Thesis (MScEng (Mathematical Sciences. Applied Mathematics))--University of Stellenbosch, 2006. / This work entails the improvement of an existing three dimensional pore-scale model. Stagnant zones are included, the closure of the volume averaged pressure gradient is improved and an improved calculation of pore-scale averages, using the RUC, is done for the model to be a more realistic representative of the REV and thus of the foamlike material. Both the Darcy and the Forchheimer regimes are modelled and a general momentum transport equation is derived by means of an asymptotic matching technique. The RUC model is also extended to cover non-Newtonian flow. Since metallic foams are generally of porosities greater than 90%, emphasis is put on the accurate prediction of permeability for these porosities. In order to improve permeability predictions for these high porosity cases an adaptation to the RUC model was considered, whereby rectangular prisms were replaced by cylinders. Although this adaptation appears to give more accurate permeabilities at very high porosities, its implementation in a generalised model seems impractical. The prediction of the characteristic RUC side length is discussed and results of both the cylindrical strand model and the square strand model are compared to experimental work.

Made available in DSpace on 2014-12-17T14:08:50Z (GMT). No. of bitstreams: 1 MarcoABL_DISSERT.pdf: 3031485 bytes, checksum: ee9422376e7cb63c045cc578494d0199 (MD5) Previous issue date: 2011-02-08 / Cementing operations may occur at various stages of the life cycle of an oil well since its construction until its definitive abandonment. There are some situations in which the interest zones are depleted or have low fracture pressure. In such cases, the adoption of lowdensity cement slurries is an efficient solution. To this end, there are basically three ways to reduce the density of cement slurries: using microspheres, water extending additives or foamed cement. The objective of this study is to formulate, to study and to characterize lowdensity foamed cement, using an air entrainment surfactant with vermiculite or diatomite as water extenders and stabilizers. The methodology consists on preparation and evaluation of the slurries under the American Petroleum Institute (API) and the Brazilian Association of Technical Standards (ABNT) guidelines. Based on calculated densities between 13 and 15 ppg (1.559 and 1.799 g/cm3), the slurries were prepared with fixed surfactant concentration, varying the concentrations of vermiculite and diatomite and were compared with the base slurries. The results of plastic viscosity, yield point and gel strength and the compressive strength for 24 h showed that the slurries presented suitable rheology and mechanical strength for cementing operations in oil wells, and had their densities reduced between 8.40 and 11.89 ppg (1.007 and 1.426 g/cm3). The conclusion is that is possible, under atmospheric conditions, to obtain light weighted foamed cement slurries with satisfactory rheological and mechanical properties by means of air entrainment and mineral additions with extenders and stabilizers effects. The slurries have great potential for cementing operations; applicability in deep wells, in low fracture gradient formations and in depleted zones and bring cost savings by reducing the cementing consumption / As opera??es de cimenta??o podem ocorrer em diversas etapas do ciclo de vida de um po?o, desde a sua constru??o at? seu abandono definitivo. H? situa??es em que as zonas de interesse se apresentam depletadas ou com baixa press?o de fratura. Nesses casos, a ado??o de pastas cimentantes de baixa densidade constitui solu??o eficiente. Para tanto, h? basicamente tr?s maneiras de reduzir a densidade de pastas de cimento: usando microesferas, aditivos estendedores de ?gua ou pastas espumadas. O objetivo deste trabalho ? formular, estudar e caracterizar pastas cimentantes espumadas de baixa densidade, utilizando um surfactante incorporador de ar juntamente com adi??es de vermiculita ou diatomita como estendedores e estabilizantes. A metodologia do trabalho consiste na prepara??o e avalia??o das pastas por meio de procedimentos adotados pelo American Petroleum Institute (API) e pela Associa??o Brasileira de Normas T?cnicas (ABNT). Partindo de densidades calculadas entre 13 e 15 lb/gal (1,559 e 1,799 g/cm3), as pastas foram preparadas com dosagem fixa do surfactante, variando as concentra??es de vermiculita e diatomita e foram comparadas com pastas base. Os resultados dos ensaios que determinam viscosidade pl?stica, limite de escoamento e for?as g?is, bem como os de resist?ncia ? compress?o para tempos de 24 h mostraram que as pastas apresentaram reologia e resist?ncia mec?nica adequadas para opera??es de cimenta??o em po?os de petr?leo, al?m de terem suas densidades reduzidas entre 8,40 e 11,89 lb/gal (1,007 e 1,426 g/cm3). Conclui-se que ? poss?vel, sob condi??es atmosf?ricas, obter pastas cimentantes espumadas de baixa densidade com propriedades reol?gicas e mec?nicas satisfat?rias, por meio de incorpora??o de ar e adi??es minerais com efeitos estendedores e estabilizantes. As pastas possuem grande potencial para opera??es de cimenta??o, t?m aplicabilidade em po?os profundos, forma??es de baixo gradiente de fratura e zonas depletadas e trazem redu??es de custo pela diminui??o do consumo de cimento

A reciclagem profunda com espuma de asfalto tem sido uma alternativa de sucesso para a restauração de pavimentos degradados. Em relação às soluções tradicionais de reabilitação, como os recapeamentos, tem a vantagem de proporcionar a correção de defeitos em camadas inferiores, com a manutenção ou pequena elevação do greide da pista, além de ganhos ambientais, como um menor consumo de materiais virgens da natureza e redução do volume de material descartado. Entretanto, no Brasil não há método para dimensionamento estrutural para esta tecnologia, o que dificulta seu emprego. Para o desenvolvimento de um procedimento de dimensionamento que contemple este tipo de solução, foram estudados métodos presentes na bibliografia internacional: guia da AASHTO de 1993 e Caltrans, dos EUA, TRL386 e TRL611, da Inglaterra, as duas versões do guia sul-africano TG2 e os métodos oriundos do Austroads, tanto o procedimento interino de 2011 como adaptações de órgãos da Austrália e Nova Zelândia. Observou-se divergência de opiniões quanto ao comportamento do material reciclado com espuma de asfalto. Alguns órgãos e autores consideram o comportamento do mesmo mais próximo às misturas asfálticas, sendo o mecanismo de falha o trincamento, e outros o definem como semelhante a um material granular modificado com alta coesão e ruptura devido às deformações permanentes. Correlaciona-se tal associação ao teor de espuma usualmente utilizado nas obras rodoviárias. Outros aspectos que se destacam para este tipo de base são o ganho de resistência ao longo do tempo devido à cura, mesmo com início da operação da rodovia e a importância da infraestrutura remanescente no dimensionamento. Tais fatos foram corroborados pelos estudos de caso e resultados do trecho experimental construído na Rodovia Ayrton Senna - SP 070, monitorado por meio de ensaios deflectométricos com FWD durante um ano. Como resultado do trabalho, foi proposto um procedimento para o dimensionamento estrutural de pavimentos com camadas recicladas a frio com espuma de asfalto utilizando dados deflectométricos que atende o método do Manual de Pavimentação do Departamento Nacional de Infraestrutura de Transportes (DNIT) e incorpora diferentes aspectos na análise mecanicista. Outras conclusões são a viabilidade técnica a longo prazo da solução mencionada e a importância do controle tecnológico, com ênfase para o monitoramento deflectométrico nos primeiros meses de operação do pavimento para averiguar a evolução da cura do material. / Full-depth pavement reclamation with foamed asphalt has been a successful alternative for the rehabilitation of degraded pavements. In relation to the traditional rehabilitation methods, such as overlays, it has the advantage of provide the correction of the lower layer\'s defects considering the maintenance of the road grade or slight increase of it. Besides that, there are environmental gains, with less consumption for virgin materials and reduction of discarded material volume. However, in Brazil there is no structural design method for this technology, which hinders its use. To develop a design procedure which includes this kind of solution, several international methods were studied, like AASHTO (1993) and CALTRANS, from the USA; TRL386 and TRL611, from England; TG2 guide, from South Africa; and methods derived from the Austroads were studied, both, the interim procedure 2011 and local departments adaptations from Australia and New Zealand. There are divergent opinions of the behavior of the recycled material with foamed bitumen. Some agencies and authors consider the behavior of it similar to the asphalt mixtures, and the failure mechanism cracking due to fatigue. Others define it as similar to modified granular material with high cohesion and disruption due to permanent deformation. Such association is related to the foamed asphalt content usually used in road works. Other aspects that stand for such basecourse material are the gain of strength over time due to cure, even with the beginning of the highway operation and the importance of the remaining pavement\'s layers in design process. These facts were corroborated by case studies and results of the test section built in Ayrton Senna Highway - SP 070, which was monitored through falling weight deflectometer (FWD) measurements for a year. As result of this work, it is proposed a procedure for the structural design of cold recycled pavements with foamed asphalt using deflectometer data that meets the method of paving manual of the Brazilian National Department of Transport Infrastructure (DNIT). Other findings are the technical long-term viability of that solution and the importance of technological control, with emphasis on the deflection monitoring in early pavement operation to ascertain the evolution of the curing process.

Due to the rising demand of light-weight constructions as well as the conservation of resources, the density and weight of thermoplastic parts could be influenced significantly by using the thermoplastic foam injection molding process. The structure of the foam injection molded part, which typically means solid surface layers and a cellular core, usually results in a weight saving. Furthermore the materials structure leads to an increasing of the specific bending stiffness with a simultaneous low tendency to warp. The present study was aimed to analyze the interactions between microcellular structure, joining process and the resulting mechanical properties of the molded part. Therefore, the microcellular injection molding process (MuCell®) as well as the vibration welding were used. Whereas the established welding processes for solid injection molded parts have already achieved a high degree of perfection within the last decades, the joining of microcellular thermoplastics entails several specific characteristics, because the injection foaming process highly influences the basic material properties. In contrast to solid materials, the weld seam properties after joining are mainly affected by the design constraints of the microcellular structure.

Les mousses minérales sont des matériaux alvéolaires utilisables en isolation thermique répartie. L’objectif de ces travaux de recherche est de développer, à partir d’une suspension très concentrée de liants hydrauliques, des mousses légères présentant de bonnes performances mécaniques et thermiques. L’introduction de tensioactif est nécessaire à la formation des mousses minérales. Six molécules tensioactives sont sélectionnées dans cette étude. Leurs capacités à réduire la tension de surface et à stabiliser une mousse aqueuse sont évaluées. Deux groupes de tensioactifs sont distingués sur la base de différents critères : tension de surface, CMC, stabilité de la mousse. Les suspensions minérales concentrées sont des fluides à seuil. L’étude du comportement de bulles formées dans de tels fluides est réalisée à l’aide d’un fluide à seuil modèle transparent, le Carbopol®, et d’un système d’injection à pression contrôlée. Le seuil de mise en écoulement affecte les conditions de formation, de croissance, de stabilité et d’évolution de la forme des bulles en modifiant la distribution des pressions au voisinage de la bulle. L’étude permet de proposer une équation de Laplace modifiée prenant en compte l’influence de la sphéricité et du seuil de cisaillement. L’introduction du tensioactif affecte les conditions de contact entre bulles et permet de contrôler le risque de coalescence. En cas de rupture de membrane, la présence du seuil de cisaillement conduit à une géométrie particulière des bulles coalescées. Les liants minéraux choisis sont un sulfate de calcium anhydre particulièrement réactif, un ciment Portland et un ciment prompt. La formulation des suspensions découle d’un critère de fluidité. La pâte fraîche est caractérisée par un seuil de cisaillement faible. Sa masse volumique apparente dépend de la nature et du dosage en tensioactif. Les mousses minérales sont générées à partir d’une composition identique. Deux méthodes de moussage traditionnelles : malaxage simple et mousse préformée et une méthode alternative : la méthode dissociée, sont exploitées. Les meilleures performances thermomécaniques des mousses durcies sont obtenues avec la méthode dissociée, méthode spécifique au laboratoire et peu énergivore. Un groupe de tensioactifs permet d’obtenir des mousses peu denses satisfaisant simultanément aux critères de performances thermomécaniques fixés. Pour ces tensioactifs, un dosage caractéristique est identifié permettant une optimisation des performances mécaniques. Des visualisations réalisées au MEB révèlent des modifications sensibles de la structure cristalline fonction du tensioactif employé et de son dosage. Les structures les plus fines et homogènes sont les plus résistantes. Les performances des mousses et leur structure porale sont donc liées. Pour analyser quantitativement la structure porale, les distributions alvéolaires surfaciques sont construites puis comparées aux distributions alvéolaires volumiques obtenues par tomographie. Une méthode analytique de passage 2D/3D est créée en s’appuyant sur les principes de la stéréologie. Un coefficient de correction est proposé pour tenir compte de la représentativité de la surface étudiée. La maîtrise de toutes les étapes de fabrication des mousses minérales ainsi que la compréhension des phénomènes physiques intervenant tout au long de la production d’une mousse (de la suspension minérale jusqu’à la mousse durcie) permettent d’obtenir des produits satisfaisant les objectifs fixés : légèreté, isolation et caractère porteur. / Mineral foams are cellular materials usable as thermal insulation solution. The purpose of these PhD researches is to develop lightweight foams with good thermal and mechanical performances realized from highly concentrated mineral suspension. Surfactant addition is required for foaming. Six surfactants molecules are selected. Their abilities to reduce surface tension and to stabilize aqueous foam are evaluated. Two surfactants groups are detected based on different criteria: surface tension, CMC and aqueous foam stability. Concentrated mineral suspensions are yield stress fluids. The study of bubbles behavior in such fluids is performed with a transparent yield stress fluid, Carbopol® and an injection device with controlled pressure. Yield stress impacts bubbles creation, growth, stability and shape by changing local pressure distribution in the fluid nearby bubble. The study proposes a revised Laplace law depending on yield stress and bubble sphericity. Contact conditions between bubbles are influenced by surfactant addition allowing to control coalescence phenomena. In case of inter-bubbles membrane breakage, presence of yield stress leads to particular geometry of the coalesced bubbles. Mineral binders selected are a highly reactive anhydrous calcium sulfate, ordinary Portland and prompt cements. Mineral suspension formulations arise from expected fluidity criterion. Fresh paste is characterized by a low yield stress. Its bulk density depends on surfactant nature and content. Mineral foams are created with same composition. Two traditional foaming methods: mix-foaming and pre-foaming and an alternative one, the dissociated method are employed. Best thermo-mechanical performances are achieved with the dissociated method, a specific method of the laboratory. A surfactant group leads to lightweight foams which simultaneously fulfills both thermal and mechanical targeted objectives. For these surfactants a characteristic content is found leading to optimized mechanical performances. Visualizations performed with SEM reveal sensitive crystalline structure modifications depending on surfactant nature and content. Thinner and more homogeneous structures are associated with the best mechanical performances which demonstrates the existing link between the porous structure and mineral foams mechanical performances. To quantitatively evaluate porous structure, surface bubble-size distributions are built and then compared to volume bubble-size distributions obtained by tomography analysis. An analytic method linking 2D and 3D distributions is created based on stereology principles. A correction coefficient is proposed to take into account the analyzed representative surface. By controlling all production steps and associated physical phenomena during mineral foams production (from mineral suspension to solid foams), products satisfying all targeted objectives are realized: lightness, insulation and load-bearing ability.

No description available.

Excessive fluid-borne noise in hydraulic systems is a problem the fluid power industry has long struggled to address. Traditional noise control devices such as Helmholtz resonators, tuning coils, and Herschel-Quincke tubes are generally too large for fluid power systems unless the speed of sound in the device can be reduced. A compliant lining can achieve this effect, but compliance (and lossy compliance) has had little attention in noise control in general, and in fluid power in particular. One means to achieve compliance in these devices, especially at elevated pressures, is through a liner made of syntactic foam, which in this case is a urethane host matrix with embedded hollow, polymer microspheres. The material properties at elevated pressure are unknown by the liner manufacturer, but are known to be pressure- and temperature-dependent. Therefore, the effect of hydrostatic pressures from 2.1-21 MPa and temperatures from 20-45 C on the liner properties, thus the device performance, are studied. For a Helmholtz resonator, a theoretical model is fit to experimentally-measured transmission loss of the device using a least-squares routine, which solves the inverse problem for the complex bulk modulus of the liner. These material properties are used to compare a predictive model of a tuning coil to experimental data, and in a parameter study of a Herschel-Quincke tube. The compliance of the liner is found to lower the effective sound speed by an order of magnitude and decrease the volume of the cavity of a Helmholtz resonator by up to two orders of magnitude. This work is expected to result is more compact noise control devices for fluid power systems.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The increased use of reclaimed asphalt (RA) in Bitumen Stabilised Materials (BSMs), shortcomings in the existing design guidelines and manuals and ongoing developments in the concepts and understanding of these materials require further research into the fundamental properties and behaviour of BSMs. The state-of-the-art of foamed bitumen techniques is reviewed in the literature study. Current best practices in the design of BSMs and pavements incorporating such materials are also included in this literature study. Shortcomings and areas for further improvement of the design practice have been identified. With new environmental legislation, the importance of BSM technology including RA as an environmentally-friendlier and more sustainable construction technique is set to increase in the coming years. Changes in the behaviour of materials and failure mechanisms of BSM mixes are long-term phenomena. This implies that the study of the physico-chemical and mechanical properties of the mixes with increasing amount of RA is vital. Therefore, fundamental understandings of moisture damage and thermo-physical characteristics, which are related to material properties, are required. The main objective of this study is to advance BSM technology by assessing the influence of the selected materials on durability behaviour, temperature distribution and long-term performance in all phases of application (i.e. mix design, construction, and in-service condition). This study begins with a comprehensive literature review of research dealing with the interactions between RA and mineral aggregates. The properties of RA and mineral aggregates were reviewed. This was followed by a review into the mechanical properties of BSM-foam mixes with high percentage of RA and its durability performance. Factors influencing the temperature gradient of BSMs were then identified. Achieving a better understanding of the fundamental performance properties and temperature influence on the behaviour of BSMs with high percentage of RA is one of the key factors of this research, with a view to using the extended knowledge for improvements to current mix design and structural design practices. Finally, the fundamental theories on thermo-conductivity and the mechanical properties of the BSM were used to create a relationship between temperature and mechanical properties in a pavement section. A laboratory testing programme was set up to study the properties and behaviour of BSMs and to establish links with the compositional factors, i.e. the type of binder used, the percentage of RA in the mix and the addition of a small amount of cement as active filler. BSMs were blended in three different proportions of RA and good quality crushed stone materials: 100% RA (with 2 % bitumen content), 50% RA and 50% G2 Hornfels crushed stone (with 2.1% bitumen content) and 100% G2 (with 2.3 % bitumen content). Tri-axial testing was carried out to determine shear parameters, resilient modulus and permanent deformation behaviour, while brushing testing was carried out to determine the possible durability performance of the BSMs. The mixture durability in terms of moisture damage was investigated. Temperature data were collected and a model to accurately simulate the temperature distribution in the BSMs was identified and proposed for further investigation and validation. It was found from the laboratory temperature data collected in this study that the temperature gradient varied according to the depth of the BSMs. A considerable part of the efforts of this study were dedicated to characterise and model the temperature distribution in a pavement section, taking into account the mechanical properties and performance of the BSMs at different temperature layers. The study provides an insight into fundamental mechanical performance, material durability properties, and the thermal capacity and conductivity of the BSM-foam mixes with high percentage of RA. This will assist in improving the current procedure for selection, combining and formulation of the mix matrices for BSMs. In addition, the study provides guidelines that will enable practitioners to confidently understand the relationship between temperature gradient and mechanical behaviours of BSM-foam pavement section. The specific durability-related issues addressed in this study are substance for future research. / AFRIKAANSE OPSOMMING: Die toenemende gebruik van herwonne asfalt (Engels: reclaimed asphalt (RA)) in bitumen gestabiliseerde materiaal (Engels: Bitumen Stabilised Materials (BSMs)), tekortkominge in die bestaande ontwerpriglyne- en handleidings en deurlopende verbeteringe in die konsepte en begrip van hierdie material vereis verdere navorsing oor die fundamentele eienskappe en gedrag van BSM. In die literatuurstudie word die huidige stand van kennis van die ontwerp van skuimbitumentegnieke ondersoek. Die literatuurstudie dek ook die huidige beste praktyke in die ontwerp van BSM en plaveisels wat hierdie materiale insluit. Tekortkominge en areas van verdere verbetering in die ontwerppraktyke is geïdentifiseer. Onlangse omgewingswetgewing verhoog die belangrikheid van BSM tegnologie, insluitend RA, as ‘n meer omgewingsvriendelike en volhoubare konstruksie-tegniek. Hierdie faktor sal in die toekoms al hoe belangriker word. Die verandering in die gedrag van materiaal en die falingsmeganismes van BSM mengsels is langtermynverskynsels. Dit impliseer dat die studie van die fisio-chemiese en meganiese eienskappe van mengsels met toenemende verhoudings van RA van kardinale belang is’n Fundamentele begrip van die vogskade en temo-fisiese eienskappe, wat verwant is aan die materiale se eienskappe, word vereis. Die primêre doelwit van die studie is die bevordering van BSM tegnologie deur die invloed van die geselekteerde materiale op duursaamheid, temperatuurverspreiding en langtermyn gedrag in al die fases van toepassing (mengselontwerp, konstruksie en in-dienstoestand) te bepaal. Die verhandeling begin met ‘n omvattende literatuuroorsig van navorsing oor die interaksie tussen RA en mineraalaggregate. Die eienskappe van RA en die mineraalaggregate word bespreek. Dit word gevolg deur ‘n oorsig van die meganiese eienskappe van die BSM-skuimbitumenmengsels met ‘n hoë persentasie RA en die duursaamheidgedrag daarvan. Faktore wat die temperatuurgradient van BSM beïnvloed word dan aangetoon. ‘n Beter begrip van die fundamentele gedragseienskappe en die invloed van temperatuur op die gedrag van BSM met ‘n hoë persentasie RA is een van die sleutelfaktore van hierdie navorsing. Dit het ten doel om die uitgebreide kennis te gebruik om huidige mengselontwerp en strukturele ontwerppraktyke te verbeter. Laastens is die fundamentele teorie van termogeleiding en die meganiese eienskappe van BSM gebruik om ‘n verhouding tussen temperature en meganiese eienskappe in ‘n plaveiselsnit te ontwikkel. ‘n Laboratoriumtoetsprogram is opgestel om die eienskappe en gedrag van BSM te bestudeer en om verwantskappe tussen samestellende faktore soos die tipe bindmiddel gebruik, die persentasie RA in die mengsel en die toediening van klein hoeveelhede sement as aktiewe vuller te bepaal. BSM is in drie verskillende verhoudings van RA en goeie gehalte gebreekte klipmateriaal vermeng: 100% RA met 2 % bitumen, 50% RA en 50 % G2 Hornfels gebreekte klip met 2.1 % bitumen en 100% G2 met 2.3 % bitumen. Drie-assige druktoetse is gebruik om skuifsterkteparameters, elastiese modulus en permanente vervormingsgedrag te bepaal. Borseltoetse is gebruik om die duursaamheidgedrag van BSM te bepaal. Die mengsels se duursaamheid is ook in terme van vogskade ondersoek.

Em busca de soluções estruturais para restauração de pavimentos rodoviários que que sejam eficientes, mas ao mesmo tempo que sejam econômicas e impactem o mínimo possível na dinâmica de operação da malha rodoviária, tem sido difundida a metodologia de reciclagem a frio de pavimentos com a estabilização com espuma de asfalto. A redução de custos devido a reutilização de material e a menor necessidade de transporte de insumos, além da possibilidade de realização da restauração em um curto espaço de tempo, têm contribuído para a crescente utilização do processo. Este trabalho tem como objetivo avaliar o desempenho e o comportamento mecânico de uma mistura reciclada estabilizada com espuma asfalto, para melhor entender os efeitos do confinamento e do teor de umidade do material, visto que este passa por um processo de cura quando já em serviço. Foi acompanhado um trecho experimental onde o pavimento foi restaurado com a aplicação de uma base reciclada estabilizada com espuma de asfalto. O segmento foi monitorado através do controle tecnológico de execução e de levantamentos deflectométricos com FWD. Verificou-se que as deflexões após quase 24 meses da execução do trecho reduziram consideravelmente. Paralelamente, foram realizados ensaios de resistência à tração por compressão diametral, módulo de resiliência triaxial e de deformação permanente para diferentes procedimentos de cura para verificação do efeito da saída da água nas mudanças de comportamento mecânico do material. Verificou-se ainda o efeito das tensões de confinamento no módulo de resiliência de materiais estabilizados com espuma de asfalto e determinaram-se os parâmetros de cisalhamento do material através de ensaiosTriaxiais Monotônicos. Pode-se concluir que a cura é uma consideração importante tanto com relação a sua duração, quanto com relação ao seu efeito no comportamento do material. / Seeking for pavement rehabilitation solutions that result in efficient and capable structures, that bring economic advantages, and the smallest possible impact to the road network operation, cold recycling with foamed asphalt stabilization has been gaining acceptance and growing steadily. The possibility of economic benefits due to material reuse and the decrease in transportation costs, allied to the reduced time needed to open to traffic, have contributed to the increase in this technique\'s use. This study has the objective of evaluating the performance of cold recycled mixes stabilized with foamed asphalt, for a better understanding on the effects of confining stresses, and material moisture content, since it undergoes the curing process when in service. An experimental test section with foamed stabilized recycled material used as the base course was monitored through quality control and quality assurance and FWD tests. It was observed that deflections, after nearly 24 months, have decreased significantly. In laboratory, Indirect Tensile Strength, Triaxial Resilient Modulus, and Permanent Deformation Tests were conducted for samples cured through different procedures, to evaluate the stress dependency and the effect of moisture decrease on the material behaviour. As a complementing test to evaluate the effect of confinement on material mechanical behaviour and to characterize the shear properties in foamed stabilized materials, a Monotonic Triaxial Test was performed. Based on the results obtained, one can conclude that the curing is a critical consideration in terms of timing and its influence on pavement performance. Triaxial tests showed the stress dependency of this bitumen stabilized material, while permanent deformation results indicated some potential for damage in the early stages after construction. Also, foamed bitumen stabilized materials stress dependency indicate that its mechanical behaviour is similar to unbound granular materials. On the field evaluation, FWD data indicated the decrease in deflection with time, resulting in an increase of the layers stiffness.

Em busca de soluções estruturais para restauração de pavimentos rodoviários que que sejam eficientes, mas ao mesmo tempo que sejam econômicas e impactem o mínimo possível na dinâmica de operação da malha rodoviária, tem sido difundida a metodologia de reciclagem a frio de pavimentos com a estabilização com espuma de asfalto. A redução de custos devido a reutilização de material e a menor necessidade de transporte de insumos, além da possibilidade de realização da restauração em um curto espaço de tempo, têm contribuído para a crescente utilização do processo. Este trabalho tem como objetivo avaliar o desempenho e o comportamento mecânico de uma mistura reciclada estabilizada com espuma asfalto, para melhor entender os efeitos do confinamento e do teor de umidade do material, visto que este passa por um processo de cura quando já em serviço. Foi acompanhado um trecho experimental onde o pavimento foi restaurado com a aplicação de uma base reciclada estabilizada com espuma de asfalto. O segmento foi monitorado através do controle tecnológico de execução e de levantamentos deflectométricos com FWD. Verificou-se que as deflexões após quase 24 meses da execução do trecho reduziram consideravelmente. Paralelamente, foram realizados ensaios de resistência à tração por compressão diametral, módulo de resiliência triaxial e de deformação permanente para diferentes procedimentos de cura para verificação do efeito da saída da água nas mudanças de comportamento mecânico do material. Verificou-se ainda o efeito das tensões de confinamento no módulo de resiliência de materiais estabilizados com espuma de asfalto e determinaram-se os parâmetros de cisalhamento do material através de ensaiosTriaxiais Monotônicos. Pode-se concluir que a cura é uma consideração importante tanto com relação a sua duração, quanto com relação ao seu efeito no comportamento do material. / Seeking for pavement rehabilitation solutions that result in efficient and capable structures, that bring economic advantages, and the smallest possible impact to the road network operation, cold recycling with foamed asphalt stabilization has been gaining acceptance and growing steadily. The possibility of economic benefits due to material reuse and the decrease in transportation costs, allied to the reduced time needed to open to traffic, have contributed to the increase in this technique\'s use. This study has the objective of evaluating the performance of cold recycled mixes stabilized with foamed asphalt, for a better understanding on the effects of confining stresses, and material moisture content, since it undergoes the curing process when in service. An experimental test section with foamed stabilized recycled material used as the base course was monitored through quality control and quality assurance and FWD tests. It was observed that deflections, after nearly 24 months, have decreased significantly. In laboratory, Indirect Tensile Strength, Triaxial Resilient Modulus, and Permanent Deformation Tests were conducted for samples cured through different procedures, to evaluate the stress dependency and the effect of moisture decrease on the material behaviour. As a complementing test to evaluate the effect of confinement on material mechanical behaviour and to characterize the shear properties in foamed stabilized materials, a Monotonic Triaxial Test was performed. Based on the results obtained, one can conclude that the curing is a critical consideration in terms of timing and its influence on pavement performance. Triaxial tests showed the stress dependency of this bitumen stabilized material, while permanent deformation results indicated some potential for damage in the early stages after construction. Also, foamed bitumen stabilized materials stress dependency indicate that its mechanical behaviour is similar to unbound granular materials. On the field evaluation, FWD data indicated the decrease in deflection with time, resulting in an increase of the layers stiffness.