Dissertations / Theses on the topic 'Clay compaction'

Several engineering structures for geotechnical engineering applications are constructed using compacted fine-grained soils (i.e., dams, road embankments, pavements, canals, and waste containment structures such as soil covers and liners). The compacted fine-grained soils are typically in a state of unsaturated condition and plastic in nature. There is a growing interest in recent years to apply the mechanics of unsaturated soils in the design of geotechnical structures constructed with compacted fine-grained soils. The soil-water retention curve (SWRC) is being used as a key tool in extending the mechanics of unsaturated soils into engineering practice. Conventionally, SWRC is determined in the laboratory without taking account the volume changes with respect to soil suction. The water retention characteristics of plastic soils depend on the pore-size distribution, compressibility characteristics and the volume change behavior. For this reason, the conventional procedures that are used in the measurement of the SWRC may not provide reliable information. Therefore, the engineering behavior of compacted fine-grained soils cannot be reliably estimated or predicted if the volume change behavior with respect to suction is not considered while measuring the water retention curves for compacted fine-grained soils. In this thesis, a comprehensive experimental program is undertaken to determine the water retention characteristics of a local plastic soil, Champlain sea clay. This soil is commonly used in the construction of several structures in Ottawa and Quebec region. The SWRCs of Champlain sea clay were measured on specimens that were statically or dynamically compacted at different water contents and densities using different compaction energies. The suction measurements of the individually compacted specimens were determined using axis-translation technique and thermocouple psychrometers. The volume changes of the specimens were measured at each value of suction while determining the SWRC. In light of the experimental results, the parameters that influence the SWRC behavior such as compaction type (i.e., static or dynamic) and effort, initial compaction water content and void ratio on the water retention behavior of compacted fine-grained soils were investigated. In addition, a database of 16 compacted plastic soils with measured SWRCs and their conventional properties from the published literature was summarized. Relationships between the parameters of the SWRC, namely, the rate of desorption and the conventional soil properties were studied using the results of the present experimental program and the information from the database. This study shows that liquid limit coupled with clay fraction can be a useful tool to correlate with the rate of desorption for compacted soils. Based on this information, a new technique is proposed for the estimation of the entire SWRC of compacted fine-grained soils following the drying path. The required information for using this technique includes one point measurement of suction versus water content in the suction range of 0-500 kPa, along with data on the liquid limit and the clay fraction. The proposed technique provides good comparison between the measured and estimated SWRCs for the data studied in this research program. This technique can be used in the preliminary design stages of a project when detailed information about the soil is no available. In addition a state-of-art literature review on the devices presently available for the measurement of soil suction is summarized.

Persistent soil compaction by heavy-axle-load vehicles is a growing concern for the long-term productivity of clay soils. For optimum soil management, however, we must be able to evaluate adequately soil structural damages. This study compares different methods of assessing soil structure as affected by compaction and subsoiling treatments in a clay soil under corn production.
The tests used were: total porosity as calculated from densimeter readings and from soil cores; structural porosity; water desorption characteristics; and soil profile examination. These tests were performed in three layers of 20 cm and evaluation was based on their practicality and their ability to differentiate between treatments and to correlate with corn yield.
The results confirm that total porosity is a poor indicator of compaction in the subsoil. In soil profile assessments, ped descriptions were preferable to examination of pores. Water content and saturation deficit at $-$4.0 and $-$100 kPa were the best indicators of treatments and plant response.

Clay mineral diagenesis has a considerable effect on the physical properties of siliciclastic mudstones, with important implications for pore pressure prediction. The dominant clay mineral reaction, the conversion of smectite to illite, involves a series of dissolution and reprecipitation reactions which results in a significant change in the orientation of the clay mineral fabric. Unloading is a direct result of clay mineral diagenesis and concomitant fabric destabilisation, due to the local transfer of load from dissolving detrital clay grains to fluid. Pore pressure is then a function of the rate at which it is generated by clay mineral diagenesis (and other mechanisms such as disequilibrium compaction) and the rate at which it is dissipated by compaction and fluid flow. Clear evidence has been found for chemical compaction (porosity loss/sediment volume reduction) associated with illitization of smectite in Miocene mudstones in the Central Malay Basin, in Cretaceous mudstones at Haltenbanken, offshore mid-Norway, in Cretaceous to Tertiary mudstones in the Sergipe-Alagoas Basin, offshore Brazil and in Triassic mudstones in the North Sea Central Graben from measured physical, textural, and mineralogical properties, and from log responses. In addition to this diagenetically mature, illitized mudstones continue to compact mechanically with increasing effective stress. The newly presented data have been interpreted to discriminate between two models for the chemical compaction of diagenetically altered mudstones proposed by previous researchers: (effective) stress-independent chemical compaction and chemically-enhanced mechanical compaction. Key evidence in favour of the chemically-enhanced mechanical compaction model comes from density logs of Cretaceous mudstones at the Halten Terrace, offshore mid-Norway in association with the pore pressure history inferred by previous pore pressure analysis. This model is also consistent with the petrographic evidence that clay-rich siliciclastic mudstones have a clay-supported matrix both before and after illitization. Established methods of pore pressure estimation do not correctly account for the mechanical and chemical contributions to mudstone compaction, except empirically or in favourable circumstances where use can be made of data from offset wells with similar lithology, burial history and temperature history.

In this study, the relationship between soil suction and shear strength parameters of compacted METU campus clay were investigated at different moisture contents. Soil samples were tested at optimum moisture content (i.e. w=20.8%), at dry side of optimum moisture content (i.e. w=14.8%, 16.8%, 18.8%) and at wet side of optimum moisture content (i.e. w=22.8%, 24.8%, 26.8%). Direct shear tests were performed to measure shear strength parameters (c'
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) and soil suctions were measured by filter paper method after direct shear tests. These relationships were also investigated on soaked samples. The trends for suction, angle of internal friction and cohesion, which change on the dry side and wet side of optimum moisture content, were analyzed. The compacted METU campus clay gains granular soil fabric at the dry side of optimum moisture content. As moisture content increases, cohesion increases up to optimum moisture content and then decreases. But angle of internal friction decreases as moisture content increases. Soaking affects the samples more which are on the dry side of optimum moisture content. The soil suction (total suction and matric suction) affects the shear strength, and an increase in soil suction increases the shear strength.

Natural soils in work-sites are sometimes detrimental to the construction of engineering projects. Problematic soils such as soft and expansive soils are a real source of concern to the long-term stability of structures if care is not taken. Expansive soils could generate immense distress due to their volume change in response to a slight change in their water content. On the other hand, soft soils are characterised by their low shear strength and poor workability. In earthwork, replacing these soils is sometimes economically and sustainably unjustifiable in particular if they can be stabilised to improve their behaviour. Several techniques have evolved to enable construction on problematic soils such as reinforcement using fibre and planar layers and piled reinforced embankments. Chemical treatment using, e.g. lime and/or cement is an alternative method to seize the volume change of swelling clays. The use of lime as a binding agent is becoming a popular method due to its abundant availability and cost-effectiveness. When mixed with swelling clays, lime enhances the mechanical properties, workability and reduces sensitivity to absorption and release of water. There is a consensus in the literature about the primary mechanisms, namely cation exchange, flocculation and pozzolanic reaction, which cause the changes in the soil characteristics after adding lime in the presence of water. The dispute is about whether these mechanisms occur in a sequential or synchronous manner. More precisely, the controversy concerns the formation of cementitious compounds in the pozzolanic reaction, whether it starts directly or after the cation exchange and flocculation are completed. The current study aims to monitor the signs of the formation of such compounds using a geotechnical approach. In this context, the effect of delayed compaction, lime content, mineralogy composition, curing time and environmental temperature on the properties of lime-treated clays were investigated. The compaction, swelling and permeability, and unconfind compression strength tests were chosen to evaluate such effect. In general, the results of the geotechnical approach have been characterised by their scattering. The sources of this dispersion are numerous and include sampling methods, pulverisation degree, mixing times and delay of compaction process, a pre-test temperature and humidity, differences in dry unit weight values, and testing methods. Therefore, in the current study, several precautions have been set to reduce the scattering in the results of such tests so that they can be used efficiently to monitor the evolution in the properties that are directly related to the formation and development of cementitious compounds. Four clays with different mineralogy compositions, covering a wide range of liquid limits, were chosen. The mechanical and hydraulic behaviour of such clays that had been treated by various concentrations of lime up to 25% at two ambient temperatures of 20 and 40oC were monitored for various curing times. The results indicated that the timing of the onset of changes in mechanical and hydraulic properties that are related to the formation of cementitious compounds depends on the mineralogy composition of treated clay and ambient temperature. Moreover, at a given temperature, the continuity of such changes in the characteristics of a given lime-treated clay depends on the lime availability.

Dans le cadre de l'étude du vieillissement d'un sol fin au laboratoire, nous avons réalisé des essais classiques de cisaillement, à l’oedomètre et de perméabilité, sur des échantillons du limon de Xeuilley. L’effet du temps a été considéré à deux niveaux : d'une part, le temps de vieillissement après compactage à teneur en eau constante et le temps de vieillissement durant la consolidation. Les essais de cisaillement non consolidés non drainés ont été réalisés sur des échantillons préparés à des teneurs en eau différentes. Ils ont montré une augmentation de la résistance au cisaillement non drainée et du module de déformation liée à une diminution de la déformation à la rupture en fonction du temps. Ces mêmes effets ont été constatés pendant les essais de cisaillement consolidés non drainés dans des proportions différentes. Ceci est probablement dû aux mécanismes qui conditionnent le comportement drainé et non drainé du matériau durant le vieillissement. Les résultats des essais oedométriques ont aussi confirmé l'augmentation de la rigidité du matériau en fonction de l'âge des échantillons. Enfin, les essais de perméabilité ont montré que la perméabilité a tendance à diminuer en fonction du temps de stockage.

El presente trabajo de investigación tiene como fin determinar el porcentaje optimo del uso del material estabilizante, compuesto por la Ceniza de Bagazo de Caña de Azúcar (CBCA), y cal, con un enfoque económico y efectividad de uso en tanto a mejora del porcentaje de CBR de la subrasante clasificada como pobre o inadecuada. Dentro del marco de desarrollo del trabajo se encuentra el estudio de la influencia de la Ceniza de Bagazo de Caña de Azúcar (CBCA) en el suelo natural, del mismo modo que la cal; esto para entender los cambios en las propiedades físicas y mecánicas de la mezcla. El suelo en estudio es un suelo arcilloso de baja plasticidad según SUCS, y según AASHTO un A-6(8); este mezclado con 5%, 15% y 25% de Material Estabilizante respecto a la masa seca, con combinaciones, 100% CBCA, 75%CBCA y 25%Cal, 50%CBCA y 50%Cal, 100%Cal. Todas las Combinaciones especificadas se ensayaron para Proctor y CBR, y luego se analizaron cada uno de los resultados mediante un diagrama de Líneas para los dos ensayos. La proporción de material estabilizante es el 5% respecto a la masa seca de arcilla que presenta la mejora eficiente e inmediata el CBR, aumentando en un 110.81% respecto a la del suelo natural, y la densidad, aumentando en 54.7% respecto al suelo natural. Este porcentaje está compuesto por la combinación parcial de 50% de Cal y 50% de CBCA seleccionada con fines económicos, con la reducción de aplicación de cal.
The aim of this research work is to use agroindustry’s wastes in conjunction with traditional stabilizers, such as lime, to solve the problem of unpaved roads with poor or inadequate subgrade according to their CBR value. The fundamental objective of this research work was to study the influence of Sugar Cane Bagasse Ash (CBCA) in conjunction with Lime to enhancement the mechanical properties of low plasticity clay soils, according to AASHTO a A-6 (8) sub group’s soil. Likewise, some tests that were carried out in the research were the AASHTO standard compaction tests and CBR, to compare the natural soil sample and the global combinations 5%, 15% and 25% of Stabilizing Material applied to the natural soil, containing each of these the next four proportions (100% CBCA, 75% CBCA and 25% Cal, 50% CBCA and 50% Cal, 100% Cal). Among the most noteworthy results were soil improvements in compaction and CBR characteristics, reducing the incidence of Lime by 50%. The proportion of stabilizing material that presents the immediate and efficient enhancement is obtained with 5% Stabilizing Material, respect to the clay’s dry mass; with a partial combination of 50% of Lime and 50% of CBCA, increasing the CBR by 110.81% with respect to the natural soil’s CBR.
Tesis

Avec la compaction progressive des sédiments, la transformation des matières minérales et organiques est connue pour produire une eau moins salée que l'eau interstitielle d'origine, dont la composition aurait été similaire à celle de l'eau de mer. Le but de notre étude expérimentale était de simuler les processus diagénétique du flux de fluide, de la chaleur et de la compaction mécanique qui est impliqué dans le rafraîchissement de l'eau de formation à partir d'un échantillon d'argile saturé. Notre objectif était d'utiliser la chimie générale de l'eau, ainsi que les traceurs isotopiques Cloride et Bromide, pour suivre l'évolution de la production d'eau douce à travers le temps. La cellule de compression oedométrique à grande échelle qui a été développée pour les besoins de cette étude est nouvelle et rare en raison des pressions élevées de fluide, des contraintes mécaniques et des températures qui ont pu être appliquées aux échantillons d'argile durant les expériences, ainsi que de la collaboration multidisciplinaire entre des laboratoires réputés afin de contribuer à une compréhension fonctionnelle du comportement du Cl et du Br dans les processus géologiques. Il n'existe pas d'expérience multidisciplinaire similaire à grande échelle dans la littérature. Nous avons réalisé trois expériences de compactage qui ont durées jusqu'à environ 200 jours chacune, pendant lesquelles nous avons enregistré en continu la contrainte axiale (σ1), la pression du fluide interstitiel (Pi), la déformation axiale et les volumes de fluide dans les pompes d'injection et de collecte. Les expériences consistaient d'abord à saturer l'argile avec de l'eau de mer dans la grande cellule oedomérienne, puis à la compacter en 5 ou 10 étapes d'augmentation de la contrainte verticale jusqu'à 150 MPa et de l'augmentation de la température jusqu'à 150°C, tout en maintenant la pression du fluide interstitiel aussi proche que possible de 45 MPa. Le suivi continu de la déformation axiale et la surveillance de la composition de l'eau entrée et expulsée ont permis d'établir un bilan massique hydrique et chimique du système. Nous avons donc pu calculer quelle devrait être la composition de l'eau interstitielle restante, à chaque étape de compactage consécutive. De plus, le logiciel de modélisation SURP, développé par le BRGM, nous a permis de comprendre quelle proportion de cette eau expulsée était le résultat de la déshydratation des minéraux argileux. Une véritable transformation minérale n'a pas été observée. Ni par l'exercice de modélisation, ni par la caractérisation minérale. Nous avons constaté que la chimie et le comportement isotopique sont considérablement différents entre une argile gonflante (MX80 contenant 71% de smectite) et une argile non gonflante (marne de Sainte Suzanne contenant 61% d'illite). Dans notre étude, pour l'argile gonflante nous avons observé une diminution générale des concentrations en cations et anions dans l'eau expulsée, tandis que sa concentration augmentait légèrement dans le fluide interstitiel restant. Ce n'était pas le cas pour l'argile non gonflante. Ensuite, un rafraîchissement plus important de l'eau expulsée s'est produit pendant l'expérience de compactage à une température plus élevée. Nous avons également observé que comme Br est plus efficacement filtré par les argiles que le Cl en raison de son occurrence naturelle beaucoup plus faible, cela se traduit par une plus grande gamme de fractionnement isotopique pour Br (valeur δ81Br de l'eau expulsée de 0,9 ‰ jusqu'à 1,5‰) que pour Cl (valeur δ37Cl de l'eau expulsée de -0,1‰ jusqu'à -0,5‰), et ceci dans les trois expériences de compactage. Il est supposé que la rétention significative de Cl et Br dans l'eau interstitielle de la MX80 compactée indique une ultrafiltration δ37Cl et δ81Br sont des traceurs prometteurs pour mieux interpréter l'origine et l'évolution des eaux de formation dans les bassins sédimentaires
With progressive compaction of the sediments, mineral and organic matter transformation are known to produce water that is less saline than the original pore water, which would have been similar in composition to ocean water. This freshening has been linked to over pressure generation as a consequence of the material transformation. The aim of our experimental investigation/work was to simulate the diagenetic processes of fluid and heat flow, and mechanical compaction that are involved in the freshening of formation water from a saturated clay sample. Our objective was to use the general water chemistry, as well as Cloride and Bromide isotopic tracers, to track the evolution of freshwater production with time.The large-scale oedometric compression cell that was developed for the purpose of this study is novel and rare due to the high fluid pressures, mechanical stresses and temperatures that could be applied on the clay samples during the experiments, and the multi-disciplinary collaboration between well-reputed laboratories in order to contribute to a functional understanding of Cl and Br behaviour in geological processes. There are no similar multi-disciplinary large-scale experiments in the literature.We did three compaction experiments that lasted up to around 200 days each during which we continuously recorded axial stress, pore fluid pressure, axial deformation, and the volumes of fluids in injection and collector pumps. The experiments constituted first saturating the clay with ocean water in the large oedomertic cell, and then compacting it in either 5 or 10 steps of increasing vertical stress and temperature up to 150 MPa and 150°C, while maintaining the pore fluid pressure as close as possible to 45 MPa. Continuously following the axial deformation, and monitoring the composition of the input and expelled water allowed for a water and chemical mass balance of the system. We could therefore calculate what the remaining pore water composition should be, with each consecutive compaction step. Furthermore, the state of the art modelling software, SURP, developed by the BRGM, helped us to understand what proportion of that expelled water, was the result of clay mineral dehydration. True mineral transformation was not observed. Neither through the modelling exercise, nor through XRD mineral characterization.We found that the chemistry and isotope behavior is considerably different between swelling clay (MX80 containing 75 wt% smectite) and non-swelling clay (Sainte Suzanne marl containing 61 wt% illite & 7 wt% kaolinite). In our study we observed a general decrease of the cation and anion concentrations in the expelled water for swelling clay while its concentration slightly increased in the remaining pore fluid. This was not the case for non-swelling clay. Then, more freshening of the expelled water occurred during the compaction MX80 experiment at higher temperature.We also observed that as Br is much more effectively filtered by the clays than chlorine due to its much lower natural occurrence, this translates to a larger range of isotopic fractionation for Br (δ81Br value of the expelled water from 0.9 ‰ up to 1.5‰) than for Cl (δ37Cl value of the expelled water from -0.1‰ down to -0.5‰), in all three compaction experiments.It is supposed that significant retention of Cl and Br in the pore water of the compacted MX80 is indicative of ultrafiltration and that the surface chemistry of the clay in combination with decreasing porosity result in re-equilibration of compressed and overlapping diffuse double layers which in part, drive the anion and isotope evolution. δ37Cl and δ81Br are promising tracers to better interpret the origin and evolution of formation waters in sedimentary basins

O desenvolvimento econômico brasileiro depende da crescente produção agropecuária, aliada ao conservacionismo. O sistema de plantio direto é o manejo de solo que reúne o mais amplo conjunto de preceitos da agricultura conservacionista. As áreas agrícolas cultivadas sob plantio direto, entretanto, têm apresentado duas camadas de solo distintas: uma entre, aproximadamente, 0 e 7 cm de profundidade, com condições físicas e químicas favoráveis ao desenvolvimento radicular; e uma entre, aproximadamente, 7 e 20 cm de profundidade, com menor permeabilidade do solo ao ar e a água, elevada resistência à penetração e baixa fertilidade química do solo. Estas condições promovem a concentração do sistema radicular das plantas agrícolas cultivadas na camada mais superficial do solo (0 a 7 cm), motivando perdas de produtividade por estresse hídrico. A magnitude desse problema se estende a mais de 30 milhões de hectares de lavoura cultivada sob plantio direto no Brasil, colocando em risco as projeções de exuberância da agricultura no país. Assim, o desenvolvimento desta tese teve o objetivo de estudar fatores que, além do processo de compactação mecânica do solo, possam estar promovendo a estratificação física e química de solos altamente intemperizados cultivados sob sistema de plantio direto. Dentre os possíveis fatores causadores deste tipo de degradação, foram avaliados: i) a aplicação excessiva de calcário, exclusivamente em superfície, ocasionando, na camada de 0 a 7 cm, a elevação do pH do solo para além do ponto de carga zero do solo, elevando o potencial eletronegativo do solo e por consequência, promovendo a dispersão de argila; ii) a migração da argila dispersa no perfil do solo, pela água de percolação, como um fator promotor de degradação física em subsuperfície; iii) o aporte de fitomassa ao solo em quantidade e qualidade para manter a estabilidade estrutural dos solos cultivados. Os resultados obtidos mostraram que o movimento de calcário no perfil dos solos estudados é muito lento, limitando o efeito deste produto a poucos centímetros abaixo do local onde ele é depositado ou incorporado (2,5 cm em 130 semanas), independentemente da dose aplicada (até 33,2 Mg ha-1). Assim, a calagem superficial promove e intensifica a estratificação dos atributos químicos no perfil do solo, aumentando, demasiadamente, o pH próximo à superfície e sendo ineficiente em mitigar a acidez na subsuperficie destes solos. A concentração de calcário na camada mais superficial dos solos altamente intemperizados aumenta a eletronegatividade do solo, resultando na dispersão de argila. A migração dos argilominerais dispersos no perfil do solo, pela água de percolação, promove uma série de alterações estruturais, incluindo a diminuição da porosidade total e da continuidade dos poros e o aumento da densidade e da resistência do solo à penetração na camada subsuperficial. A diminuição da estabilidade estrutural dos Latossolos sob cultivo também está ligada ao aporte de material orgânico ao solo em quantidade e qualidade inferiores à que ocorre no solo sob sistema nativo. Os Latossolos cauliníticos são mais propensos a diminuição da estabilidade estrutural quando submetidos ao cultivo. Portanto, a recomendação de calagem em solos altamente intemperizados cultivados sob plantio direto, precisa considerar a mineralogia do solo e a possível degradação estrutural promovida pela calagem em excesso.
The economic development of Brazil depends upon the increasing agricultural production associated with conservation practices. The no-tillage system is the soil management practice that brings together the broadest set of principles for conservation agriculture. Areas under no-till system, however, generally have two completely different soils layers: a surface layer, around 0 to 7 cm, with physical and chemical conditions favorable for root development; and a sub-surface layer, around 7 to 20 cm, with lower permeability to air and water, high soil penetration resistance, and low soil fertility. The existence of these stratified layers dramatically restricts the development of the root system into the sub-surface soil layer, which may result in reducing plant productivity by water deficit. This problem exists on more than 30 million hectares cultivated under no-tillage system in Brazil, and can compromise the optimistic projections of agricultural growth in the country. Therefore, more research is necessary to explore challenges that come with no-tillage. The aim of this thesis was to study the factors that can promote the physical and chemical stratification of highly weathered soils cultivated under no-till system. Among the factors that could cause this degradation, the following were studied: i) the application of excessive lime only on surface soil, or into the uppermost soil layer, which can increase its pH to levels beyond of the zero point of charge of soil, raising its electronegative potential and promoting, as a consequence, the clay dispersion; ii) the dispersed clay migration thtough the soil profile, by the percolation water, as a factor of physical degradation of sub-surface of soil cultiveted under no-tillage; and iii) the aplication of phytomass to the soil in insufficient amount and quality to maintain the soil structural stability of the soil. The results of this study showed that lime movement into the deeper soil profile, is very slow, as its impacts are limited to just a few centimeters below of where it is applied or incorporated (2.5 cm after 130 weeks), independent of the applied amount of lime. Thus, the surface lime application intensifies the chemical stratification of the clayey soils under no-tillage, increasing to much the soil pH of the uppermost soil layer, and being inefficient to decrease the soil acidity in the subsurface soil layer. The concentration of lime into the uppermost soil layer can significantly increase the electronegativity of the soil system and result in clay dispersion in the topsoil layer (0 to 5 cm). The resulting clay migration into the soil profile led to a series of structural alterations in subsurface layers, including: decrease of both soil porosity and pore continuity; and increase of both soil bulk density and soil penetration resistance in the sub-superficial layer. The structural stability decreasing of Oxisols under no-till system also is linked with the low addition of organic matter to the cultivated soil, in relation to the non-cultivated soils. The kaolinitic Oxisols are more susceptible to degradation than the gibbsitic Oxisols. Thus, it could be conclude that liming practices (rate and application methods of lime), mainly under no-till systems, need to consider both type and mineralogy of soil, as well as considering soil structure degradation promoted by over-liming in the uppermost soil layer.

Orientadores: Rosa Cristina Cecche Lintz, Luísa Andréia Gachet Barbosa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia
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Resumo: Com a descoberta de aditivos químicos e adições minerais muitos tipos diferentes de concreto surgiram ao longo das últimas décadas. Porém o peso próprio do concreto convencional é considerado a sua maior desvantagem. Com isso abre-se campo para um material que apesar de ser conhecido pelos romanos, era pouco utilizado, o concreto com agregados leves. Muitas pesquisas surgem e em aproximadamente duas décadas aparece o concreto autoadensável e mais recentemente o concreto leve autoadensável. Este trabalho propõe o estudo deste material ainda pouco explorado o concreto leve autoadensável. Para isso são produzidos concretos com argila expandida em duas granulometrias diferentes: uma graúda em substituição total ao agregado graúdo de massa normal e uma miúda em substituição parcial ao agregado miúdo. São elaboradas três famílias de traços de concreto com consumos diferentes de cimento, 320, 360 e 440 kg/m³ de concreto, e realizados ensaios no estado fresco (anel J, funil V e caixa L) e endurecido (resistências à compressão e à tração, determinação do módulo de elasticidade, absorção e densidade). Os concretos leves foram classificados como auto adensáveis e apresentaram bons resultados quanto ao fator de eficiência e resistência sendo possível estabelecer equações de correlação para seu módulo de elasticidade. Para os ensaios de densidade observaram-se concretos leves com massas mínimas de até 1550 kg/m³ e resistências à compressão superiores aos valores estipulados pela norma NBR NM 35 para as densidades apresentadas em todas as misturas
Abstract: With the discovery of admixtures and mineral additions many different types of concrete emerged over the last decades. But the own weight of conventional concrete is considered their biggest disadvantage. With this opens up the field for a material that despite being known to the Romans, it was little used, the concrete with lightweight aggregates. Much research and come in about two decades appears the self compacting concrete and more recently the lightweight concrete self compacting. This work proposes the study of this material still little explored concrete lightweight self compacting. For this are produced concrete with expanded clay in two different particle sizes: one coarse in total replacement of coarse aggregate of normal mass and a fine partially substituting fine aggregate. Are designed three families of concrete mixtures with different cement consumption, 320, 360 and 440 kg / m³ of concrete, and the tests carried out in the fresh state (ring J, V funnel and L box) and hardened (resistance to compression and traction , determining the modulus of elasticity, absorption, and density). The concretes were classified as self compacting and showed good results as to efficiency and resistance factor being possible to establish a correlation equations for its modulus of elasticity. For the density tests were observed concretes with minimum masses of up to 1550 kg / m³ and compressive strengths greater than those stipulated by NBR NM 35 standard for the densities presented in all mixtures
Mestrado
Tecnologia e Inovação
Mestre em Tecnologia

Esta tese aborda as influências do agregado leve na dosagem, características físicas e mecânicas de concreto autoadensável (CAA) quando na fração de graúdo da mistura, substitui-se parte do volume absoluto da brita de basalto (máx 19 mm) pelo volume equivalente de argila expandida brasileira (máx 12,7 mm). O fato de conhecer as implicações na reologia do CAA, provocadas pelo uso conjunto de agregados com características físicas distintas e, apresentar este tipo de concreto como uma alternativa promissora para uso na indústria da pré-fabricação em concreto, justificam esta pesquisa. A substituição da brita de basalto pela argila expandida (AE-1506), em teores de volume absoluto, foi de 20%, 40%, 60%, 80% e 100%. Como resultados, produziram-se concretos autoadensáveis com consumo de aglomerantes (cimento Portland CP V-ARI e sílica ativa) da ordem de 510 kg/m³, que atenderam aos limites de autoadensabilidade propostos pela norma NBR 15823-1 (2010). Na condição endurecida, apresentaram massa específica seca de 2.358,3 a 1.720,7 kg/m³, resistência à compressão (fc28) de 60 a 43 MPa, módulo de elasticidade (Esc) de 23 a 34 GPa e eficiência estrutural (FEE) de 22 a 29 MPa.dm³.kg-1, sem sinais visíveis de frente de carbonatação. Obteve-se concreto leve autoadensável (CLAA) a partir de misturas com fração de graúdo foi composta por 60% de argila expandida e 40% de brita de basalto, que atingiram massa específica seca de 1.986 kg/m³, resistência a compressão (fc28) de 51,3 MPa e condutividade térmica () de 1,07 a 1,53 W/m.K. Constatou-se que a argila expandida interfere significativamente nas características dos concretos exigindo, na comparação com CAA confeccionado com 100% de brita de basalto, maior teor de argamassa e relação volume de água/volume de finos mais elevado.
This thesis discusses aspects related to the influence of lightweight aggregate in the mix design, physical and mechanical properties of the self-compacting concrete (SCC) when replacing part of the absolute volume of basalt crushed stone (máx19 mm) with a lightweight aggregate equivalent absolute volume Brazilian expanded clay (máx 12,7 mm). Understanding interference on the rheology of the SCC caused by the use of aggregates with different physical properties and recommend this type of concrete as a promising alternative for the pre-fabricated concrete industry, justify this research. The replacement of basalt crushed stone for lightweight aggregate (AE-1506), in equivalent absolute volume, was 20%, 40%, 60%, 80% and 100%. As a result, self-compacting concrete was produced with consumption of binders (cement Portland CP V-ARI and silica fume) of about 510 kg / m³, appropriate for self- compactibility limits established by the ABNT NBR 15823-1 (2010) standard. In the hardened condition, the dry density value ranged from 2.358,3 to 1.720,7 kg/m³, compressive strength (fc28) ranged from 60 to 43 MPa, elasticity modulus (Esc) ranged from 23 to 34 GPa, and efficiency structural (FES) ranged from 22 to 29 MPa.dm³.kg-1, with no visible signs of carbonation. The self-compacting lightweight expanded clay concrete (SCLC) was obtained from mixtures which its absolute volume fraction of aggregate coarse was composed by 60% of expanded clay and 40% of basalt crushed stone, with dry density of 1986 kg/m³, compressive strength (fc28) of 51.3 MPa and thermal conductivity () varied from 1,07 to 1,53 W/m.K. It was found that the expanded clay significantly interferes in the properties of concretes demanding in comparison with SCC made with 100% basalt crushed stone, mortar content and ratio higher volume of water/volume of higher fines.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The objective of this work was to modeling runoff in soils with different physical characteristics, with three simulated rainfall intensities (30, 60 and 120 mm h-1) in Rio Grande do Sul and Uruguay. For simulated rainfall was used a portable rainfall simulator of multiple nozzles. Six plots were delimited by metal sheet borders (0,5 m2), with a runoff collector in the lower part. The runoff was determinate each five minutes. On each soil was determinate initial time and rate of runoff, rainfall (total, time and intensities), direction of slope, crop residue and cover percentage, soil densities (bulk and particle), soil porosity (bulk, macro and micro), textural fractions (clay, silt and sand), initial and saturated soil moisture. The runoff was estimated with Smith s modified model. The model parameters were adjusted by multivariate equations. The runoff losses accumulated in Uruguay was 64, 32, 30 e 15% from total rain, for Vertissolo 1, Chernossolo, Argissolo 2 e Vertissolo 2, respectively. The runoff losses accumulated in Rio Grande do Sul was 67, 45 and 27% from total rain, for Argissolo 1, Neossolo e Latossolo, respectively. In most of the cases, the initial runoff time decreased with increasing soil moisture and rain intensity, independently of the soil surface conditions. Smith s modified model estimated better the runoff with high soil moisture. The model adjustment was satisfactory for Rio Grande do Sul.
Com o objetivo principal de modelar o escoamento superficial para solos com diferentes características físicas a partir de diferentes intensidades de precipitação e duração das chuvas, realizaram-se chuvas simuladas em diferentes solos no Rio Grande do Sul e Uruguai, com intensidade de 30, 60 e 120 mm h-1. As chuvas artificiais foram aplicadas utilizando-se um simulador estacionário de bicos múltiplos e oscilantes. Seis parcelas foram delimitadas por chapas metálicas galvanizadas cravadas no solo (0,5m2), contendo na parte inferior uma calha coletora, para coletar a água do escoamento superficial (mensurado em intervalos de cinco minutos). Em cada solo foi determinado o tempo de início e a taxa de escoamento superficial, além da chuva (quantidade, duração e intensidade), declividade do terreno, massa seca na superfície e cobertura do solo, densidade (do solo e de partícula), porosidade do solo (macro, micro e total), textura (argila, silte e areia), umidade inicial e de saturação do solo. Utilizou-se o modelo modificado de Smith para estimativa do escoamento superficial. Os parâmetros do modelo foram ajustados através de equações multivariadas. No Uruguai, as perdas acumuladas por escoamento superficial foram de 64, 32, 30 e 15% do total aplicado, para o Vertissolo 1, Chernossolo, Argissolo 2 e Vertissolo 2, respectivamente. No Rio Grande do Sul, as perdas acumuladas por escoamento superficial foram de 67, 45 e 27% do total aplicado, para o Argissolo 1, Neossolo e Latossolo, respectivamente. Na maioria dos casos houve uma redução no tempo de início de escoamento superficial, com o aumento da umidade inicial do solo e da intensidade da chuva, independentemente das condições da superfície do solo. O modelo modificado de Smith estima melhor o escoamento superficial em condições de elevada umidade do solo e o ajuste foi satisfatório para o Rio Grande do Sul.

Nowadays, efforts are being made to reduce the environmental impact on the planet even at soils management. Excavated soils are treated as waste and often end up in landfill or depot landfills. It is an effort to exploit these soils. By adding suitable stabilizing additives, features such as yield fluidity, moisture or compressive strength can be adjusted. This composite can be further liquefactioned by using water and suitable liquefiers or plasticizers. Such iquefactioned soils are a suitable self-compacting grouts dressing for excavation for the laying of utility grids, where it is necessary to fill the hole again. The advantage are low economic demands and the absence of excess waste. In the course of this thesis the situation of soil usability in the Czech Republic will be evaluated and possible technologies of soil adjusters will be described. Further, the known types of stabilizing additives and their influence on soil stabilization will be evaluated and verified. Then, different types of liquefying additives will be evaluated and verified. The aim of the thesis is to develop a new technology of liquefaction and soil stabilization.

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The search for alternative materials with lower density, reduction in heat transfer and propagation of noise associated with the ease of handling and application in concrete structures, represents an enormous challenge in the formulation and knowledge of the performance of self-compacting lightweight concrete, which has technology little known nationally, and appears on the international scene as an innovative material and alternative to conventional concrete. Based on these, this study set out to study self-compacting lightweight concrete made with two distinct grades of expanded clay associated with the addition of plasticizing/superplasticizers additives and mineral additions of metakaolin and bagasse ash of sugar cane. There is also an object of study, evaluation of pozzolanic activity of mineral admixtures and their influence on the durability characteristics of concrete. The rheological, physical, mechanical and microstructural analysis in this study served as basis in the classification of concretes autoadens?veis, targeting the national technical requirements for their classification in the category autoadens?vel and lightweight structural. The inclusion of mineral admixtures (metakaolin and bagasse ash of sugar cane), partial replacement of cement, pozzolanic activity and demonstrated maintenance of mechanical properties through the filler effect, a reduction of up to 76% of the nitrogen gas permeability in blend with 20% bagasse ash. All concretes had rheology (cohesion and consistency) suitable for self-adensability as well as strength and density inherent structural lightweight concrete without presenting phenomena of segregation and exudation
A busca por materiais alternativos de menor massa espec?fica, redu??o na transfer?ncia de calor e propaga??o do barulho, associado ? facilidade de manuseio e aplica??o em estruturas de concreto armado, representa grande desafio na formula??o e conhecimento do desempenho de concretos estruturais leves autoadens?veis, que tem tecnologia pouco difundida em n?vel nacional, e surge no cen?rio internacional como um material inovador e alternativo ao concreto convencional. Frente ao exposto, este trabalho se prop?s a estudar concretos estruturais leves autoadens?veis elaborados com duas gradua??es distintas de argila expandida associados ? inclus?o de aditivos plastificantes/superplastificantes e adi??es minerais de metacaulim e cinza de biomassa de cana-de-a??car. Tem-se ainda como objeto do estudo, a avalia??o da atividade pozol?nica das adi??es minerais e sua influ?ncia nas caracter?sticas de durabilidade dos concretos. As propriedades reol?gicas, f?sicas, mec?nicas e microestruturais, analisadas neste estudo, serviram como fundamenta??o na qualifica??o dos concretos leves autoadens?veis, visando ?s exig?ncias t?cnicas nacionais para sua classifica??o no quesito autoadens?vel e estrutural leve. A inclus?o das adi??es minerais (metacaulim e cinza de biomassa de cana-de-a??car), em substitui??o parcial do cimento, demonstrou atividade pozol?nica e manuten??o das propriedades mec?nicas atrav?s do efeito filler, apresentando redu??o de at? 76% da permeabilidade a g?s nitrog?nio na mistura com 20% de cinza de biomassa. Todos os concretos dosados apresentaram reologia (coes?o e consist?ncia) adequada para autoadensabilidade, bem como resist?ncia e massa espec?fica inerentes aos concretos estruturais leves, sem apresentar fen?menos de segrega??o e exsuda??o

The thesis is devoted to improving the optimal compaction criteria of road embankment soils, which provide their long-term strength. The first unit contains the analysis of modern soil compaction methods, subgrade deformation causes in the embankment, finite element method (FEM) solves of soil compaction tasks, regulatory framework of quality control disadvantages, and others. The second unit is stated a new author's method and the laboratory tests results of water migration in compacted silty loam embankment, including the stabilized (or final) clay soil moisture values, depending on their type (number plasticity), soil skeleton density, embankment height and time «rest» of the subgrade before it’s operation are presented. Water migration patterns in clay soil, placed in plastic tubes (it is simulated the soil multilayer consolidation of road embankment) through time is researched. In the third unit as a result of statistical processing by least squares method the research laboratory and field data, the empirical dependence of compacted clay soil stabilized moisture for their multilayer consolidation in relation to soil skeleton density and plasticity number values is obtained. Empirical dependence parameter corresponds to maximum molecular moisture capacity at what it is advisable to do the subgrade clay soils multilayer consolidation for their long-term strength ensuring. The embankment thickness of multilayer consolidation and subgrade «rest» time after 2 months did not significantly affect the stabilized soil moisture. In the fourth unit the field observation of clay soils compaction with multilayer rolling at five objects is performed. Full-scale experiment found that multilayer loams moisture consolidation by plastic limit of these soils during the «rest» time after subgrade erection and before its operation is reduced to a maximum molecular moisture capacity. General form of receiving from laboratory tests dependence of compacted loams stabilized moisture for their multilayer consolidation in relation to soil skeleton density in road embankment and plasticity number is approved. The fifth unit contains the FEM modeling correct conditions of clay soils compaction process being a part of road embankments; suggestions for the optimal compaction criteria of road embankment soils; thesis results implementation. With high statistical indicators values the empirical equation of the relationship between clay soil skeleton density in each compacted layer and the initial clay soil skeleton density within the layer after its dumping and leveling, initial thickness of filled and planned to horizontal level subgrade by grader or bulldozer layer, reduction of each clay soil layer surface under the smooth roller is obtained.

碩士
國立臺灣科技大學
營建工程技術學系
86
A full scale field test and a 2-D laboratory model test were adopted to study the compaction grouting induced soil and strength increase for soil around the grout bulb and the ground surface heave - resettlement. A predictive model for evaluating the compaction grouting induced soil strength improvement is proposed based on the test laboratory results. The full scale test indicates that the amount of surface heave is related to the radius of grout bulb (r) and the distance from the injecting point(h). For h = 6.5 r to 20 r, the ground heaves is not much affected by the increase in grout volume nor by the distance from the injecting point. In comparison, for h < 6.5 r, the surface heave becomes larger and the amount of heave increases more significantly as it gets closer to the injection point. When the excess pore-water pressure dissipates, about 1/4 to 1/5 of the ground heave will settle back in a time period of 40 days. The laboratory model test indicates that degree of strength improvement tends to decrease with the distance from the injection point. At a distance more than five to six times the grout bulb diameter, no obvious increase in soil strength was observed. The softer clay, the higher degree of strength improvement can be achieved. The predictive model show that the soil strength improved around the compaction grout bulb increases with the decreasing distance, the increasing void ratio, the decreasing compression index, as well as the decreasing material parameter. The amount of strength increase can be satisfactorily predicted by the proposed model.

As the many constructions activity are to be done in different fields under many government schemes. There is huge need arise to economize the construction cost and cost of material. The subgrade is that part of soil which supports the many types of footing and also carries the load from superstructure. As at every place good quality of subgrade is not available, so there is need to improve the quality of weak subgrade. Either we replace it completely and fill it with good quality of material or improve the engineering property of subgrade by using ad mixer or by using the polymer just like geogrid, geotextiles etc. As the replacement of subgrade is not economical solution when the weak subgrade is presented up to a should have good bearing capacity and other engineering properties which may further economize the cost of construction.As the material chosen for the improvement of subgrade must have appropriate strength itself or in combination with the soil and it must be economical to use and easily available. In the present investigation CBR tests were carried out on sandy and clay soils. With these two types of soils we are also using the geogrid as reinforcement at different positions.Here we are also increasing the surcharge and degree of compaction. Effect on the CBR value is to be observed at increase in surcharge and degree of compaction on reinforced clay and sandy soils. It was reported that with increase in surcharge and degree of compaction CBR value of soil also increased. The optimum result comes out when we use increased surcharge, degree of compaction and geogrid in a single stage.

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A comprehensive experimental programme was performed with the focus on assessing the effects of compaction delay and ambient temperature on the physical, mechanical and hydraulic properties of lime treated expansive clays. Specimens were mellowed for a period of 0, 3, 6, 12, 24 and 48 h at two different temperatures of 20°C and 40°C prior to being compacted, tested and/or cured for up to 28 days for evaluating the impacts on long-term strength development. All specimens were prepared with the same dry unit weight of 12.16 kN/m3 and moisture content of 40% except for tests aimed at determining dry unit weight as a function of mellowing period. The results revealed that as the mellowing duration increased the dry unit weight declined remarkably at both temperature within the first 12 h. In addition, higher reduction rate was observed when specimens were mel-lowed at a temperature of 40°C. A 97% reduction in swelling pressure was obtained when the specimens were compacted upon mixing (zero hour mellowing period) and left to cure for 24 h prior to testing. Permeability coefficient of lime treated expansive clays was increased by up to 40 times when compaction was delayed for 24 h or when specimens were mellowed at 40°C. Specimens mellowed at a temperature of 40°C showed rela-tively stable values of permeability coefficient over the measurement period which could be attributable to accelerated pozzolanic reaction. The Unconfined Compressive Strength tests revealed that strength of lime treated expansive clays is significantly affected by compaction delay. An increase of 234% and 282% in the Unconfined Compressive Strength was achieved after 24 h of mixing with no compaction delay at 20°C and 40°C respectively. Gradual long-term gain in strength was observable within the 28 days post mixing but the rate of strength gain becomes slower and independent of temperature after the first 24 h of mixing. The results sug-gested that the four key reaction mechanisms occur concurrently with the first 12–24 h after lime addition recognized as being the most crucial period of time. Damaging the cementitious compounds by delayed com-paction is harmful to strength and restraining of swelling potential of lime treated expansive clays.

Dissertação de mestrado integrado em Engenharia Civil
De modo a acompanhar as exigências associadas aos projetos de engenharia há uma crescente necessidade de melhorar as características dos solos pois, por vezes, estes na sua forma natural não contêm características satisfatórias para a utilização na construção civil. A reconstituição de provetes em laboratório permite estudar as características dos solos, quer a nível de resistência mecânica e deformabilidade, de forma a promover um conhecimento mais alargado sobre o comportamento dos mesmos quando sujeitos a projetos de Engenharia. A compactação dos solos é o processo utilizado para conferir ao solo, que se encontra na forma natural, melhor características estruturais, ou seja, menor deformabilidade e maior resistência mecânica. O processo de compactação pode ser realizado de diversas formas, sendo que estas podem ou não produzir características estruturais distintas. Neste caso de estudo, o objetivo é perceber a influência da técnica de elaboração de provetes laboratoriais na quantificação da resistência mecânica e deformabilidade do solo. Assim, foram selecionados dois tipos de solo, nomeadamente, um solo residual granítico (incoerente) e uma argila (coerente). Estes dois solos foram compactados por quatro técnicas de compactação distintas: compactação Proctor, compactação com o martelo vibratório, compactação manual e compactação Harvard. Foram realizadas amostras compactadas pelas diferentes técnicas de compactação em estudo, para ensaio na caixa de corte direto e edómetro. Estes dois ensaios permitiram perceber o objetivo deste caso de estudo. Este conhecimento é de extrema importância pois permite verificar qual a sensibilidade dos solos á técnica de compactação aplicada, o que poderá decidir uma atitude diferente enquanto engenheiros civis.
In order to face the demands related to engineering projects, there is an increasing need to improve soil composition since it is usually not appropriate for civil construction in its natural state. Laboratory reconstituted samples make the study of soil features possible both in terms of mechanical resistance and deformation, promoting a deeper knowledge concerning its behavior when used for engineering projects. Soil compaction is the process used to provide natural soil with better structural features. This means less deformation and greater mechanical resistance. The compaction process can be performed in different ways, however these can either produce distinct structural characteristics or not. In this case study, the objective is to understand the influence of the technique used to prepare laboratory samples on the quantification of mechanical resistance and deformation of the soil. Therefore, two types of soil have been selected, namely, residual granite soil (non coherent) and a clay (coherent). These two types of soil have been compacted using four compaction methods: Proctor compaction, vibrating hammer compaction, manual compaction and Harvard compaction. Samples have been made using these different techniques for direct shear box and oedometer testing. These two tests clarified the objective of this case study. This knowledge is paramount in verifying the sensitivity of the soil regarding the compaction method applied, and this can influence the behavior of civil engineers.

Austin, Texas consists of highly expansive soils that have caused failures in many structures. Minimizing the detrimental effects of expansive soils on structures requires that the swelling of these soil(s) is quantified accurately, efficiently, and timely. A testing procedure was developed to directly measure soil swelling using centrifuge technology by Plaisted, 2009. This testing procedure was developed in order to reduce the test duration while generating more swelling data relative to conventional tests that directly measure swell. However, the new procedure was incapable of obtaining in-flight swell data, resulting in the need to develop a procedure to directly measure swell during centrifugation. The objectives of this study were to update the testing procedure developed by Plaisted, 2009 by incorporating the use of an in-flight Data Acquisition System (DAS) that would produce accurate and repeatable results; and use the updated testing procedure to quantify the effects of compaction conditions on swelling for three expansive soils in the Austin area (Eagle Ford Shale, Houston Black Clay, and Taylor Clay). A DAS consisting of linear position sensors, analog to digital converters, JeeNode Arduinos, and an accelerometer was developed and installed within the centrifuge. Specimens were compacted at various water contents, and densities, and subjected to different g-levels. The effects of g-level, compaction water content, compaction dry unit weight, and soil type were determined by comparing the 34 hour swell percentages for the compacted specimens. The results of this study showed that in-flight monitoring of clay swelling could be successfully implemented in a comparatively small centrifuge, and that the data collected from the DAS was accurate and repeatable. Swelling of tested soils was found to be sensitive to changes in water content around optimum, with specimens compacted wet of optimum swelling less than specimens compacted dry of optimum. A 6% increase in relative compaction was found to negligibly affect the swelling. Finally, variations in confinement and compaction conditions were found to have a greater effect on swelling for soils that are more expansive in nature compared to soils less expansive in nature.
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