This thesis presents two separate applications of ionising radiation in Civil Engineering. The first is an investigation to determine the cement content of concrete using gamma-rays from the naturally occurring isotopes 238U, 232Th and their decay chains as well as 40K. Two sets of equations are derived and discussed. Spectra from cement, aggregate and concrete samples were made and the useful full energy peaks from the above sources identified. Two concrete samples were prepared using the same cement, but, containing two different aggregates: a granite based aggregate and a flint based aggregate. A third concrete sample was then prepared where the cement content was not initially known. Data from the first two tests was then used to determine the mass of cement used in the blind test. A great deal of valuable information has also been accrued concerning the interaction of statistical errors in the equations for the prediction of cement content. Spectra from four different cements were collected at regular intervals over a 24 month period and the variation in the activity of each cement over this period is discussed. The second section of this work presents an imaging technique that uses pair production annihilation photons to examine the state of steel reinforcement in concrete structures. Computer simulations along with experimental work have been used. The experimental work used a 226Ra needle as a photon source as it provided a range of gamma-rays with energies over the pair production threshold of 1022keV. A 31mm rebar with 30mm of concrete cover was successfully located during the experimental work. The data collected from the computer simulations has shown that the geometry and the material between the photon source, rebar and detector is of great importance.

Pressure is mounting in the construction industry to adopt more environmentally sustainable methods to reduce CO2 emissions. Portland cement (PC) often constitutes to more than two-thirds of the embodied energy of concrete, and its production generates 5% of global greenhouse gas emissions. One efficient strategy to reduce the cement content without sacrificing performance is the use of particle packing models (PPM) to mix- proportion concrete mixtures with low cement content, the so-called low cement content (LCC) concrete. If on the one hand LCC was seen to be an effective sustainable alternative to the construction industry, its mechanical behaviour, durability and long-term performance are still under debate and thus further research is needed in the area. In this project, continuous PPM theories were used to mix- design structural concrete mixes presenting distinct mechanical properties (i.e. 25 & 35 MPa) and cement contents. Their performance was evaluated in the fresh and hardened states, and gaps, recommendations, and further needs were highlighted. Results show that the use of PPM enables the development of LCC systems, showing impressive hardened state performance (i.e. higher compressive strength and modulus of elasticity and lower electrical resistivity) and low carbon footprint. However, challenges in the fresh state were faced, which may be potentially solved with the use of chemical admixtures, fillers and/or supplementary cementing materials (SCMs).

Master of Science / Department of Civil Engineering / Mustaque A. Hossain / Based on a 2017 report on infrastructure by the American Society of Civil Engineers, 13% of Kansas public roads are in poor condition. Furthermore, reconstruction of a two-lane concrete pavement costs between $0.8 and $1.15 million dollars per lane mile. High early strength Portland cement concrete pavement (PCCP) patches are widely used in pavement preservation in Kansas due to the ability to open to traffic early. However, these repairs done by the Kansas Department of Transportation (KDOT) deteriorate faster than expected, though, prompting a need for inexpensive, durable high early strength concrete repair mixtures that meet KDOT standards (i.e., a 20-year service life). This study developed an experimental matrix consisting of six PCCP patching mixture designs with varying cement content and calcium chloride dosage. The mixtures were subjected to isothermal calorimetry, strength testing, drying shrinkage, and various durability tests. The effects of cement content and calcium chloride dosage on concrete strength and durability were then investigated. In addition, the compressive strength development with time, the split tensile versus compressive strength relationship, and the shrinkage strain of the PCCP patching mixtures were compared to established relationships provided by the American Concrete Institute (ACI). Results showed a maximum 3% increase in total heat generated by various concrete paste samples in isothermal calorimetry testing. The minimum compressive strength of 1,800 psi required by KDOT could likely be obtained using any of the PCCP mixtures, regardless of the cement content or calcium chloride dosage used in the study. Furthermore, surface resistivity tests for mixtures containing calcium chloride could result in erroneous measurements. Only one mixture satisfied the maximum expansion and minimum relative dynamic modulus of elasticity required by KDOT. Some ACI relationships for shrinkage and strength development do not appear to be valid for high early strength PCCP patching mixtures.

Concrete in Sweden has traditionally been manufactured with natural aggregate from glaciofluvial eskers. There is a need to preserve the remaining eskers because of their cultural value and importance for water filtration, thus natural aggregate has to be replaced. The most realistic alternative is to use crushed rocks. The major problem with crushed rocks in concrete production is the workability. This is because crushed rocks have less favorable properties. The fragments are flakier and have a rougher surface than natural aggregates that have been rounded in water. Without any amelioration of the crushed rock, to reach a certain workability and strength, the amount of cement in the mix has to be increased. Cement production requires large amounts of energy and the decarbonation of limestone releases large amounts of CO2. Combined, the release of CO2, due to burning and decarbonation of limestone, accounts for about 5% of the global CO2 emissions. An increase in cement consumptions is less desirable. Thus to replace natural aggregates, the use of crushed rocks has to be optimized as regard cement consumption. Several crushed aggregates, most from granitic rocks, from all over Sweden were analysed in this study. These crushed rocks were characterized according to their grading, specific surface, shape and petrography and compared to natural sand. Rheological tests that reveals the workability in detail was performed on mortars. The tests showed that as regard workability the 0-2 mm fraction is the most important factor. Further, the maximum aggregate size was gradually increased up to 16 mm, to have a more realistic approach to the concrete produced by the building industry. The results showed that with grading optimization and superplasticizer, some crushed rocks can be used for concrete production without increasing, and even decreasing, the cement consumption. This research also contemplated the use of filler. As a mineral admixture it can improve the compressive strength. It can also be used to replace cement; a replacement up to 20 kg/m3 of cement by filler can be done without significant effect on compressive strength.

A adoção de técnicas de melhoramento de solos é prática cada vez mais recorrente em obras geotécnicas, contudo, os critérios de dosagem e parâmetros de previsão do comportamento desses solos parecem não acompanhar a evolução tecnológica das referidas técnicas. O parâmetro de estado para areias (ψ) não consegue representar o comportamento de areias artificialmente cimentadas, por levar em consideração apenas a influência do índice de vazios e do estado de tensões. Propõe-se, neste estudo, instituir o índice porosidade/teor volumétrico de cimento (η/Civ) como um parâmetro de estado para areias artificialmente cimentadas, por ser um critério racional que relaciona a porosidade da mistura compactada com o teor volumétrico de cimento adicionado. A partir da utilização desse parâmetro, é possível calibrar a quantidade de cimento e a energia de compactação utilizada, a fim de proporcionar uma mistura que atenda aos requisitos de projeto e que seja viável de executar em obra com os recursos materiais e financeiros disponíveis. O programa experimental compreendeu a realização de 17 ensaios triaxiais, drenados e não drenados, analisados em conjunto com resultados já obtidos em estudos anteriores. Análises do comportamento tensão-deformação, variação volumétrica-deformação axial, geração de poropressão, trajetórias de tensões drenadas e não drenadas, envoltórias de resistência, comportamento tensão-dilatância, da aplicação da teoria do estado crítico e uma breve análise estatística embasaram a comprovação de que o parâmetro η/Civ é adequado para previsão do comportamento de corpos de prova de areia artificialmente cimentados. / The adoption of soil improvement techniques is becoming more frequent in geotechnical works, however, the dosage criteria and the parameters used to predict the soil behavior do not seem to follow the technological evolution of these techniques. The state parameter for sands (ψ) cannot represent the behavior of artificially cemented sands because it considers only the influence of the void ratio and the stress state. It is proposed to establish the porosity/volumetric content of cement (η/Civ) as a state parameter for artificially cemented sands, since it is a rational criterion which relates the porosity of the compacted mixture to the volumetric content of cement added. By using this parameter, it is possible to calibrate the amount of cement and the compaction energy used in order to provide a mixture that meets the design requirements and that is feasible to perform on site construction with the material and financial resources available there. The experimental program included the realization of 17 triaxial testes, performed in the drained and undrained conditions, analyzed simultaneously with other results obtained from previous studies. Analysis of stress-strain behavior, volumetric variation-axial strain, pore pressure development, drained and non-drained stress paths, resistance envelope, stress-dilatation behavior, the application of the critical state theory, and a brief statistical analysis supported that the η/Civ parameter is suitable for predicting the behavior of artificially cemented sand specimens.

Concrete, the major construction material used in the civil industry worldwide, displays remarkable performance and economic benefits. Yet, it also presents a huge environmental impact producing about 7% of the global carbon dioxide (CO2). Given the rise of global warming concerns, studies have been focusing on alternatives to reduce the amount of Portland cement (PC), which is the least sustainable ingredient of the mixture, for example by adopting particle packing model (PPM) techniques. Although a promising alternative, there is currently a lack of studies regarding the efficiently use of PPMs to reduce PC without compromising the fresh and hardened properties of the material. This work appraises the influence of PPMs and advanced mix-design techniques on the fresh (rheological behaviour) and hardened (compressive strength, modulus of elasticity, porosity, and permeability) state behaviours of systems with reduced amount of PC, the so-called low cement content (LCC) concrete. Results show that is possible to produce eco-efficient concrete maintaining and/or enhancing fresh and hardened properties of the material. Nevertheless, further durability and long-term behaviour must be performed on LCC systems.

A adoção de técnicas de melhoramento de solos é prática cada vez mais recorrente em obras geotécnicas, contudo, os critérios de dosagem e parâmetros de previsão do comportamento desses solos parecem não acompanhar a evolução tecnológica das referidas técnicas. O parâmetro de estado para areias (ψ) não consegue representar o comportamento de areias artificialmente cimentadas, por levar em consideração apenas a influência do índice de vazios e do estado de tensões. Propõe-se, neste estudo, instituir o índice porosidade/teor volumétrico de cimento (η/Civ) como um parâmetro de estado para areias artificialmente cimentadas, por ser um critério racional que relaciona a porosidade da mistura compactada com o teor volumétrico de cimento adicionado. A partir da utilização desse parâmetro, é possível calibrar a quantidade de cimento e a energia de compactação utilizada, a fim de proporcionar uma mistura que atenda aos requisitos de projeto e que seja viável de executar em obra com os recursos materiais e financeiros disponíveis. O programa experimental compreendeu a realização de 17 ensaios triaxiais, drenados e não drenados, analisados em conjunto com resultados já obtidos em estudos anteriores. Análises do comportamento tensão-deformação, variação volumétrica-deformação axial, geração de poropressão, trajetórias de tensões drenadas e não drenadas, envoltórias de resistência, comportamento tensão-dilatância, da aplicação da teoria do estado crítico e uma breve análise estatística embasaram a comprovação de que o parâmetro η/Civ é adequado para previsão do comportamento de corpos de prova de areia artificialmente cimentados. / The adoption of soil improvement techniques is becoming more frequent in geotechnical works, however, the dosage criteria and the parameters used to predict the soil behavior do not seem to follow the technological evolution of these techniques. The state parameter for sands (ψ) cannot represent the behavior of artificially cemented sands because it considers only the influence of the void ratio and the stress state. It is proposed to establish the porosity/volumetric content of cement (η/Civ) as a state parameter for artificially cemented sands, since it is a rational criterion which relates the porosity of the compacted mixture to the volumetric content of cement added. By using this parameter, it is possible to calibrate the amount of cement and the compaction energy used in order to provide a mixture that meets the design requirements and that is feasible to perform on site construction with the material and financial resources available there. The experimental program included the realization of 17 triaxial testes, performed in the drained and undrained conditions, analyzed simultaneously with other results obtained from previous studies. Analysis of stress-strain behavior, volumetric variation-axial strain, pore pressure development, drained and non-drained stress paths, resistance envelope, stress-dilatation behavior, the application of the critical state theory, and a brief statistical analysis supported that the η/Civ parameter is suitable for predicting the behavior of artificially cemented sand specimens.

A adoção de técnicas de melhoramento de solos é prática cada vez mais recorrente em obras geotécnicas, contudo, os critérios de dosagem e parâmetros de previsão do comportamento desses solos parecem não acompanhar a evolução tecnológica das referidas técnicas. O parâmetro de estado para areias (ψ) não consegue representar o comportamento de areias artificialmente cimentadas, por levar em consideração apenas a influência do índice de vazios e do estado de tensões. Propõe-se, neste estudo, instituir o índice porosidade/teor volumétrico de cimento (η/Civ) como um parâmetro de estado para areias artificialmente cimentadas, por ser um critério racional que relaciona a porosidade da mistura compactada com o teor volumétrico de cimento adicionado. A partir da utilização desse parâmetro, é possível calibrar a quantidade de cimento e a energia de compactação utilizada, a fim de proporcionar uma mistura que atenda aos requisitos de projeto e que seja viável de executar em obra com os recursos materiais e financeiros disponíveis. O programa experimental compreendeu a realização de 17 ensaios triaxiais, drenados e não drenados, analisados em conjunto com resultados já obtidos em estudos anteriores. Análises do comportamento tensão-deformação, variação volumétrica-deformação axial, geração de poropressão, trajetórias de tensões drenadas e não drenadas, envoltórias de resistência, comportamento tensão-dilatância, da aplicação da teoria do estado crítico e uma breve análise estatística embasaram a comprovação de que o parâmetro η/Civ é adequado para previsão do comportamento de corpos de prova de areia artificialmente cimentados. / The adoption of soil improvement techniques is becoming more frequent in geotechnical works, however, the dosage criteria and the parameters used to predict the soil behavior do not seem to follow the technological evolution of these techniques. The state parameter for sands (ψ) cannot represent the behavior of artificially cemented sands because it considers only the influence of the void ratio and the stress state. It is proposed to establish the porosity/volumetric content of cement (η/Civ) as a state parameter for artificially cemented sands, since it is a rational criterion which relates the porosity of the compacted mixture to the volumetric content of cement added. By using this parameter, it is possible to calibrate the amount of cement and the compaction energy used in order to provide a mixture that meets the design requirements and that is feasible to perform on site construction with the material and financial resources available there. The experimental program included the realization of 17 triaxial testes, performed in the drained and undrained conditions, analyzed simultaneously with other results obtained from previous studies. Analysis of stress-strain behavior, volumetric variation-axial strain, pore pressure development, drained and non-drained stress paths, resistance envelope, stress-dilatation behavior, the application of the critical state theory, and a brief statistical analysis supported that the η/Civ parameter is suitable for predicting the behavior of artificially cemented sand specimens.

The construction industry is closely tied to economic development economies, and increasing demand also presents a significant contribution to environmental degradation. The construction industry’s impact to climate change is led by the 8% contribution from the production of concrete mixtures, more specifically, the production of cement. The combination of using advanced mixdesign techniques (e.g., particle packing models -PPM) and more sustainable ingredients poses as a promising alternative to overcome concrete environmental impact. However, there is a lack of studies regarding the fresh state difficulties arising from the aforementioned combination. Therefore, this work appraises the use of mobility parameters to overcome the fresh state issue raised when mix-designing mortar mixtures through PPM and with high volume of limestone filler. Twelve mixtures were developed with distinct cement content ranging from 150 kg/m3 to 320 kg/m3. To produce sustainable mortar, besides using PPM, cement content was replaced by limestone filler. Time dependent fresh state analysis was performed using mortar slump flow and a rheological profile. In the hardened states, the compressive strength, porosity, surface electrical resistivity tests were performed. The main findings of the project observed a strong correlation between mobility parameters and five distinct rheological parameters: flow behaviour parameter, high shear rate viscosity and shear stress, low shear rate viscosity and shear stress. Additionally, in the hardened state, a dilution parameter IPScement was used to appraise the dilution and filler effect of the mortar mixtures. The works highlighted a promising method to produce eco-efficient mortars.

O objetivo deste trabalho é apresentar uma metodologia que possibilita a obtenção de uma linha de concretos auto-adensáveis de alta resistência, econômicos e com reduzido impacto ambiental quando comparados com os concretos correntes. Para atingir estes resultados foram estabelecidos critérios de dosagem e de produção visando à sinergia entre os materiais constituintes do concreto. Foram pesquisados métodos de empacotamento dos agregados e adições minerais, estudada a interação entre o aditivo superplastificante e os materiais cimentícios e a incorporação de fibras de lã-de-rocha ou poliamida. Os concretos com matriz densa sob efeito de temperaturas elevadas tendem a sofrer lascamentos explosivos. Diante disso foi verificado o comportamento de corpos de prova e os resultados indicaram a importância da adição da fibra de poliamida nessa condição, onde o concreto resistiu a uma temperatura de 400ºC. Ensaios de resistência à abrasão indicaram que a fibra de lã-de-rocha melhora essa propriedade do concreto e, como esperado, essa adição não inibe o lascamento explosivo do concreto. Também foram determinadas as propriedades mecânicas dos concretos e concluiu-se que é possível o emprego de um concreto estrutural auto-adensável com consumo de cimento Portland da ordem de 325 kg/\'M POT.3\', fc7 = 53 MPa, fc28 = 71 MPa e Ec28 = 43 GPa. Devido à ação das adições minerais, estes concretos atingiram uma grande reserva de resistência à compressão após a idade de referência de 28 dias, obtendo-se 89 MPa aos 131 dias de idade. A densificação da pasta hidratada, a melhoria da zona de interface desta com os agregados, além da fissuração reduzida decorrente do baixo consumo de cimento e da adição de fibras indicam que este material tem desempenho superior ao prescrito pela NBR 6118 para as diversas classes de agressividade ambiental e de resistência. / The aim of this work is to show a methodology that allows to realize a set of high strength self-consolidating concrete, economic and with lower environmental impact when compared with current concretes. To get these results, criteria for production and mix design had been established aiming at to synergy between constituent materials of the concrete. Methods of particles packing (aggregates and mineral additions), the interaction between the superplasticizer and cementitious materials and the fiber incorporation were researched. The concretes with dense matrix under effect of high temperatures are susceptible to explosive spalling. In this situation, concretes were evaluated by testing cylindrical specimens and results evidenced the importance of the polyamide fiber when the concrete supported 400ºC. Tests of abrasion resistance indicated a good application for the wool-of-rock fiber, but this material not avoids explosive spalling. The mechanical properties of the concretes were determined and show that is possible to product a self consolidate concrete with low cement content (325 kg/\'M POT.3\'), fc7 = 53 MPa, fc28 = 71 MPa and Ec28 = 43 GPa. Due to action of the mineral additions, these concretes had a great reserve of compressive strength after the age of reference of 28 days and achieved 89 MPa at 131 days of age. The high density cement paste, the improvement of the matrix-aggregate interfacial zone and the reduced cracking due to the low cement content and the fibre addition indicate that these materials has superior performance to those prescribed for the NBR 6118 for diverse strength classes and aggressive environmental exposure.