Three sets of concrete blocks were cast to investigate the effects of natural exposure conditions, at the macro and microclimate scale, and field curing on the performance and durability of OPC and OPCjGGBS concretes. These are termed the Loughborough winter series, the Loughborough summer series and the Muscat summer series. Three concrete mixes were investigated in the two Loughborough series (30 and 50 MPa OPC concrete mixes and a 30 MPa OPCjGGBS concrete mix) and two in the Muscat weather series (the two 30 MPa concretes). A group of specimens were cast with each mix consisting of 600 x 500 x 150mm concrete blocks plus control cubes and prisms. The samples were cured in-situ and exposed to a range of curing methods and microclimates. Surface zone properties (up to 50mm depth) were evaluated by air permeability, sorptivity, carbonation, thermogravimetry (TG) and mercury intrusion porosimetry (MIP) tests, conducted after 3 and 12 months of site exposure. The results revealed distinct variations due to macroclimate, microclimate, curing, concrete type and age. The air permeability, sorptivity and carbonation of the concrete exposed under moderate and rainy conditions of a Loughborough summer season were lower than identical concrete cast and cured during a very cold and dry Loughborough winter season. Further, the sorptivity of concrete subjected to the hot and dry climatic conditions of Muscat was significantly higher than companion samples subjected to the temperate Loughborough climate. Significant variations in properties were observed within the two sides of the same concrete element, each subjected to a different microclimate. The air permeability, sorptivity, carbonation and porosity were reduced with increased hessian curing duration. However, premature drying of wet hessian during curing had an adverse effect on concrete quality as this produced concrete of higher permeability and carbonation than non-cured concrete. The application of controlled permeability formwork was effective in improving the concrete's sub-surface properties. The curing affected zone (CAZ) extended to approximately 20mm below the surface of the concrete that was exposed to the Loughborough winter and summer climate, and 40-50mm for the concrete exposed to the Muscat climate, with notable variation in properties due to climate and curing. The TG and MlP results provided insights into the mechanisms associated with the variations in the three concrete's properties due to natural field exposure.

Electrical conductivity (or resistivity) of cementitious materials is considered to be a fundamental property and is commonly measured using nondestructive and noninvasive testing techniques. Therefore, electrical measurements are gaining popularity in both research and field applications for structural health monitoring and material characterization of civil engineering infrastructure systems. Based on the results of measurements, the engineer can schedule maintenance more accurately and give an early warning of possible structural failure. Recently, health monitoring systems are capable of significantly increasing the cost efficiency of maintenance and repair by helping engineers improve the safety and maintainability of structures through early damage detection. The research team at the University of Texas at Austin developed a low-cost, passive, wireless conductivity sensor system. Sensors are wirelessly interrogated using external reader during inspection over the service life of the structure to monitor the conductivity variations within concrete. The focus of this work is to assess the condition of cementitious materials by measuring electrical conductivity using passive wireless sensors. By analyzing the measured conductivity data, the condition of the cementitious material, such as extent of hydration, setting and hardening times, and transport phenomena, can be assessed. This document also provides comprehensive information on the design, fabrication, interrogation, and response of conductivity sensor platforms. / text

O maior uso do concreto de alta resistência, o uso de desmoldante e/ou o emprego de fôrmas plastificadas são fatores que cada vez mais contribuem para a superfície do concreto tornar-se lisa e de baixa porosidade superficial. Dessa forma, há prejuízo da absorção capilar que deve existir na camada superficial da base, de modo a permitir a penetração e a ancoragem dos produtos de hidratação da argamassa de revestimento no interior do substrato, garantindo a ancoragem mecânica. Neste sentido, a presente dissertação é resultado de um trabalho experimental realizado para investigar a influência da rugosidade gerada pelos tratamentos superficiais realizados nos substratos de concreto, com ou sem desmoldante, tais como lavagem por hidrojateamento, escovação, lixamento, apicoamento e uso de retardador de pega de superfície, na aderência do revestimento de argamassa. Para atender os objetivos propostos, moldaram-se prismas de concreto em três níveis de resistência fc28 (25 MPa, 35 MPa e 45 MPa), cujas superfícies foram tratadas e preparadas com chapisco convencional, traço 1:3 e chapisco adesivo. A argamassa de revestimento empregada foi industrializada. O programa experimental envolveu primeiramente a caracterização inicial dos materiais utilizados na confecção dos prismas de concreto, bem como das argamassas empregadas. Como caracterização dos substratos tratados, foram realizados ensaios para caracterizar a superfície, quanto à rugosidade e sucção capilar. A rugosidade foi avaliada em duas dimensões, através de perfis, de acordo com parâmetros normalizados, e também em três dimensões, através da superfície específica. Após o tratamento dos substratos, foi feita a aplicação da camada de chapisco, convencional e industrializado, e posteriormente, a aplicação da argamassa de revestimento, em camada única. Por fim, os revestimentos aplicados foram avaliados quanto à resistência de aderência e extensão de aderência. Com os resultados obtidos, concluiu-se que o uso do desmoldante prejudica a sucção capilar de substratos de concreto de fc28 igual ou inferior a 35 MPa. Conclui-se também que concretos de fc28 igual a 25 MPa possuem porosidade suficiente para garantir ancoragem mecânica, não necessitando de tratamento superficial, assim como quando se utiliza chapisco industrializado em qualquer concreto. Ao se utilizar chapisco convencional, a resistência de aderência aumenta a medida que se aumenta a rugosidade da superfície. / The widespread use of high resistance concrete , the use of lubricant and the employment of plastic-coated molds are factors that more and more contribute to the flat surface and low porosity of the concrete. Thus, there is damage of the capillary absorption that should exist in the substrate superficial layer, in order to allow the entrance and the anchorage of the hydration products of the coating mortar inside the substrate, guaranteeing the mechanical anchorage. In this way, the present dissertation resulted as experimental work realized to investigate the influence of the rugosity generated by the superficial treatments in the concrete substrate, with or without lubricant, such as wash with high pressure water jetting, brushing, grinding, milling and use of retarder of surface, in the adherence of the coating mortars. To reach the proposed objectives, concrete prisms were molded in three levels of resistance fc28 (25 MPa, 35 MPa and 45MPa), its surfaces were treated and prepared with conventional slurry mortar and adhesive slurry mortar. The coating mortar was industrialized. The experimental program involved the initial characterization of the materials used in concrete and mortars. To characterize the concrete surface tests were realized to characterize the rugosity and sorptivity. The rugosity was evaluated in two dimensions, through profiles, in accordance with parameters normalized, and also in three dimensions, through specific surface. Slurry mortar industrialized and conventional was applied after the substrate treatment, and the covering mortar was applied after in only one layer. Finally, the coverings applied were evaluated on the bond strength and adherence extension. The results obtained showed us that the use of the lubricant damages capillary suction on the concrete substrate 35MPa. Concretes 25MPa possess enough porosity to guarantee mechanical anchorage, not needing superficial treatment, as well when slurry mortar industrialized is used in any concrete. The resistance of adherence increases when the rugosity of the surface increases.

O maior uso do concreto de alta resistência, o uso de desmoldante e/ou o emprego de fôrmas plastificadas são fatores que cada vez mais contribuem para a superfície do concreto tornar-se lisa e de baixa porosidade superficial. Dessa forma, há prejuízo da absorção capilar que deve existir na camada superficial da base, de modo a permitir a penetração e a ancoragem dos produtos de hidratação da argamassa de revestimento no interior do substrato, garantindo a ancoragem mecânica. Neste sentido, a presente dissertação é resultado de um trabalho experimental realizado para investigar a influência da rugosidade gerada pelos tratamentos superficiais realizados nos substratos de concreto, com ou sem desmoldante, tais como lavagem por hidrojateamento, escovação, lixamento, apicoamento e uso de retardador de pega de superfície, na aderência do revestimento de argamassa. Para atender os objetivos propostos, moldaram-se prismas de concreto em três níveis de resistência fc28 (25 MPa, 35 MPa e 45 MPa), cujas superfícies foram tratadas e preparadas com chapisco convencional, traço 1:3 e chapisco adesivo. A argamassa de revestimento empregada foi industrializada. O programa experimental envolveu primeiramente a caracterização inicial dos materiais utilizados na confecção dos prismas de concreto, bem como das argamassas empregadas. Como caracterização dos substratos tratados, foram realizados ensaios para caracterizar a superfície, quanto à rugosidade e sucção capilar. A rugosidade foi avaliada em duas dimensões, através de perfis, de acordo com parâmetros normalizados, e também em três dimensões, através da superfície específica. Após o tratamento dos substratos, foi feita a aplicação da camada de chapisco, convencional e industrializado, e posteriormente, a aplicação da argamassa de revestimento, em camada única. Por fim, os revestimentos aplicados foram avaliados quanto à resistência de aderência e extensão de aderência. Com os resultados obtidos, concluiu-se que o uso do desmoldante prejudica a sucção capilar de substratos de concreto de fc28 igual ou inferior a 35 MPa. Conclui-se também que concretos de fc28 igual a 25 MPa possuem porosidade suficiente para garantir ancoragem mecânica, não necessitando de tratamento superficial, assim como quando se utiliza chapisco industrializado em qualquer concreto. Ao se utilizar chapisco convencional, a resistência de aderência aumenta a medida que se aumenta a rugosidade da superfície. / The widespread use of high resistance concrete , the use of lubricant and the employment of plastic-coated molds are factors that more and more contribute to the flat surface and low porosity of the concrete. Thus, there is damage of the capillary absorption that should exist in the substrate superficial layer, in order to allow the entrance and the anchorage of the hydration products of the coating mortar inside the substrate, guaranteeing the mechanical anchorage. In this way, the present dissertation resulted as experimental work realized to investigate the influence of the rugosity generated by the superficial treatments in the concrete substrate, with or without lubricant, such as wash with high pressure water jetting, brushing, grinding, milling and use of retarder of surface, in the adherence of the coating mortars. To reach the proposed objectives, concrete prisms were molded in three levels of resistance fc28 (25 MPa, 35 MPa and 45MPa), its surfaces were treated and prepared with conventional slurry mortar and adhesive slurry mortar. The coating mortar was industrialized. The experimental program involved the initial characterization of the materials used in concrete and mortars. To characterize the concrete surface tests were realized to characterize the rugosity and sorptivity. The rugosity was evaluated in two dimensions, through profiles, in accordance with parameters normalized, and also in three dimensions, through specific surface. Slurry mortar industrialized and conventional was applied after the substrate treatment, and the covering mortar was applied after in only one layer. Finally, the coverings applied were evaluated on the bond strength and adherence extension. The results obtained showed us that the use of the lubricant damages capillary suction on the concrete substrate 35MPa. Concretes 25MPa possess enough porosity to guarantee mechanical anchorage, not needing superficial treatment, as well when slurry mortar industrialized is used in any concrete. The resistance of adherence increases when the rugosity of the surface increases.

O maior uso do concreto de alta resistência, o uso de desmoldante e/ou o emprego de fôrmas plastificadas são fatores que cada vez mais contribuem para a superfície do concreto tornar-se lisa e de baixa porosidade superficial. Dessa forma, há prejuízo da absorção capilar que deve existir na camada superficial da base, de modo a permitir a penetração e a ancoragem dos produtos de hidratação da argamassa de revestimento no interior do substrato, garantindo a ancoragem mecânica. Neste sentido, a presente dissertação é resultado de um trabalho experimental realizado para investigar a influência da rugosidade gerada pelos tratamentos superficiais realizados nos substratos de concreto, com ou sem desmoldante, tais como lavagem por hidrojateamento, escovação, lixamento, apicoamento e uso de retardador de pega de superfície, na aderência do revestimento de argamassa. Para atender os objetivos propostos, moldaram-se prismas de concreto em três níveis de resistência fc28 (25 MPa, 35 MPa e 45 MPa), cujas superfícies foram tratadas e preparadas com chapisco convencional, traço 1:3 e chapisco adesivo. A argamassa de revestimento empregada foi industrializada. O programa experimental envolveu primeiramente a caracterização inicial dos materiais utilizados na confecção dos prismas de concreto, bem como das argamassas empregadas. Como caracterização dos substratos tratados, foram realizados ensaios para caracterizar a superfície, quanto à rugosidade e sucção capilar. A rugosidade foi avaliada em duas dimensões, através de perfis, de acordo com parâmetros normalizados, e também em três dimensões, através da superfície específica. Após o tratamento dos substratos, foi feita a aplicação da camada de chapisco, convencional e industrializado, e posteriormente, a aplicação da argamassa de revestimento, em camada única. Por fim, os revestimentos aplicados foram avaliados quanto à resistência de aderência e extensão de aderência. Com os resultados obtidos, concluiu-se que o uso do desmoldante prejudica a sucção capilar de substratos de concreto de fc28 igual ou inferior a 35 MPa. Conclui-se também que concretos de fc28 igual a 25 MPa possuem porosidade suficiente para garantir ancoragem mecânica, não necessitando de tratamento superficial, assim como quando se utiliza chapisco industrializado em qualquer concreto. Ao se utilizar chapisco convencional, a resistência de aderência aumenta a medida que se aumenta a rugosidade da superfície. / The widespread use of high resistance concrete , the use of lubricant and the employment of plastic-coated molds are factors that more and more contribute to the flat surface and low porosity of the concrete. Thus, there is damage of the capillary absorption that should exist in the substrate superficial layer, in order to allow the entrance and the anchorage of the hydration products of the coating mortar inside the substrate, guaranteeing the mechanical anchorage. In this way, the present dissertation resulted as experimental work realized to investigate the influence of the rugosity generated by the superficial treatments in the concrete substrate, with or without lubricant, such as wash with high pressure water jetting, brushing, grinding, milling and use of retarder of surface, in the adherence of the coating mortars. To reach the proposed objectives, concrete prisms were molded in three levels of resistance fc28 (25 MPa, 35 MPa and 45MPa), its surfaces were treated and prepared with conventional slurry mortar and adhesive slurry mortar. The coating mortar was industrialized. The experimental program involved the initial characterization of the materials used in concrete and mortars. To characterize the concrete surface tests were realized to characterize the rugosity and sorptivity. The rugosity was evaluated in two dimensions, through profiles, in accordance with parameters normalized, and also in three dimensions, through specific surface. Slurry mortar industrialized and conventional was applied after the substrate treatment, and the covering mortar was applied after in only one layer. Finally, the coverings applied were evaluated on the bond strength and adherence extension. The results obtained showed us that the use of the lubricant damages capillary suction on the concrete substrate 35MPa. Concretes 25MPa possess enough porosity to guarantee mechanical anchorage, not needing superficial treatment, as well when slurry mortar industrialized is used in any concrete. The resistance of adherence increases when the rugosity of the surface increases.

Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.

Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.

Many Ministry of Transportation of Ontario (MTO) projects consist of construction and maintenance of reinforced concrete structures. Where appropriate test methods exist, MTO has been moving towards use of performance-based specifications for durability control of concrete. MTO currently uses ASTM C1202 (RCPT) coulomb values to assess concrete durability. This test requires taking cores, so replacing this test with a faster non-destructive technique is important. The main focus of this program was to study the Wenner probe surface resistivity as a non-destructive test device and evaluate the potential for replacement of RCPT with the Wenner resistivity. This research program consists of the determination of RCPT values, water sorptivity coefficients and electrical resistivities (bulk and surface) of nine concrete mixtures. In addition, the development of the Wenner probe instrument was studied. As well, correlations between resistivity and ASTM C1202 and C1585 are provided followed by technical recommendations for improving the Wenner test.

Many Ministry of Transportation of Ontario (MTO) projects consist of construction and maintenance of reinforced concrete structures. Where appropriate test methods exist, MTO has been moving towards use of performance-based specifications for durability control of concrete. MTO currently uses ASTM C1202 (RCPT) coulomb values to assess concrete durability. This test requires taking cores, so replacing this test with a faster non-destructive technique is important. The main focus of this program was to study the Wenner probe surface resistivity as a non-destructive test device and evaluate the potential for replacement of RCPT with the Wenner resistivity. This research program consists of the determination of RCPT values, water sorptivity coefficients and electrical resistivities (bulk and surface) of nine concrete mixtures. In addition, the development of the Wenner probe instrument was studied. As well, correlations between resistivity and ASTM C1202 and C1585 are provided followed by technical recommendations for improving the Wenner test.

Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.