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Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. Ben Wang, Florida State University, FAMU-FSU College of Engineering, Dept. of Industrial Engineering. Title and description from dissertation home page (Apr. 7, 2004). Includes bibliographical references.

In most industrialized countries, significant future activity in the construction sector will be related to repair and rehabilitation of aging infrastructure. This will require use of durable and high performance repair materials. Among various mechanisms cited for lack of durability in repairs, early-age shrinkage cracking in overlay materials is of utmost importance. Fiber-reinforcement can be used to alleviate some of the issues related to plastic shrinkage. However, quantifying the performance of cement-based composites under restrained shrinkage conditions remains an issue. Various test techniques are available to measure free and restrained shrinkage, but do not simulate the real constraint imposed by the substrate on the overlay. In this dissertation, an innovative test method called the bonded overlay technique is described. An overlay of fiber-reinforced material to be tested is cast directly on a substrate, and the entire assembly is subjected to controlled drying. Cracking in the overlay is then monitored and characterized. During the development of this test method, instrumentation was included to enable measurement of the crack propagation rate using image analysis, evaporation rate, heat development, and strain using embedded sensors. Using the above technique, the effect of mix proportion including variables such as water-cement ratio (w/c), sand-cement ratio (s/c), and coarse aggregate content were studied. An increase in w/c from 0.35 to 0.6 significantly increased the total cracking. Addition of coarse aggregates reduced shrinkage cracking, however, for the range of s/c investigated, no definite conclusions could be drawn. Mixes with 0-20% fly ash and a 7 lit/m3 dosage of shrinkage reducing admixtures indicated no significant reduction in cracking. The influence of fiber geometry on cracking in overlays was also investigated. Fiber types included different sizes of polypropylene and cellulose fibers and one type of glass fiber (volume fraction ranging between 0-0.4%). Glass fibers at a small dosage of 0.1% were the most efficient fiber and completely eliminated cracking. Of the two field projects considered: one was a plaza deck at the UBC Aquatic Center, where cellulose fibers were used, and the second at the UBC ChemBioE building, where polypropylene fibers were used in slabs-on-grade. Both overlays were instrumented with strain sensors, data from which were monitored over the Internet. Results clearly indicated that fibers reduced the strain development in fiber-reinforced overlays when compared to un-reinforced overlays. An energy-based fracture model was proposed to predict maximum crack widths and in a second study, an equation was proposed to correlate early-age shrinkage and flexural toughness of cellulose fibers. In both models, a reasonable correlation with the test data was observed. In addition, factorial design method was used and a mathematical model was proposed to correlate different variables such as w/c, s/c, and fiber dosage.

In most industrialized countries, significant future activity in the construction sector will be related to repair and rehabilitation of aging infrastructure. This will require use of durable and high performance repair materials. Among various mechanisms cited for lack of durability in repairs, early-age shrinkage cracking in overlay materials is of utmost importance. Fiber-reinforcement can be used to alleviate some of the issues related to plastic shrinkage. However, quantifying the performance of cement-based composites under restrained shrinkage conditions remains an issue. Various test techniques are available to measure free and restrained shrinkage, but do not simulate the real constraint imposed by the substrate on the overlay. In this dissertation, an innovative test method called the bonded overlay technique is described. An overlay of fiber-reinforced material to be tested is cast directly on a substrate, and the entire assembly is subjected to controlled drying. Cracking in the overlay is then monitored and characterized. During the development of this test method, instrumentation was included to enable measurement of the crack propagation rate using image analysis, evaporation rate, heat development, and strain using embedded sensors. Using the above technique, the effect of mix proportion including variables such as water-cement ratio (w/c), sand-cement ratio (s/c), and coarse aggregate content were studied. An increase in w/c from 0.35 to 0.6 significantly increased the total cracking. Addition of coarse aggregates reduced shrinkage cracking, however, for the range of s/c investigated, no definite conclusions could be drawn. Mixes with 0-20% fly ash and a 7 lit/m3 dosage of shrinkage reducing admixtures indicated no significant reduction in cracking. The influence of fiber geometry on cracking in overlays was also investigated. Fiber types included different sizes of polypropylene and cellulose fibers and one type of glass fiber (volume fraction ranging between 0-0.4%). Glass fibers at a small dosage of 0.1% were the most efficient fiber and completely eliminated cracking. Of the two field projects considered: one was a plaza deck at the UBC Aquatic Center, where cellulose fibers were used, and the second at the UBC ChemBioE building, where polypropylene fibers were used in slabs-on-grade. Both overlays were instrumented with strain sensors, data from which were monitored over the Internet. Results clearly indicated that fibers reduced the strain development in fiber-reinforced overlays when compared to un-reinforced overlays. An energy-based fracture model was proposed to predict maximum crack widths and in a second study, an equation was proposed to correlate early-age shrinkage and flexural toughness of cellulose fibers. In both models, a reasonable correlation with the test data was observed. In addition, factorial design method was used and a mathematical model was proposed to correlate different variables such as w/c, s/c, and fiber dosage.

In most industrialized countries, significant future activity in the construction sector will be related to repair and rehabilitation of aging infrastructure. This will require use of durable and high performance repair materials. Among various mechanisms cited for lack of durability in repairs, early-age shrinkage cracking in overlay materials is of utmost importance. Fiber-reinforcement can be used to alleviate some of the issues related to plastic shrinkage. However, quantifying the performance of cement-based composites under restrained shrinkage conditions remains an issue. Various test techniques are available to measure free and restrained shrinkage, but do not simulate the real constraint imposed by the substrate on the overlay. In this dissertation, an innovative test method called the bonded overlay technique is described. An overlay of fiber-reinforced material to be tested is cast directly on a substrate, and the entire assembly is subjected to controlled drying. Cracking in the overlay is then monitored and characterized. During the development of this test method, instrumentation was included to enable measurement of the crack propagation rate using image analysis, evaporation rate, heat development, and strain using embedded sensors. Using the above technique, the effect of mix proportion including variables such as water-cement ratio (w/c), sand-cement ratio (s/c), and coarse aggregate content were studied. An increase in w/c from 0.35 to 0.6 significantly increased the total cracking. Addition of coarse aggregates reduced shrinkage cracking, however, for the range of s/c investigated, no definite conclusions could be drawn. Mixes with 0-20% fly ash and a 7 lit/m3 dosage of shrinkage reducing admixtures indicated no significant reduction in cracking. The influence of fiber geometry on cracking in overlays was also investigated. Fiber types included different sizes of polypropylene and cellulose fibers and one type of glass fiber (volume fraction ranging between 0-0.4%). Glass fibers at a small dosage of 0.1% were the most efficient fiber and completely eliminated cracking. Of the two field projects considered: one was a plaza deck at the UBC Aquatic Center, where cellulose fibers were used, and the second at the UBC ChemBioE building, where polypropylene fibers were used in slabs-on-grade. Both overlays were instrumented with strain sensors, data from which were monitored over the Internet. Results clearly indicated that fibers reduced the strain development in fiber-reinforced overlays when compared to un-reinforced overlays. An energy-based fracture model was proposed to predict maximum crack widths and in a second study, an equation was proposed to correlate early-age shrinkage and flexural toughness of cellulose fibers. In both models, a reasonable correlation with the test data was observed. In addition, factorial design method was used and a mathematical model was proposed to correlate different variables such as w/c, s/c, and fiber dosage. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Sistemas multifásicos reativos, como as argamassas, vêm sendo bastante estudados e explorados das mais diversas formas ao longo dos anos. A mistura é uma das etapas do processamento (mistura, transporte e aplicação) desses sistemas que, devido à aparente simplicidade operacional tem sido de certa forma negligenciada. A qualidade da mistura exerce influência direta no comportamento reológico e nas propriedades no estado endurecido. Nesse contexto, os objetivos da pesquisa consistem em avaliar a influência de parâmetros que interferem no comportamento de mistura (tempo, taxa de adição de água e velocidade de mistura do equipamento), no intuito de entender o fenômeno físico envolvido, sugerindo técnicas de análise para estudá-los e propor procedimentos (sequência de introdução dos materiais) mais adequados para a mistura de argamassas em laboratório. O trabalho de pesquisa compreende duas etapas. A primeira trata da avaliação dos parâmetros que influenciam a mistura de argamassas (cimento, cal, filer e areia) com e sem aditivo dispersante (policarboxilato de sódio) e, estabelece técnicas de análise da curva de mistura, obtida no reômetro rotacional tipo planetário desenvolvido na POLI-USP. A segunda etapa estuda diferentes procedimentos de mistura de argamassas em laboratório, na Hobart, e os compara com o procedimento da ABNT NBR13276/2005. No estado fresco emprega-se a reometria rotacional (curva de mistura + ciclos de cisalhamento) e squeeze-flow (na segunda etapa do trabalho) para avaliação do comportamento reológico. No estado endurecido, as propriedades mecânicas são verificadas por meio de resistência à tração por compressão diametral, módulo de elasticidade dinâmico e porosidade. Os resultados obtidos na primeira etapa, indicam que a técnica empregada na análise das curvas mostra ser apropriada para avaliar o fenômeno físico envolvido na dispersão e homogeneização das partículas do sistema durante a mistura. Na segunda etapa, o estudo de diferentes procedimentos de mistura em laboratório, aponta que introduzir o líquido nos materiais sólidos, nas condições analisadas, tende a produzir sistemas mais fluidos. Dependendo da composição dos sistemas, estes podem ser mais ou menos suscetíveis ao processo de mistura. E, por fim, no estado endurecido, as propriedades avaliadas indicam que um processo de mistura adequado conduz a resultados satisfatórios no material endurecido, com redução da porosidade e melhor desempenho do produto final. / Multiphase reactive systems, such as mortars, have been extensively studied in many different ways over the years. The mixture is one of the processing steps (mixing, transport, application) of these systems that due to its apparent operational simplicity, has been somewhat neglected. The quality of the mixing process has a direct influence on the rheological behavior and on the properties in the hardened state. In this context, the objectives of the research are to assess the influence of experimental parameters that affect the mixing behavior (time, water addition rate and rotation speed) in order to understand the physical phenomena involved, and to develop analysis methodology and propose procedures (sequence of mixing) best suited for mixing mortar in the laboratory. The research comprises two steps; the first part is the evaluation of the influence of experimental parameters on mixing behavior of mortars (cement, lime, filler, sand) with and without additive (sodium polycarboxylate) and the establishment of a methodology to analyze the mixing curve obtained in planetary rotational rheometer developed on POLI-USP, and the second stage studies different procedures for mixing mortars in laboratory, on Hobart, and compares them with the current ABNT NBR13276/2005 standard procedure. In the fresh state rotational rheometer (mixing curve + shear cycles) and squeeze-flow (in the second stage of research) are used for rheological characterization, while mechanical properties were verified by splitting tensile strength, dynamic modulus of elasticity and porosity. The results obtained in the first step indicates that the technique employed for the analysis of the curves is suitable for evaluating the physical phenomena involved in the dispersion and homogenization of the particles during mixing. In the second step, the study of different mixing procedures in the laboratory indicates that introducing the water in the solids tends to produce more fluid systems. The mixing behavior of the systems depends on their mix design (composition). Finally, in the hardened state, properties evaluated indicated that a suitable mixing process leads to satisfactory results with reduced porosity and better final performance of the products.

La carbonatation est l’un des processus initiateurs de la corrosion des armatures du béton armé. Sa cinétique est souvent utilisée pour modéliser la durabilité des ouvrages. La carbonatation résulte de la réaction en présence d’eau entre le dioxyde de carbone contenu dans l’air et les phases hydratées de la pâte de ciment. Elle donne du carbonate de calcium et provoque une baisse du pH qui induit la dépassivation des armatures et leur corrosion. La carbonatation des matériaux à base de ciment a été largement étudiée ces dernières années mais les données de la littérature sont extrêmement contradictoires sur la plupart des évolutions qu’elle engendre tant au niveau microstructural qu’à l’échelle macroscopique. Notre travail a eu pour objectif d’étudier les conséquences microscopiques et macroscopiques de la carbonatation sur deux mortiers standards simples à base de ciment CEM I et CEM II. Nous avons mené une étude expérimentale approfondie sur deux mortiers normalisés à base de ciment CEM I et CEM II pour comprendre les mécanismes physico-chimiques de la carbonatation. Nous avons utilisé les techniques suivantes pour examiner les conséquences de la carbonatation sur les caractéristiques microstructurales de la matrice cimentaire : analyse thermogravimétrique, diffraction de rayons X, pycnométrie à l’hélium, adsorption – désorption d’azote et de vapeur d’eau. Comme ces modifications observées au niveau de la microstructure induisent à leur tour des évolutions significatives au niveau des propriétés macroscopiques d’usage et des indicateurs de durabilité, nous avons examiné les conséquences de la carbonatation sur la perméabilité au gaz, la vitesse de propagation des ondes ultrasonores, la conductivité thermique et la résistivité électrique de surface. Notre étude a également porté sur la contribution de la carbonatation à la cicatrisation des mortiers endommagés thermiquement. Enfin, nos résultats expérimentaux ont été utilisés comme base de données pour élaborer un modèle sur la propagation de CO2 dans la matrice cimentaire. / Carbonation is one of the most important factors that initiate the corrosion of steel bars in reinforced concrete. Its kinetics are often used to model the durability of structures. Under the action of carbon dioxide from the air and with the presence of water in the pores, several hydrated phases of the cement paste are carbonated and form calcium carbonate. This process causes a decrease in pH of the pore water, which subsequently induces the depassivation and corrosion of the rebars. Although the carbonation of cementitious materials has been extensively studied in recent years, results in literature about changes in both micro and macroscopic levels are extremely contradictory. The aim of this work is to study the micro and macroscopic effects of carbonation on two standard cement mortars CEM I and CEM II. A wide experimental campaign was conducted on two standard mortars CEM I and CEM II in order to apprehend the physicochemical mechanisms of the carbonation. The following techniques were used to examine the impacts of carbonation on the microstructural characteristics of the cementitious matrix : thermogravimetric analysis, X-ray diffraction, helium pycnometry, nitrogen and water vapor adsorption-desorption. As changes observed in the microstructure could consequently induce significant modifications in the macroscopic properties and the sustainability indicators, we examined the effects of carbonation on the gas permeability, the ultrasonic waves velocity, the thermal conductivity and electrical resistivity. Our work also studied the self-healing effect caused by carbonation of thermally damaged mortars. Finally, our experimental results were used as a database to elaborate a model of the propagation of CO2 in the cementitious matrix.

Sistemas multifásicos reativos, como as argamassas, vêm sendo bastante estudados e explorados das mais diversas formas ao longo dos anos. A mistura é uma das etapas do processamento (mistura, transporte e aplicação) desses sistemas que, devido à aparente simplicidade operacional tem sido de certa forma negligenciada. A qualidade da mistura exerce influência direta no comportamento reológico e nas propriedades no estado endurecido. Nesse contexto, os objetivos da pesquisa consistem em avaliar a influência de parâmetros que interferem no comportamento de mistura (tempo, taxa de adição de água e velocidade de mistura do equipamento), no intuito de entender o fenômeno físico envolvido, sugerindo técnicas de análise para estudá-los e propor procedimentos (sequência de introdução dos materiais) mais adequados para a mistura de argamassas em laboratório. O trabalho de pesquisa compreende duas etapas. A primeira trata da avaliação dos parâmetros que influenciam a mistura de argamassas (cimento, cal, filer e areia) com e sem aditivo dispersante (policarboxilato de sódio) e, estabelece técnicas de análise da curva de mistura, obtida no reômetro rotacional tipo planetário desenvolvido na POLI-USP. A segunda etapa estuda diferentes procedimentos de mistura de argamassas em laboratório, na Hobart, e os compara com o procedimento da ABNT NBR13276/2005. No estado fresco emprega-se a reometria rotacional (curva de mistura + ciclos de cisalhamento) e squeeze-flow (na segunda etapa do trabalho) para avaliação do comportamento reológico. No estado endurecido, as propriedades mecânicas são verificadas por meio de resistência à tração por compressão diametral, módulo de elasticidade dinâmico e porosidade. Os resultados obtidos na primeira etapa, indicam que a técnica empregada na análise das curvas mostra ser apropriada para avaliar o fenômeno físico envolvido na dispersão e homogeneização das partículas do sistema durante a mistura. Na segunda etapa, o estudo de diferentes procedimentos de mistura em laboratório, aponta que introduzir o líquido nos materiais sólidos, nas condições analisadas, tende a produzir sistemas mais fluidos. Dependendo da composição dos sistemas, estes podem ser mais ou menos suscetíveis ao processo de mistura. E, por fim, no estado endurecido, as propriedades avaliadas indicam que um processo de mistura adequado conduz a resultados satisfatórios no material endurecido, com redução da porosidade e melhor desempenho do produto final. / Multiphase reactive systems, such as mortars, have been extensively studied in many different ways over the years. The mixture is one of the processing steps (mixing, transport, application) of these systems that due to its apparent operational simplicity, has been somewhat neglected. The quality of the mixing process has a direct influence on the rheological behavior and on the properties in the hardened state. In this context, the objectives of the research are to assess the influence of experimental parameters that affect the mixing behavior (time, water addition rate and rotation speed) in order to understand the physical phenomena involved, and to develop analysis methodology and propose procedures (sequence of mixing) best suited for mixing mortar in the laboratory. The research comprises two steps; the first part is the evaluation of the influence of experimental parameters on mixing behavior of mortars (cement, lime, filler, sand) with and without additive (sodium polycarboxylate) and the establishment of a methodology to analyze the mixing curve obtained in planetary rotational rheometer developed on POLI-USP, and the second stage studies different procedures for mixing mortars in laboratory, on Hobart, and compares them with the current ABNT NBR13276/2005 standard procedure. In the fresh state rotational rheometer (mixing curve + shear cycles) and squeeze-flow (in the second stage of research) are used for rheological characterization, while mechanical properties were verified by splitting tensile strength, dynamic modulus of elasticity and porosity. The results obtained in the first step indicates that the technique employed for the analysis of the curves is suitable for evaluating the physical phenomena involved in the dispersion and homogenization of the particles during mixing. In the second step, the study of different mixing procedures in the laboratory indicates that introducing the water in the solids tends to produce more fluid systems. The mixing behavior of the systems depends on their mix design (composition). Finally, in the hardened state, properties evaluated indicated that a suitable mixing process leads to satisfactory results with reduced porosity and better final performance of the products.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A utilizaÃÃo de resÃduos como materiais alternativos tem se mostrado uma soluÃÃo satisfatÃria de acordo com vÃrias pesquisas realizadas. Os produtos da combustÃo do carvÃo mineral (PCCs) sÃo resÃduos que causam impacto ambiental, mas apresentam grande potencial de utilizaÃÃo no setor da construÃÃo civil na produÃÃo de argamassas e concretos. Apresentam elevado teor de sÃlica (SiO2), podendo ser utilizados como pozolanas. Esta pesquisa objetivou verificar a viabilidade da utilizaÃÃo dos produtos da combustÃo do carvÃo mineral em argamassas de assentamento e revestimento. As matÃrias-primas foram caracterizadas quanto aos aspectos fÃsicos, quÃmicos e para os PCCs tambÃm foi avaliada sua pozolanicidade. Foram confeccionadas argamassas de referÃncia e com adiÃÃo de PCCs nos teores de 10, 20, 30, 40 e 50% como substituto parcial do cimento. ApÃs tempos de cura de 7 e 28 dias, foram feitos teste de resistÃncia à traÃÃo na flexÃo e resistÃncia à compressÃo. AlÃm disso, as argamassas foram sujeitas a anÃlises de difraÃÃo de Raios â X, Microscopia EletrÃnica de Varredura, absorÃÃo de Ãgua, determinaÃÃo de Ãndice de vazios e massa especÃfica aparente. Os resultados obtidos mostraram-se compatÃveis quando comparados com os dados da literatura, demonstrando ser viÃvel a aplicaÃÃo dos produtos da combustÃo do carvÃo mineral na indÃstria da construÃÃo civil. / The use of residues as alternative materials has proven successful according to several investigations. Coal combustion products (CCPs) is a residue that causes environmental impact, but it has a great potential for use in civil engineering construction in the production of mortars and concrete. It posesses a high content of silica (SiO2) and so it can be used as pozzolan. This research aimed to verify the viability of adding coal combustion products to mortars for bricklaying and covering. The raw materials were submitted to physical, and chemical characterization. CCPs were also rated according to their pozzolanicity. Reference mortars were prepared, as well as mortars containing 10, 20, 30, 40 and 50% amounts of CCPs as a partial replacement for cement. After curing time of 7 and 28 days, prismatic samples were tested to determine their tensile strength in bending and their compression strength. Moreover, the mortars were subjected to X-ray diffraction, scanning electron microscopy and determination of water absorption, voids and apparent density. The results obtained were consistent with literature data, showing that application of coal combustion products in the construction industry is a viable alternative.

This Master thesis is focused on characterization of multicompound self-compacting heavy-weight mortars resistant against long lasting influence of ionizing radiation in the underground nuclear waste storage. It examines a specific combination of properties of heavy-weight concretes and self-compacting mortars while considering the ecological and energetic impact of their production, as well as the productibility of partial substitutions that do not have negative impact on material properties. The Experimental part provides a comprehensive overview of composition and properties of self-compacting heavy-weight mortars with varying percentages of cement-to-mortar ratio. Sample properties were evaluated based on mechanical test results, thermal analysis, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction.