The Deep Mixing Method (DMM) is a widely used, in-situ ground improvement technique that modifies and improves the engineering properties of soil by blending the soil with a cementitious binder. Laboratory specimens were prepared to represent soil improved by the wet method of deep mixing, in which the binder is delivered in the form of a cement-water slurry. To study the influence of curing temperature on the strength of the treated soil, specimens were cured in temperature-controlled water baths for the desired curing time. After curing, unconfined compressive strength (UCS) tests were conducted on the specimens. To investigate the optimum mix design for the wet method of deep mixing, UCS tests were performed to measure the strength of cured specimens, and laboratory miniature vane shear tests were conducted on uncured specimens to measure the undrained shear strength (su), which is used to represent the consistency of the mixture right after mixing. The consistency is important for field mixing because a softer mixture is easier to mix thoroughly. Based on the UCS test results, an equation that can provide a good fit to the strength data of the cured binder-treated soil is proposed. When the curing temperature was changed during curing, the UCS of the specimen cured at a low temperature and then cured at a high temperature was greater than the UCS of the specimen cured at a high temperature first. This seems to be due to different effects of elevated curing temperatures at early and late curing times on the cement reaction rates, such that elevating the curing temperature later produces a more constant reaction rate, which contributes to the reaction efficiency. An optimum mix design that minimizes the amount of binder while satisfying both a target strength of the cured mixture and a target consistency of the uncured mixture can be established by using the fitted equations for UCS and su. The amount of binder required for the optimum mix design increases as the plasticity of the base soil increases and the water content of the base soil (wbase soil) decreases. / Master of Science / The Deep Mixing Method (DMM) is a ground improvement technique widely used to improve the strength and stiffness of loose sands, soft clays, and organic soils. The DMM is useful for both inland and coastal construction. There are two types of deep mixing. The dry method of deep mixing involves adding the binder in the form of dry powder, and the wet method of deep mixing involves mixing binder-water slurry with the soil. The strength of the cured mixture is significantly influenced by the amount of added cement and water, the curing time, and the curing temperature. This research evaluates the influence of curing temperature on the strength of cured cement-treated soil mixture. Mixture proportions and curing conditions also influence the consistency of the mixture right after mixing, which is important because it affects the amount of mixing energy necessary to thoroughly mix the binder slurry with the soil. This research developed and evaluated fitting equations that correlate the cured mixture strength and the uncured mixture consistency with mixture proportions and curing conditions. These fitting equations can then be used to select an economical and practical mix design method that minimizes the amount of binder needed to achieve both the desired cured strength and uncured consistency. The amount of binder required for the optimum mix design increases as the plasticity of the base soil increases and the water content of the base soil (wbase soil) decreases.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25251号 / 工博第5210号 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 安原 英明, 准教授 橋本 涼太, 准教授 澤村 康生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, Portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, 1.) incorporation of waste materials in portland cement synthesis, and 2.) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S–C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate-belite cement that contained medium C4A3 S and C2S contents showed good dimensional stability, sulfate resistance, and compressive strength development and was considered the optimum phase composition for calcium sulfoaluminate-belite cement in terms of comparable performance characteristics to portland cement. Furthermore, two calcium sulfoaluminate-belite cement clinkers were successfully synthesized from natural and waste materials such as limestone, bauxite, flue gas desulfurization sludge, Class C fly ash, and fluidized bed ash proportioned to the optimum calcium sulfoaluminate-belite cement synthesized from reagent-grade chemicals. Waste materials composed 30% and 41% of the raw ingredients. The two calcium sulfoaluminate-belite cements synthesized from natural and waste materials showed good dimensional stability, sulfate resistance, and compressive strength development, comparable to commercial portland cement. / text

The current generation of Glass Ionomer Cements (GICs) have many advantageous properties over other dental restorative materials but lack the compressive strength of these other materials. The aim of this project is to increase the compressive strength of conventional Glass Poly-Vinyl-Phosphonate cement by inclusion of reactive sub-micron filler particles. The setting characteristics, chemical reactivity and cement strength have been found using oscillating rheology, infrared spectrometry, nuclear magnetic spectrometry, transmission electron microscopy, potentiometer analysis, laser diffractometry and mechanical analysis. The addition of sub-micron filler particles in direct weight by weight replacement of aluminosilicate glass of a control material has increased the ultimate compressive strength of the new cement from 206MPa (control) to 250MPa after 365 days of aging. The strength of the new filler enhanced cements were comparable with the control material after 3 hours. The setting chemistry of the filler enhanced cements follows the same order as the control cement but at a decelerated rate. Theoretical modelling found that a large volume of sub-micron filler could fit into interstitial spacing in formed cement however the alteration of the aluminosilicate glass to polyelectrolyte ratio has been found to drastically alter the cement setting time. The use of cubic and polyhedral shaped filler particles as supposed to spherical particles may increase the cement strength further as greater packing densities are achieved. The formulation of a Glass Ionomer Cement with increased compressive strength may find use as a posterior restorative or as a better material for restoration of lesions and cavity liners.

This master thesis presents the effects of fly ash on the properties of alkali activated slag concrete, commonly referred as Geopolymer concrete (GPC). Cement manufacturer are major producers of CO2 which negatively affects the environment. Due to the increased construction activities and environmental concern, it is necessary to introduce alternative and eco-friendly binders for concrete. Slag and fly ash based concrete, which is by-product from industrial waste, is probably the best replacement for OPC concrete due to less or nil environmental issue. Most of the researchers have already concluded that slag and fly ash can be used as binders in concrete by activating them with alkali activator solution (e.g. by sodium silicate or sodium carbonate). In the present work concretes were produced by varying the proportion of slag to fly ash (40:60, 50:50, 60:40 & 80:20); amount of alkali activators (5, 10 & 14) and chemical modulus of sodium silicate (Ms) (0.25, 0.5 & 1).  Setting times and compressive strength values were evaluated. Results showed that decrease in fly ash content irrespective of % of alkali activators and alkali modulus (Ms), the compressive strength was increasing and setting time was getting shorter. The produced concretes showed increasing compressive strength with increase in % of alkali activator for Ms 0.5 and 1, while for Ms=0.25 the strength was decreasing with increase in % of alkali activators. From this it can be concluded that, Ms=0.5 was the optimum point below which the reaction got slower. Based on the initial investigations, mix S8:F2-SS10(1) and S8:F2-SS10(0.5) showed most promising results in terms of fresh and hardened concrete properties and were easy to handle. Consequently, the above mentioned mixture was chosen to be studied in more detail. The experimental program for these mixes included determination of slump flow, compressive strength (7, 14, 28 days) and shrinkage (drying and autogenous). The results shows that, strength increased with time and comparatively mix with Ms=0.5 showed higher compressive strength than mix with Ms=1, due to higher alkalinity of the pore solution. Mix with Ms=1 showed higher drying shrinkage compared to mix with Ms=0.5, which was explained by higher alkalinity of the solutions (Ms=0.5) leading to rapid formation of aluminosilicate gel. Autogenous shrinkage appeared to be higher for mix with Ms=0.5. This was associated with lower modulus which leads to densification of concrete microstructure at early ages. Pore diameter decrease and the water trapped in the pores exerted increasing tensile stress resulting for higher autogenous shrinkage.

Preplaced aggregate concrete (PAC) is produced by grouting high workability cement based grouts among the voids of compacted coarse aggregate mass. Because of its low shrinkage, PAC has been used for many repair jobs like; tunnel lines, dams and bridge piers. Moreover, it has been used for underwater construction. Grout has a major effect on the properties of produced PAC and well defined grout controls the properties of resulted PAC. The effect of types and amount of powder materials, admixtures, sand and water content on the properties of fresh and hardened grout for the production of PAC have been investigated. Tests on hardened grout and PAC properties have also been carried out to investigate the most important effects. A correlation between hardened properties of grout and PAC has also been analyzed. Grout rheology using four different gradation sands at two different cement-sand and at different w/c ratios ratios has been identified experimentally; no added chemical admixtures or mineral additives had first employed, then superplasticizer (SP) was added at 2% and 1%, and finally a combination of 1% SP and pulverized fuel ash (Pfa) at 20% of the cement weight was employed for all mixes. Grout tests have included two point workability tests by the Viskomat NT, flow time funnel test, Colcrete flow meter test, and water bleeding test. After that, eighteen grout mixes with high workability were produced using three different sands at three w/c ratios and two c/s ratios with 1% SP and Pfa at 20% of the cement weight were designed. Eighteen hardened grout and PAC then produced and their compressive strength and sorptivity were tested. Grout rheology can be defined by the rheology of cement paste employed and the internal distance between sand particles. The effect of sand surface texture on grout rheology is important at very low internal distances. Fresh grout yield stress is the most important property which gives the same degree of sensitivity for all grouts regardless the material type and content used in the mix. There are strong relations between compressive strength of grout and PAC, but less correlation between them in sorptivity test because of the effect high quantity of coarse aggregate of PAC. Sorptivity of PAC is low comparing with different kinds of concrete suggesting its advantage for underwater construction.

Betong är idag och har länge varit det allra vanligaste byggnadsmaterial i Sverige. Det är ett robust och mångsidigt byggnadsmaterial med flera fördelar. Detta arbete är en experimentell studie av betongavfall från Hedareds sand & betong för betongprogrammet RE: Concrete och Högskolan i Borås. Betongavfallet krossas till ny ballast och därefter siktas och gjuts till ny betong enligt olika betongrecept. Försöken sker i betonglabbet i Högskolan i Borås för att krossa och tillverka betong. Grundreceptet har tillhandhållits av Hedareds sand & betong. Syftet med arbetet har varit att undersöka möjligheterna för att kunna använda återvunnen betong i nya bärande konstruktioner. Målet var att bevisa att det var tekniskt möjligt att åstadkomma en 100 % ersättning av ballast med återvunnen betong och få fram ny betong som passar den bärande stommen i en byggnad. Olika egenskaper undersöktes så som tryckhållfasthet för den nya betongen och partikelfördelning samt vattenabsorption för ballasten med målet att uppnå likvärdigt resultat som för referensbetongen. Resultatet visar att det är möjligt att kunna återvinna betong till 100 %. Arbetbarheten är bra i flertal försök men bör förbättras för att uppnå likvärdig arbetbarhet som referensbetongens. Referensbetongens tryckhållfasthet är 59 MPa och bästa tryckhållfasthet som erhållits för återvunnen betong är 57,2 MPa. Detta tyder på ett positivt resultat och den återvunna betongen i denna studie kan ersätta naturgrusballast i en bärande konstruktion till 100 %. / Concrete is and has been for a long time the most common building material in Sweden. It is a robust and multipurpose building material with several advantages. This report is about an experimental study of concrete waste from Hedareds sand & betong. The concrete waste is crushed to a new aggregate and then sifted and casted into new concrete. The study was conducted in the Concrete Laboratory at University of Borås for crushing and casting of concrete. Recipes are supplied by Hedareds sand & betong as a starting point, which is later modified gradually to achieve better results. The purpose of this study is to investigate the possibilities for using recycled concrete in new constructions. It is also examined if the recycled concrete is technically sustainable and if the workability is good enough for using in load bearing structures. Different properties are studied such as compressive strength, particle distribution, water absorption and workability to achieve equivalent results as the reference concrete. The result obtained in this study shows that it is possible to recycle concrete by replacing aggregates to 100 % in new concrete. Workability is good in several tests, but it should be improved to achieve the same workability as the reference concrete. The reference concrete's compressive strength is 59 MPa and the best compressive strength obtained for recycled concrete is 57.2 MPa. This indicates positive results and the recycled concrete in this study can replace ordinary concrete in a load bearing construction.

Betongindustrin ska enligt standard, varje vecka gjuta minst en kub per betongfamilj för att avstämma att hållfastheten som tillverkas inte understiger hållfastheten som kunden efterfrågat. Hållfastheten får inte vara lägre än den efterfrågade, men ingen standard påpekar hur mycket den kan överstiga. Dock kan en högre hållfasthet påverka konstruktionen negativt. En liten blandningsmassa tas ut från blandaren innan den skickas iväg till arbetsplatsen för att härdas i 28 dygn innan den trycks. Massan hälls i en kub och härdas i olika steg som ska utföras enligt standard. Det finns två olika härdningsprocesser, en enligt den svensk standarden och en enligt den europiska standarden. Det europeiska alternativet säger att betongkuben efter dag ett av härdning ska placeras i vattenbad med temperaturen 20±2 ºC fram till tryckningen. Den svenska standarden däremot säger att kuben efter första dagen av torkning ska härdas i vattenbad i 4 dygn och därefter placeras i ett härdningsutrymme med en relativ luftfuktighet mellan 40–80% med en temperatur på 20±2 ºC. Den luftlagrade ger en högre hållfasthet och ska därför räknas om med en omräkningsfaktor för att efterlikna den europiska standarden. Enligt de olika betongindustrierna kan dessa två härdningsprocesser ge samma hållfasthet vissa gånger, men andra gånger inte. Detta arbetet har därför gått ut på att jämföra de två processerna för att kunna komma fram till varför det kan variera och vad dessa faktorer beror på. För att kunna komma fram till ett resultat har arbetet valt att fördjupa sig i hållfastheten för betong genom litteraturstudier och även gjuta kuber som senare skulle tryckas för att se över hur hållfastheten varierar för de olika kuberna.   Det studien har kommit fram till är att kuber inte alltid kommer ge samma hållfasthet fastän de utgår från samma blandning och härdning. Detta på grund av att betong består av olika beståndsdelar såsom ballast med olika storlekar som är svårt att fördela lika mycket i varje kub. Utrustningen och genomförandet under kubgjutning kan även vara en faktor som kan påverka hållfastheten där en kub kan ha vibrerats eller blandats lite mer än de andra. En annan faktor som kan ha gjort skillnad mellan härdningsprocesserna är omräkningsfaktorn för kuber som har härdat i luftutrymmet. Den relativa fuktigheten i lokalen låg nära 40% för kuberna och omräkningsfaktor enligt standard ska vara den samma för den relativa luftfuktigheten mellan 40–80%, detta antas vara något som bör varas tydligare med då det i betonghandboken stod att omräkningsfaktor kan ändras beroende på hur många procent den ligger på. Detta är en av anledningar till att den europiska standarden anses vara den mer effektiva processen. En annan anledning är även att kuber i vatten hela tiden får tillräckligt med luft runt om, till skillnad från härdningsutrymmet där fuktigheten varierar konstant. / According to the standard, the concrete industry must, every week, cast at least one cube per concrete family to reconcile that the strength produced is not less than the strength demanded by the customer. To calculate the compressive strength of the concrete, two different curing processes can be used, both processes occur over 28 days and then can test the compressive strength. The processes are the Swedish standard and the European standard where the difference is the curing process and that’s the Swedish standard provides a higher strength and needs to be applied according to the European currency by means of a conversion factor. This work has therefore been to compare the two processes in order to be able to determine why it can vary and what these factors depend on.   This study has come up with that the cubes will not always give the same strength even though they are based on the same formula and curing. This is because concrete consists of different components such as aggregates with different sizes that are difficult to allocate as much in each cube. This is one of the reasons why the European standard is considered to be the more effective process.

A criação de programas federais voltados para o desenvolvimento da infraestrutura brasileira no final da década passada resultou no aquecimento do setor de construção civil. Nesse contexto, o sistema de paredes de concreto moldadas no local se destacou devido à sua alta produtividade e repetitividade. Os requisitos e procedimentos para o dimensionamento de paredes de concreto moldadas no local são contemplados na NBR 16055:2012. Dentre as abordagens consideradas nessa norma, ressalta-se a recomendação do uso de concreto autoadensável. No entanto, alguns pontos de interesse não são contemplados na regulamentação vigente como, por exemplo, a incorporação de ar na composição do concreto, bem como os limites de teores de ar incorporado. Assim, a presente pesquisa busca avaliar a influência da incorporação de ar no comportamento de concretos autoadensáveis destinados à execução de paredes de concreto moldadas no local. Para isso, foram produzidos dois traços de concreto autoadensável de classes de resistência C25 e C40 e, a partir de cada um deles, produzidos outros dois traços modificados com aditivo incorporador de ar, variando o teor de ar incorporado, em um total de seis misturas cujas propriedades foram avaliadas tanto no estado fresco quanto no estado endurecido. Além disso, foram moldadas paredes de concreto a fim de analisar a estrutura interna do material com aparelho de ultrassom e o acabamento superficial do elemento por meio de análise de imagens. No caso da classe C25, os resultados demonstram que a influência do teor de ar para os traços modificados foi tão significativa que os concretos produzidos se tornaram inadequados para uso estrutural. Por outro lado, apesar da elevada perda de resistência à compressão aos 28 dias, os dois traços produzidos com incorporação de ar no concreto de classe C40 se adequam às recomendações da NBR 16055:2012. Alia-se a isso o fato de que, quando da execução das paredes em laboratório, os concretos utilizados demonstraram grande capacidade de preenchimento, resultando em elementos com bom acabamento superficial e estrutura interna homogênea, mesmo em regiões de difícil acesso. Sendo assim, o presente trabalho propõe traços muito promissores para utilização em paredes de concreto moldadas no local. / The creation of federal programs aimed at the development of Brazilian infrastructure at the end of the last decade resulted in the heating of civil construction sector. In this context, the system of concrete walls cast in place stood out due to its high productivity and repetitiveness. The requirements and procedures for the design of concrete walls cast in place are contemplated in the NBR 16055:2012. Among the several approaches considered in this code, the recommendation for the use of self-compacting concrete is emphasized. However, some points of interest are not considered in the current regulations, such as the incorporation of air in the concrete composition, as well as the limits for entrained air contents. Thus, the present research seeks to evaluate the influence of air entrainment in the behaviour of self-compacting concrete for the construction of concrete walls cast in place. For this, two self-compacting concrete mixes design of strength classes C25 and C40 were produced and, from each of them, two other mixes modified with air entraining admixture were produced, varying the entrained air content, in a total of six mixtures whose properties were evaluated in both fresh and hardened state. In addition, concrete walls were cast to analyse the internal structure with ultrasonic equipment and the element surface finish by image analysis. In the case of class C25, the results demonstrate that the influence of the air content for the modified mixes was so great that the concretes produced became inappropriate for structural use. On the other hand, despite the high loss of compressive strength at 28 days, the two mixes produced with entrained air in the concrete of class C40 respect the recommendations of the NBR 16055:2012. In addition, when the walls were cast in laboratory, the concretes used showed great filling capacity, resulting in structures with good surface finish and homogeneous internal structure, even in difficult access regions. Therefore, the present work proposes very promising mixes for use in concrete walls cast in place.

O objetivo deste trabalho é avaliar a influência da variação do teor de umidade no valor do módulo de resiliência (MR) de um solo argiloso de subleito, tendo em vista que este parâmetro é muito susceptível à variações climáticas ambientais. Foram realizados ensaios triaxiais cíclicos para se estimar o módulo de resiliência de corpos de prova ensaiados em diversas condições de umidade. Verificou-se que o MR é influenciado pela tensão desvio, de forma que aquele aumenta com o acréscimo desta. Constatou-se que os corpos de prova moldados na Wot e submetidos a trajetórias de secagem e umedecimento alcançaram valores de MR superiores e inferiores, respectivamente, ao se comparar com o MR de corpos de prova ensaiados na Wot. Este fato foi também observado para os corpos de prova moldados com massa específica seca máxima, em teores de umidade abaixo e acima do teor ótimo. Determinou-se, ainda, a sucção no solo através do método do papel filtro e levantou-se a sua curva característica. Verificou-se que à medida que a umidade aumenta, a sucção diminui. Observou-se que o valor do MR aumenta com o aumento da sucção no solo. Este crescimento é tanto maior quanto maior seja a tensão desvio aplicada. Foi possível determinar a relação entre o MR, a tensão desvio e o módulo tangente inicial (Eo), proveniente dos ensaios de compressão simples. Relacionou-se, também, o Eo e a sucção no solo. / The aim of this work is to evaluate the influence of moisture content variation in resilient modulus value (MR) of a subgrade clayey soil, considering that this parameter is very susceptible to environmental climatic variations. Cyclic triaxial tests were performed to acess resilient modulus of specimens tested in several moisture conditions. lt has been verified that MR is influenced by deviator stress, so that the former increases with the latter increases. lt has been confirmed that specimens molded in Wot and submited to a drying and moistening route reached MR values higher and lower, respectively, to compare with MR of specimens tested in Wot. This fact was also observed for the specimens molded with dry density, in moisture contents below and above of optimum moisture content. lt has been also determined the soil suction using filter paper method and it has been built its characteristic curve. lt has been verified that when moisture increases, the suction decreases. lt has been observed that MR value increases with the soil suction increase. This increase is as bigger as bigger the applied deviator stress be. lt was possible to determine the relationship between MR, deviator stress and parameters from compressive strength tests. lt has been related parameters from compressive strength tests and soil suction.