmful action of water better than the virgin mix. An interesting element in this research was the possibility of using the Hirsch model to estimate the rheological properties of effective binder within recycled mixes without applying recovery process.