This thesis is devoted to understanding solute-solvent interactions in folded and unfolded proteins. To this end, we have studied partial molar volume, Vo, and adiabatic compressibility, KoS, of 20 amino acid side chains using low weight molecular model compounds, N-acetyl amino acid amide and its derivatives, between 18 oC and 55 oC. We used our data to develop an additive scheme for calculating the partial specific volume and adiabatic compressibility of fully extended polypeptide chains as a function of pH and temperature. We compared our calculated volumetric characteristics of the fully extended conformations of apocytochrome c and apomyoglobin with the experimental values measured in neutral pH (for apocytochrome c) or acidic pH (for apomyoglobin). The comparison between the calculated and experimental volumetric characteristics suggested that neither apocytochrome c nor apomyoglobin are fully unfolded and retain solvent-inaccessible amino acid residues. To study cosolvent-solute interactions, we determined Vo and KoS of amino acid side chains and glycyl units as a function of urea concentration. We analyzed these data within the framework of a statistical thermodynamic formalism to determine the association constants, k, for the reaction in which urea binds to each of the amino acid side chains and the glycyl unit replacing two water molecules in solvation shell. Our determined k range from 0.04 to 0.39 M with the average of 0.16 ± 0.09 M. There was no apparent correlation between the values of k and the ratio of polar to nonpolar solvent accessible surface areas. This study supports a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. In addition, we have presented buffer ionization effect on the volume of protein denaturation could be significant with the potential to affect not only its magnitude but also its sign using a pressure perturbation calorimetric technique. Our results identified buffer ionization as an important determinant of protein transition volume that needs to be carefully taken into account. Results described in this work provide fundamental understanding of solute-solvent interaction in both folded and unfolded proteins.

This thesis is devoted to understanding solute-solvent interactions in folded and unfolded proteins. To this end, we have studied partial molar volume, Vo, and adiabatic compressibility, KoS, of 20 amino acid side chains using low weight molecular model compounds, N-acetyl amino acid amide and its derivatives, between 18 oC and 55 oC. We used our data to develop an additive scheme for calculating the partial specific volume and adiabatic compressibility of fully extended polypeptide chains as a function of pH and temperature. We compared our calculated volumetric characteristics of the fully extended conformations of apocytochrome c and apomyoglobin with the experimental values measured in neutral pH (for apocytochrome c) or acidic pH (for apomyoglobin). The comparison between the calculated and experimental volumetric characteristics suggested that neither apocytochrome c nor apomyoglobin are fully unfolded and retain solvent-inaccessible amino acid residues. To study cosolvent-solute interactions, we determined Vo and KoS of amino acid side chains and glycyl units as a function of urea concentration. We analyzed these data within the framework of a statistical thermodynamic formalism to determine the association constants, k, for the reaction in which urea binds to each of the amino acid side chains and the glycyl unit replacing two water molecules in solvation shell. Our determined k range from 0.04 to 0.39 M with the average of 0.16 ± 0.09 M. There was no apparent correlation between the values of k and the ratio of polar to nonpolar solvent accessible surface areas. This study supports a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. In addition, we have presented buffer ionization effect on the volume of protein denaturation could be significant with the potential to affect not only its magnitude but also its sign using a pressure perturbation calorimetric technique. Our results identified buffer ionization as an important determinant of protein transition volume that needs to be carefully taken into account. Results described in this work provide fundamental understanding of solute-solvent interaction in both folded and unfolded proteins.

A reciclagem profunda com adição de cimento Portland é uma técnica de recuperação estrutural e funcional de pavimentos empregada há muitos anos no país, devido a vantagens técnicas, econômicas e ambientais. Contudo, a difusão mais ampla da técnica esbarra na carência de normas e procedimentos nacionais, o que resulta na adoção de variados critérios nos projetos que incluem reciclagem com cimento, às vezes, comprometendo sua eficácia. A pesquisa relatada nesta dissertação teve por objetivo principal estabelecer as bases para a proposição de um método de dosagem para reciclagem de pavimentos com adição de cimento, considerando-se como referência o método de dosagem de materiais estabilizados com cimento da Austroads (2002). Para verificar a validade deste método para materiais de pavimentos brasileiros, desenvolveu-se um programa experimental no qual foram avaliadas propriedades mecânicas (resistência, rigidez e erodibilidade) e volumétricas (retração, absorção, expansão e ascensão capilar) de misturas constituídas por fresado asfáltico, brita graduada e cimento, variando-se a porcentagem de fresado (20% e 50%), o teor de cimento (2%, 4% e 6%), a energia de compactação (Intermediária e Modificada) e o tempo de cura dos corpos de prova (3, 7 e 14 dias). Os resultados dos ensaios mostraram que todas as variáveis analisadas afetam significativamente a resistência à compressão simples, a resistência à tração por compressão diametral e o módulo de resiliência das misturas, enquanto que a retração, a erodibilidade, a absorção, a expansão e a ascensão capilar são afetadas por algumas das variáveis independentes. Dentre outras conclusões, destaca-se que são obtidos elevados valores de resistência à compressão simples (1,61 MPa a 6,08 MPa), resistência à tração por compressão diametral (0,29 MPa a 1,00 MPa) e de módulo de resiliência (10390 MPa a 25719 MPa) com teores baixo (2%) e médio (4%) de cimento, sendo desnecessário e arriscado, pela elevada retração associada, o emprego de teor mais elevado (6%). Ainda, observou-se que o aumento da energia de compactação permite compensar a utilização de teores mais baixos de cimento no que se refere às resistências (à compressão, à tração e à erosão) e módulos obtidos. Globalmente, conclui-se que o método de dosagem de materiais estabilizados com cimento da Austroads (2002) pode ser usado como modelo para o desenvolvimento de um método de dosagem para reciclagem de pavimentos com adição de cimento, sendo necessárias pequenas complementações ou adaptações. O método de dosagem sugerido nesta Dissertação é, ao mesmo tempo, simples o suficiente para ser empregado em laboratórios de canteiros de obra e amplo o bastante para identificar as propriedades mecânicas e volumétricas que devem ser avaliadas ao elaborar-se um projeto de mistura reciclada com cimento. / Full-depth reclamation (FDR) with Portland cement is a technique used for structural and functional rehabilitation of pavements and has been used in Brazil for many years, especially because its technical, economical and environmental advantages. However, a larger diffusion of the technique has been inhibited by the lack of national standards and procedures, resulting in the adoption of different design criteria, which sometimes leads to a low efficiency of the FDR with cement. This research was carried out with the objective of setting the basis for a mix design method for FDR with cement, considering the Austroads (2002) mix design method for stabilized pavement materials as a model. In order to verify the applicability of the Austroads method to Brazilian pavement materials, an experimental program was carried out testing mechanical (strength, stiffness and durability) and volumetric (drying shrinkage, absorption, swell and capillary rise) properties of mixtures made of reclaimed asphalt pavement (RAP), graded crushed stone and cement. Specimens with different RAP contents (20% and 50%), cement contents (2%, 4% and 6%), compacted with two different efforts (Brazilian Intermediate and Modified) were cured for 3, 7 and 14 days. Test results showed that all the studied variables affect the unconfined compressive strength, indirect tensile strength and resilient modulus of the mixtures, while drying shrinkage, erodibility, absorption, swell and capillary rise are affected by some of the independent variables. Among other conclusions, it is pointed out that high values of unconfined compressive strength (1,61 MPa to 6,08 MPa), indirect tensile strength (0,29 MPa to 1,00 MPa) and resilient modulus (10390 MPa to 25719 MPa) may be achieved with low (2%) and intermediary (4%) cement contents, thus making the use of higher (6%) cement content unnecessary and unsafe, due to the higher costs and to the drying shrinkage associated. It was also observed that increases in the compaction effort may compensate the use of lower cement contents as regards to strengths and moduli obtained. Generally, can be concluded that the Austroads (2002) mix design method for stabilized pavement materials may be used as a model for the development of a mix design method for FDR with cement, being necessary only a few additions or adaptations. The suggested method is, simultaneously, simple enough to be used in field laboratories and comprehensive enough for including the mechanical and volumetric properties that must be evaluated when designing a mix for FDR with cement.

A reciclagem profunda com adição de cimento Portland é uma técnica de recuperação estrutural e funcional de pavimentos empregada há muitos anos no país, devido a vantagens técnicas, econômicas e ambientais. Contudo, a difusão mais ampla da técnica esbarra na carência de normas e procedimentos nacionais, o que resulta na adoção de variados critérios nos projetos que incluem reciclagem com cimento, às vezes, comprometendo sua eficácia. A pesquisa relatada nesta dissertação teve por objetivo principal estabelecer as bases para a proposição de um método de dosagem para reciclagem de pavimentos com adição de cimento, considerando-se como referência o método de dosagem de materiais estabilizados com cimento da Austroads (2002). Para verificar a validade deste método para materiais de pavimentos brasileiros, desenvolveu-se um programa experimental no qual foram avaliadas propriedades mecânicas (resistência, rigidez e erodibilidade) e volumétricas (retração, absorção, expansão e ascensão capilar) de misturas constituídas por fresado asfáltico, brita graduada e cimento, variando-se a porcentagem de fresado (20% e 50%), o teor de cimento (2%, 4% e 6%), a energia de compactação (Intermediária e Modificada) e o tempo de cura dos corpos de prova (3, 7 e 14 dias). Os resultados dos ensaios mostraram que todas as variáveis analisadas afetam significativamente a resistência à compressão simples, a resistência à tração por compressão diametral e o módulo de resiliência das misturas, enquanto que a retração, a erodibilidade, a absorção, a expansão e a ascensão capilar são afetadas por algumas das variáveis independentes. Dentre outras conclusões, destaca-se que são obtidos elevados valores de resistência à compressão simples (1,61 MPa a 6,08 MPa), resistência à tração por compressão diametral (0,29 MPa a 1,00 MPa) e de módulo de resiliência (10390 MPa a 25719 MPa) com teores baixo (2%) e médio (4%) de cimento, sendo desnecessário e arriscado, pela elevada retração associada, o emprego de teor mais elevado (6%). Ainda, observou-se que o aumento da energia de compactação permite compensar a utilização de teores mais baixos de cimento no que se refere às resistências (à compressão, à tração e à erosão) e módulos obtidos. Globalmente, conclui-se que o método de dosagem de materiais estabilizados com cimento da Austroads (2002) pode ser usado como modelo para o desenvolvimento de um método de dosagem para reciclagem de pavimentos com adição de cimento, sendo necessárias pequenas complementações ou adaptações. O método de dosagem sugerido nesta Dissertação é, ao mesmo tempo, simples o suficiente para ser empregado em laboratórios de canteiros de obra e amplo o bastante para identificar as propriedades mecânicas e volumétricas que devem ser avaliadas ao elaborar-se um projeto de mistura reciclada com cimento. / Full-depth reclamation (FDR) with Portland cement is a technique used for structural and functional rehabilitation of pavements and has been used in Brazil for many years, especially because its technical, economical and environmental advantages. However, a larger diffusion of the technique has been inhibited by the lack of national standards and procedures, resulting in the adoption of different design criteria, which sometimes leads to a low efficiency of the FDR with cement. This research was carried out with the objective of setting the basis for a mix design method for FDR with cement, considering the Austroads (2002) mix design method for stabilized pavement materials as a model. In order to verify the applicability of the Austroads method to Brazilian pavement materials, an experimental program was carried out testing mechanical (strength, stiffness and durability) and volumetric (drying shrinkage, absorption, swell and capillary rise) properties of mixtures made of reclaimed asphalt pavement (RAP), graded crushed stone and cement. Specimens with different RAP contents (20% and 50%), cement contents (2%, 4% and 6%), compacted with two different efforts (Brazilian Intermediate and Modified) were cured for 3, 7 and 14 days. Test results showed that all the studied variables affect the unconfined compressive strength, indirect tensile strength and resilient modulus of the mixtures, while drying shrinkage, erodibility, absorption, swell and capillary rise are affected by some of the independent variables. Among other conclusions, it is pointed out that high values of unconfined compressive strength (1,61 MPa to 6,08 MPa), indirect tensile strength (0,29 MPa to 1,00 MPa) and resilient modulus (10390 MPa to 25719 MPa) may be achieved with low (2%) and intermediary (4%) cement contents, thus making the use of higher (6%) cement content unnecessary and unsafe, due to the higher costs and to the drying shrinkage associated. It was also observed that increases in the compaction effort may compensate the use of lower cement contents as regards to strengths and moduli obtained. Generally, can be concluded that the Austroads (2002) mix design method for stabilized pavement materials may be used as a model for the development of a mix design method for FDR with cement, being necessary only a few additions or adaptations. The suggested method is, simultaneously, simple enough to be used in field laboratories and comprehensive enough for including the mechanical and volumetric properties that must be evaluated when designing a mix for FDR with cement.

A reciclagem profunda com adição de cimento Portland é uma técnica de recuperação estrutural e funcional de pavimentos empregada há muitos anos no país, devido a vantagens técnicas, econômicas e ambientais. Contudo, a difusão mais ampla da técnica esbarra na carência de normas e procedimentos nacionais, o que resulta na adoção de variados critérios nos projetos que incluem reciclagem com cimento, às vezes, comprometendo sua eficácia. A pesquisa relatada nesta dissertação teve por objetivo principal estabelecer as bases para a proposição de um método de dosagem para reciclagem de pavimentos com adição de cimento, considerando-se como referência o método de dosagem de materiais estabilizados com cimento da Austroads (2002). Para verificar a validade deste método para materiais de pavimentos brasileiros, desenvolveu-se um programa experimental no qual foram avaliadas propriedades mecânicas (resistência, rigidez e erodibilidade) e volumétricas (retração, absorção, expansão e ascensão capilar) de misturas constituídas por fresado asfáltico, brita graduada e cimento, variando-se a porcentagem de fresado (20% e 50%), o teor de cimento (2%, 4% e 6%), a energia de compactação (Intermediária e Modificada) e o tempo de cura dos corpos de prova (3, 7 e 14 dias). Os resultados dos ensaios mostraram que todas as variáveis analisadas afetam significativamente a resistência à compressão simples, a resistência à tração por compressão diametral e o módulo de resiliência das misturas, enquanto que a retração, a erodibilidade, a absorção, a expansão e a ascensão capilar são afetadas por algumas das variáveis independentes. Dentre outras conclusões, destaca-se que são obtidos elevados valores de resistência à compressão simples (1,61 MPa a 6,08 MPa), resistência à tração por compressão diametral (0,29 MPa a 1,00 MPa) e de módulo de resiliência (10390 MPa a 25719 MPa) com teores baixo (2%) e médio (4%) de cimento, sendo desnecessário e arriscado, pela elevada retração associada, o emprego de teor mais elevado (6%). Ainda, observou-se que o aumento da energia de compactação permite compensar a utilização de teores mais baixos de cimento no que se refere às resistências (à compressão, à tração e à erosão) e módulos obtidos. Globalmente, conclui-se que o método de dosagem de materiais estabilizados com cimento da Austroads (2002) pode ser usado como modelo para o desenvolvimento de um método de dosagem para reciclagem de pavimentos com adição de cimento, sendo necessárias pequenas complementações ou adaptações. O método de dosagem sugerido nesta Dissertação é, ao mesmo tempo, simples o suficiente para ser empregado em laboratórios de canteiros de obra e amplo o bastante para identificar as propriedades mecânicas e volumétricas que devem ser avaliadas ao elaborar-se um projeto de mistura reciclada com cimento. / Full-depth reclamation (FDR) with Portland cement is a technique used for structural and functional rehabilitation of pavements and has been used in Brazil for many years, especially because its technical, economical and environmental advantages. However, a larger diffusion of the technique has been inhibited by the lack of national standards and procedures, resulting in the adoption of different design criteria, which sometimes leads to a low efficiency of the FDR with cement. This research was carried out with the objective of setting the basis for a mix design method for FDR with cement, considering the Austroads (2002) mix design method for stabilized pavement materials as a model. In order to verify the applicability of the Austroads method to Brazilian pavement materials, an experimental program was carried out testing mechanical (strength, stiffness and durability) and volumetric (drying shrinkage, absorption, swell and capillary rise) properties of mixtures made of reclaimed asphalt pavement (RAP), graded crushed stone and cement. Specimens with different RAP contents (20% and 50%), cement contents (2%, 4% and 6%), compacted with two different efforts (Brazilian Intermediate and Modified) were cured for 3, 7 and 14 days. Test results showed that all the studied variables affect the unconfined compressive strength, indirect tensile strength and resilient modulus of the mixtures, while drying shrinkage, erodibility, absorption, swell and capillary rise are affected by some of the independent variables. Among other conclusions, it is pointed out that high values of unconfined compressive strength (1,61 MPa to 6,08 MPa), indirect tensile strength (0,29 MPa to 1,00 MPa) and resilient modulus (10390 MPa to 25719 MPa) may be achieved with low (2%) and intermediary (4%) cement contents, thus making the use of higher (6%) cement content unnecessary and unsafe, due to the higher costs and to the drying shrinkage associated. It was also observed that increases in the compaction effort may compensate the use of lower cement contents as regards to strengths and moduli obtained. Generally, can be concluded that the Austroads (2002) mix design method for stabilized pavement materials may be used as a model for the development of a mix design method for FDR with cement, being necessary only a few additions or adaptations. The suggested method is, simultaneously, simple enough to be used in field laboratories and comprehensive enough for including the mechanical and volumetric properties that must be evaluated when designing a mix for FDR with cement.

This thesis investigates the effect of added asphalt binder content on the performance and volumetric properties of asphalt concrete mixes containing Reclaimed Asphalt Pavement (RAP). Mixes with three different percentages of RAP (0%, 20%, 40%) obtained from an asphalt producer and three different percentages of asphalt binder (design asphalt content, design +0.5%, and design +1.0%) were evaluated. Additionally, a laboratory produced mix containing 100% RAP with four asphalt binder contents (0.0%, 0.5%, 1.0% and 1.5%) was also evaluated in order to determine the binder level that optimizes mix performance for the extreme case in RAP utilization. Performance of the mixtures was evaluated based on three criteria: stiffness (dynamic modulus), fatigue resistance (flexural beam), and rutting resistance (flow number). Results showed that a 0.5% increase in binder content improved both the fatigue and rutting resistance of the 0% and 20% RAP mixes with only slight decreases in dynamic modulus. However, the addition of various amounts of binder to the 40% RAP mix led to a significant decrease in rutting resistance with little or no improvement to fatigue resistance. Volumetric analysis was performed on all of the mixes to determine how the added binder content affected mix volumetric properties. Results of volumetric testing, specifically asphalt content and Voids in the Total Mix (VTM) at the design compaction effort, Ndesign, revealed that the 40% RAP mix incorporated a significantly higher level of binder during plant production which very likely contributed to the decrease in rutting resistance once additional binder was added in the laboratory. Additionally, the gyratory compaction effort that would result in 4 percent VTM at the optimal binder content over the three performance tests, N4%, was calculated for each mix. Results indicated that the VTM for the optimally performing 20% and 40% RAP mixes were well below current Virginia Department of transportation (VDOT) production standards. In addition, N4%, for the optimally performing 20% and 40% RAP mixes was 50% or less than the current design compaction effort of 65 gyrations. / Master of Science

La gomme d’Acacia est l’une des plus anciennes gommes naturelles dans le monde et la plus connue. Elle est définie comme l’exsudat gommeux produit par les arbres d’Acacia senegal et Acacia seyal. Les gommes d’Acacia sont composées d’arabinogalactanes protéines (AGPs), faiblement chargés, hyperbranchés avec une forte proportion de sucres (90%) et d’environ 1-3% de protéines et de minéraux. Malgré ses nombreuses applications industrielles, les connaissances sur ses propriétés volumétriques (hydrostatiques et hydrodynamiques) restent à améliorer. Ces propriétés peuvent être liées à la flexibilité et l’hydratation des molécules qui déterminent les propriétés fonctionnelles importantes comme les propriétés interfaciales. L'objectif de cette thèse est l’étude des propriétés volumétriques d’AGPs de la gomme d’Acacia. L’étude a été faite sur les principales variétés des gommes d’Acacia, A. senegal et A. seyal, ainsi que des fractions macromoléculaires d’A. senegal, obtenues par la chromatographie d'interaction hydrophobe et d'échange ionique. Les principaux résultats ont montré que les AGPs de gomme d’Acacia ont une structure semi flexible. De plus, des différences dans la flexibilité et l’hydratation entre les fractions d’AGPs ont été montré. Ces différences ont été expliquées par leurs différences en composition, polarité, masse molaire, forme et conformation. De plus, un comportement intermédiaire entre des protéines et des polysaccharides linéaires ont été montré. Finalement, un effet des agrégats d’AGPs sur les propriétés volumétriques a été mis en avance. / Acacia gum is the oldest and most widely known and used gum, it is a dried gummy exudate from the leaves and branches of the Acacia senegal and Acacia seyal trees. Acacia gums are weakly charged, amphiphilic hyperbranched arabinogalactan-proteins (AGPs). They are composed of about 90% polysaccharides and from 1-3% of proteins and minerals. In spite of the widely spread of industrial usage of A. gums, their volumetric properties (hydrostatic and hydrodynamic) have not been well studied. These properties have been linked to important properties such as flexibility and hydration of the molecule, which are related to important functional properties of A. gums (e. g. interfacial properties). The main objective of this PhD thesis was to study the volumetric properties of AGPs from Acacia gums exudates. For this effect, the main commercial species, A. senegal and A. seyal, and the macromolecular fractions of the former, obtained via hydrophobic interaction and ionic exchange chromatographies were studied. The main results showed that AGPs from Acacia gums have a semi-flexible structure. However, differences in their flexibility and hydration were seen among AGP fractions. These differences were explained based on their composition, polarity, molar mass, shape and conformation. Furthermore, an intermediate behavior between proteins and linear polysaccharides was evidenced. In addition, an effect of the presence of AGP based aggregates on the volumetric properties was seen.

O objetivo principal desta pesquisa é avaliar a influência que as propriedades estudadas dos agregados exercem sobre propriedades volumétricas e mecânicas de misturas asfálticas densas. Para tanto, foram avaliadas as propriedades de consenso e de origem, especificadas pelo Superpave, de um conjunto de agregados, além de suas densidades, porosidade, absorção e adesividade. Foram estudados agregados de gabro, basalto e areia natural e três tipos de granulometrias, uma denominada AZR, passando acima da zona de restrição da especificação Superpave, e outras duas, obtidas através do sistema de seleção granulométrica Bailey. Também três níveis de energia de compactação foram aplicados às misturas, 75, 110 e 155 golpes por face do corpo-de-prova Marshall. Avaliou-se o comportamento mecânico das misturas através dos ensaios de estabilidade e fluência Marshall, fluência por compressão uniaxial uniforme, fluência por compressão uniaxial dinâmica, resistência à tração, módulo de resiliência e fadiga. Os resultados mostraram que, de uma maneira geral, o agregado de gabro apresentou superioridade em relação ao agregado de basalto e de areia natural, tanto quando analisado isoladamente como quando analisado nas misturas asfálticas. Suas características de forma, angularidade e textura superficial permitiram arranjos entre partículas adequados, formando esqueletos estruturais resistentes à deformação permanente e também à fadiga. As análises das misturas à luz da granulometria mostram que, de uma maneira geral, a granulometria AZR produziu misturas mais estáveis, mais resistentes à deformação permanente e à fadiga. Pôde-se constatar, também, que as propriedades volumétricas são sensíveis às densidades dos agregados e à taxa de absorção destes, além de serem influenciadas diretamente pelas características de superfície dos agregados e pela energia de compactação. Com o aumento da energia de compactação aplicada, as partículas angulosas e rugosas dos agregados de gabro e de basalto arranjaram-se de maneira mais próxima e, por conseqüência, houve a diminuição dos vazios do agregado mineral e elevação da estabilidade e rigidez das misturas, sem, contudo, causar prejuízos à vida de fadiga. Os estudos sobre a absorção de asfalto pelos agregados revelaram que os agregados absorvem mais asfalto quanto mais fina a espessura da película de asfalto que os envolve e, também, que misturas com um mesmo teor de asfalto absorvem quantidades semelhantes de asfalto, sendo o tempo necessário para que a absorção se complete diretamente proporcional à viscosidade (temperatura) do asfalto. / The main objective of this research is to evaluate the influence that the studied properties of aggregates have on volumetric and mechanical characteristics of dense asphalt mixtures. It was evaluated origin and consensus properties, specified by the Superpave, for a set of aggregates, besides their densities, porosity, absorption and adhesiveness. Aggregates of gabbro, basalt and natural sand were studied and three types of aggregate gradations, one called AZR, passing above the zone of restriction of the Superpave specification, and two others, obtained through the Bailey method. Three levels of compaction energy were applied, corresponding respectively to 75, 110 and 155 blows of the Marshall hammer per face of the specimen. The mechanical behavior of the hot mix asphalt (HMA) was evaluated through the Marshall stability and flow, static and dynamic creep, indirect tensile strength, resilient modulus and fatigue tests. The results showed that, in general terms, the gabbro aggregate presented a superior behavior compared to the natural sand aggregate and the basalt aggregate, based on both aggregate and asphalt mixture evaluation tests. Its characteristics of form, angularity and surface texture resulted in an adequate arrangement between particles, building a resistant structural skeleton to both permanent deformation and fatigue cracking. Analyses of the HMA mixtures as a function of gradation showed that, in general terms, AZR mixtures were more stable, more resistant to permanent deformation and to fatigue cracking than Bailey mixtures. It could be evidenced that the volumetric properties depends on the specific gravity and the absorption rate of the aggregates, being also directly influenced by aggregate surface characteristics and compaction energy. Increasing the energy applied for specimen compaction resulted, for the angular and rough particles of gabbro and basalt aggregates, in a closer arrangement, with reduction of the voids in mineral aggregate and increase of the stability and stiffness of the mixtures, without, however, causing damages that could conduct to a shorter fatigue life. The studies about absorption of asphalt by aggregates showed that the smaller the asphalt film thickness the greater the asphalt absorption. The results also showed that HMA with the same asphalt content absorb similar amounts of asphalt, although the necessary time to complete the absorption is directly proportional to the asphalt viscosity (temperature).

O objetivo principal desta pesquisa é avaliar a influência que as propriedades estudadas dos agregados exercem sobre propriedades volumétricas e mecânicas de misturas asfálticas densas. Para tanto, foram avaliadas as propriedades de consenso e de origem, especificadas pelo Superpave, de um conjunto de agregados, além de suas densidades, porosidade, absorção e adesividade. Foram estudados agregados de gabro, basalto e areia natural e três tipos de granulometrias, uma denominada AZR, passando acima da zona de restrição da especificação Superpave, e outras duas, obtidas através do sistema de seleção granulométrica Bailey. Também três níveis de energia de compactação foram aplicados às misturas, 75, 110 e 155 golpes por face do corpo-de-prova Marshall. Avaliou-se o comportamento mecânico das misturas através dos ensaios de estabilidade e fluência Marshall, fluência por compressão uniaxial uniforme, fluência por compressão uniaxial dinâmica, resistência à tração, módulo de resiliência e fadiga. Os resultados mostraram que, de uma maneira geral, o agregado de gabro apresentou superioridade em relação ao agregado de basalto e de areia natural, tanto quando analisado isoladamente como quando analisado nas misturas asfálticas. Suas características de forma, angularidade e textura superficial permitiram arranjos entre partículas adequados, formando esqueletos estruturais resistentes à deformação permanente e também à fadiga. As análises das misturas à luz da granulometria mostram que, de uma maneira geral, a granulometria AZR produziu misturas mais estáveis, mais resistentes à deformação permanente e à fadiga. Pôde-se constatar, também, que as propriedades volumétricas são sensíveis às densidades dos agregados e à taxa de absorção destes, além de serem influenciadas diretamente pelas características de superfície dos agregados e pela energia de compactação. Com o aumento da energia de compactação aplicada, as partículas angulosas e rugosas dos agregados de gabro e de basalto arranjaram-se de maneira mais próxima e, por conseqüência, houve a diminuição dos vazios do agregado mineral e elevação da estabilidade e rigidez das misturas, sem, contudo, causar prejuízos à vida de fadiga. Os estudos sobre a absorção de asfalto pelos agregados revelaram que os agregados absorvem mais asfalto quanto mais fina a espessura da película de asfalto que os envolve e, também, que misturas com um mesmo teor de asfalto absorvem quantidades semelhantes de asfalto, sendo o tempo necessário para que a absorção se complete diretamente proporcional à viscosidade (temperatura) do asfalto. / The main objective of this research is to evaluate the influence that the studied properties of aggregates have on volumetric and mechanical characteristics of dense asphalt mixtures. It was evaluated origin and consensus properties, specified by the Superpave, for a set of aggregates, besides their densities, porosity, absorption and adhesiveness. Aggregates of gabbro, basalt and natural sand were studied and three types of aggregate gradations, one called AZR, passing above the zone of restriction of the Superpave specification, and two others, obtained through the Bailey method. Three levels of compaction energy were applied, corresponding respectively to 75, 110 and 155 blows of the Marshall hammer per face of the specimen. The mechanical behavior of the hot mix asphalt (HMA) was evaluated through the Marshall stability and flow, static and dynamic creep, indirect tensile strength, resilient modulus and fatigue tests. The results showed that, in general terms, the gabbro aggregate presented a superior behavior compared to the natural sand aggregate and the basalt aggregate, based on both aggregate and asphalt mixture evaluation tests. Its characteristics of form, angularity and surface texture resulted in an adequate arrangement between particles, building a resistant structural skeleton to both permanent deformation and fatigue cracking. Analyses of the HMA mixtures as a function of gradation showed that, in general terms, AZR mixtures were more stable, more resistant to permanent deformation and to fatigue cracking than Bailey mixtures. It could be evidenced that the volumetric properties depends on the specific gravity and the absorption rate of the aggregates, being also directly influenced by aggregate surface characteristics and compaction energy. Increasing the energy applied for specimen compaction resulted, for the angular and rough particles of gabbro and basalt aggregates, in a closer arrangement, with reduction of the voids in mineral aggregate and increase of the stability and stiffness of the mixtures, without, however, causing damages that could conduct to a shorter fatigue life. The studies about absorption of asphalt by aggregates showed that the smaller the asphalt film thickness the greater the asphalt absorption. The results also showed that HMA with the same asphalt content absorb similar amounts of asphalt, although the necessary time to complete the absorption is directly proportional to the asphalt viscosity (temperature).

<p>U ovoj doktorskoj disertaciji proučavano je građenje i termohromno&nbsp;pona&scaron;anje hloro kompleksa kobalt(II) jona u tri različita medijuma:&nbsp;amonijum-nitrat + <em>z</em>formamid (z= 2, 3, 4, 5, 6 i 20), amonijum-nitrat +&nbsp;<em>z</em>N-metilformamid (<em>z&nbsp;</em>= 3, 4, 5, 6 i 20) i amonijum-nitrat +&nbsp; <em>zN,N</em>-dimetilformamid (<em>z</em> = 3) u temperaturnom intervalu od 308,15 do&nbsp;348,15 K. Cilj ovog istraživanja je bio određivanje stabilnosti&nbsp;termohromnih kompleksa kobalta(II) koji se grade sahloridnim i&nbsp;nitratnim jonima i molekulima rastvarača, pronalaženje kvalitativne i&nbsp;kvantitativne zavisnosti konstanti stabilnosti kompleksa kobalta(II) od&nbsp;temperature i molskog odnosa komponenti ispitivanih sistema.&nbsp;Termodinamički parametri, koji karakteri&scaron;u reakcije asocijacije u&nbsp;ispitivanim sistemima izračunati su na osnovu dobijenih konstanti&nbsp;stabilnosti na različitim temperaturama. Drugi deo ovog rada obuhvata&nbsp;fizičko-hemijsku karakterizaciju ispitivanih sistema, i&nbsp; to: merenje&nbsp;gustine, provodljivosti i njihove viskoznosti. Na osnovu dobijenih&nbsp;podataka razmotrene su vrste interakcija koje se javljaju među&nbsp;česticama rastvarača i rastvorene supstance, kao i njihov uticaj na&nbsp;građenje kompleksnih&nbsp; čestica kobalta(II). Ispitivani sistemi su&nbsp;posebno interesantni, jer predstavljaju dobre medijume za ispitivanje&nbsp;termohromizma u praksi.</p> / <p>In this thesis absorption spectra of cobalt(II) chloride in three ammonium nitrate binary mixtures with organic solvents (formamide, N-methylformamide and&nbsp; <em>N,N</em>-dimethylformamide) at different temperatures (from 308.15 to 248.15 K) and compositions have been investigated in the wavelength range 400-800 nm. Influence of the temperature and composition of the mixture on complex formation between cobalt(II) and nitrate ions, chloride ions&nbsp; and/or solvent molecules have been studied. Thermodynamic parameters for cobalt(II)-ligand association in different solventswere also determined. The second part of this work involves physical-chemical characterization of the studied systems, namely: density, electrical conductivity and viscosity measurements. On the basis of the obtained&nbsp;data, the types and nature of the solute-solvent interactions that occur, as well as their impact on the cobalt(II) complex formation were discussed. In all investigated systems, complexes of cobalt(II) change the geometry and colour from pale pink to dark blueupon addition of &nbsp;chloride ions and upon heating/cooling. Hence, additional chemical energy can be stored in such system. Because the effective working temperatures match very well with that readily achievable under sunlight, these thermochromic systems present an &nbsp;example of novel materials suitable for auto-regulated protection and energy storage.</p>