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Approaches to mix design and measurement of workability for self-compacting concrete.Jooste, Josef Petrus 28 February 2007 (has links)
Student Number : 0218148W -
MSc Dissertation -
School of Civil Engineering -
Faculty of Engineering and the Built Environment / Self-compacting concrete (SCC) is becoming a popular form of concrete usage in
a range of applications throughout the world. This investigation considers the
development of the technology and use of SCC. Importantly, the investigation
aims to highlight the opportunities for using SCC in South Africa. A mixture
design model is proposed and has been found to work well using local materials.
The advantage of this model is the simplicity and the adaptability to any aggregate
type. This method should be more acceptable to SCC producers who do not have
special facilities and testing equipment
An overview concerning concrete rheology is included to explain the mechanisms
used to describe the flow and deformation of both the concrete and mortar
mixtures. Included is a comparison between concrete, mortar and paste rheology.
The Tattersall Two Point Tester was used to measure the shear resistance at two
shear deformation rates.
From the test results it was found that SCC can be made using South African
materials and that it is possible to design a mixture with a lower cementitious
content. The results from the Tattersall Two Point Tester gave additional
information about the flowability of SCC.
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PREDICTION OF 28-DAY COMPRESSIVE STRENGTH OF CONCRETE USING RELEVANCE VECTOR MACHINES (RVM)Owusu Twumasi, Jones 01 May 2013 (has links)
Early and accurate prediction of the compressive strength of concrete is important in the construction industry. Modeling the compressive strength of concrete to obtain a balance and equality between prediction accuracy, time and uncertainty of the prediction is a very difficult task due to the highly nonlinear nature of concrete. For structural engineering purposes, the 28- day compressive strength is the most relevant parameter. In this study, an attempt has been made to predict the 28-day compressive strength of concrete using Relevance Vector Machine (RVM). An RVM belongs to the class of sparse kernel classifiers, which are powerful tools in classification and regression. It has a model of identical functional form to the popular and state-of-the-art `Support Vector Machine (SVM)'. The benefits of using RVM include automatic estimation of nuisance parameters, probabilistic prediction and the ability to model complex data with little information. A total of 425 different data of high performance mix designs were collected from the University of California, Irvine repository. The data used to predict the compressive strength consisted of nine components. The RVM model was trained and tested using 395 and 30 data sets respectively. The model's performance was assessed at the end of the training and testing period using four performance measures; coefficient of determination, root-mean-square error, percentage of relevance vectors and residual plots. All the performance measures confirmed the accuracy of the model. The results of the study suggested that RVM is an effective tool for predicting the 28- day compressive strength of concrete from its mix ingredients.
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Factors Affecting Strength Gain and Development of a Laboratory Testing ProcedureJacobson, Jesse Richard 09 May 2002 (has links)
Lime-cement columns were constructed to improve soft ground at the I-95/Route 1 Interchange in Alexandria, Virginia. As part of the test embankment program, two different commercial laboratories performed laboratory tests on treated soil, and they produced strikingly different unconfined compression test results. Further, both sets of results are different from test results for similar soils available in the published literature. This situation created uncertainties and a conservative design philosophy, accompanied by increased construction costs compared to typical lime-cement column projects. The goals of this research project were to assess factors that influence strength gain of lime-cement-soil mixtures and to develop a detailed laboratory test procedure that produces consistent results. Key findings from the research are that a laboratory test procedure that produces consistent results has been developed, drying and subsequent restoration of soil moisture prior to treatment can decrease the strength of the mixture, the mixture strength decreases as the ratio of soil water content to cement content increases for 100 percent cement-soil mixtures, the addition of lime can increase the mixture strength for some soils and decrease the strength for others, and presenting the test results in the form of contour plots of unconfined compressive strength can be very useful. / Master of Science
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Characterisation of material properties and behaviour of cold bituminous mixtures for road pavementsEbels, Lucas-Jan 03 1900 (has links)
Thesis (PhD (Civil Engineering))--Stellenbosch University, 2008. / The cold bituminous mixtures, which are the subject of this study, are obtained by
mixing mineral aggregate with either bitumen emulsion or foamed bitumen at
ambient temperatures. These techniques are frequently used in Cold In-Place
Recycling whereby typically the top 150 – 250 mm of the existing pavement is
reworked, as a rehabilitation measure when structural maintenance is required. To
differentiate from the cold mixes for surfacing layers the term Bitumen Stabilised
Materials (BSM’s) is adopted here.
The increased use of BSM’s, shortcomings in the existing design guidelines and
manuals and ongoing developments in the concepts and understanding of these
materials require further research into the fundamental properties and behaviour of
BSM’s. Achieving a better understanding of the fundamental performance properties
of BSM’s is the main objective of this study, with a view to using the extended
knowledge for improvements to current mix design and structural design practices.
The state-of-the-art of bitumen emulsion and foamed bitumen techniques is reviewed
in a literature study. Current best practices in the design of BSM’s and pavements
incorporating such materials is also included in this literature study. Shortcomings
and areas for further improvement of the design practice have been identified. With
new environmental legislation that recently came into effect in South Africa, the
importance of BSM technology as an environmentally-friendlier and more
sustainable construction technique is set to increase in the coming years.
A laboratory testing programme was set-up to study the properties and behaviour of
BSM’s and to establish links with the compositional factors, i.e. the type of binder
used, the percentage of Reclaimed Asphalt Pavement (RAP) in the mix and the
addition of a small dosage of cement as active filler. The mineral aggregates used
were sourced in the USA and consisted of crushed limestone rock and RAP millings.
These were blended in two different proportions of crushed rock : RAP, i.e. 3:1 (with
3.6 % residual binder) and 1:3 (with 2.4 % residual binder). Tri-axial testing
(150 mm diamter) was carried out to determine shear parameters, resilient modulus
and permanent deformation behaviour, while four-point beam testing was carried out
to determine strain-at-break, flexural stiffness and fatigue behaviour.
It was found that the process of bitumen stabilisation improves the shear strength of
the material, particularly in case 1 % of cement is added as active filler. This increase
in shear strength is entirely the result of increased cohesion. There is a good
correlation between the shear strength and the resilient modulus of BSM’s. The
resilient modulus of BSM is stress-dependent and the Mr-θ model is adequate to
model the resilient modulus of the blends with a low percentage of RAP. For the
blends with a higher percentage of RAP this model cannot be applied and the
resilient modulus reduces in stiffness at higher deviator stress ratios.
A considerable part of the efforts of this study were dedicated to characterise and
model the permanent deformation behaviour. The General Permanent Deformation Law as originally developed by Francken applies also to BSM’s. An improved nonlinear
method to converge at a solution for the model parameters that describe the
tertiary flow part of this deformation law was developed as part of this study.
Parameters that can be derived from the first stage of the permanent deformation test,
i.e. initial strain and initial strain rate as defined in this study, were found that
correlate well with the model parameters that describe the first linear part of the
deformation law. Critical deviator stress ratios for the several mixes tested were
determined. When BSM’s are subjected to loading below these ratios, tertiary flow is
unlikely to occur.
A high variability was generally found in the four-point beam test results, especially
for the strain-at-break. Specimen preparation protocols and the quality of the beam
specimens are of utmost importance when performing four-point beam tests on
BSM’s. This limits the practical applications of the strain-at-break test. Trends
observed in the strain-at-break were also inconsistent and sometimes not in line with
the other type of tests.
BSM’s exhibit a visco-elastic behaviour, which was determined by flexural stiffness
testing, however, to a lesser extent than HMA. Phase angles and Black Diagrams
were developed for the BSM’s tested, which also made it possible to determine the
parameters of the Burgers Model, which is a mechanical model describing viscoelastic
behaviour. Fatigue relationships were also developed for the BSM’s tested.
The fatigue performance of these mixes is lower than for selected HMA mixes. The
foamed BSM generally showed better fatigue life than emulsion BSM, however, the
lower initial stiffness of the foamed BSM’s may contribute to a perceived longer
fatigue life. For the mixes tested, the flexural stiffness of foamed BSM’s is generally
also lower than that of emulsion BSM’s
It is recommended that the mix design of BSM’s be split into two phases. During the
first phase the usually large number of variables could be reduced to a selected few
by means of UCS and ITS indicator testing. Subsequently, more fundamental
parameters should be determined during the second phase, such as shear strength and
resilient modulus, as well as permanent deformation behaviour. The fact that
commercial laboratories in South Africa do not have tri-axial testing facilities is
currently a practical limiting factor. Initiatives currently underway to develop
“simple” shear tests are welcomed in this regard. It is proposed that classification of
BSM is based on shear strength.
There are indications that shear failure in BSM is more critical than failure as a result
of fatigue. The effect of curing resulting in an increase in BSM stiffness in the period
after construction, i.e. typically 6 to 18 months, is currently ignored in structural
design models. The rapid stiffness reduction of BSM’s during the first period after
construction in the current structural design models and also found during
Accelerated Pavement Testing is not being observed in Long-Term Pavement
Performance (LTPP). On the contrary, an increase in stiffness is observed in LTPP.
This would indicate that stiffness reduction as a result of fatigue does not occur or is
overshadowed by the effect of curing and that fatigue as a failure mechanism of
BSM’s is currently over-emphasized.
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An investigation into some aspects for foamed bitumen technologyNamutebi, May January 2016 (has links)
Despite applications of foamed bitumen technology in pavement construction in various places around the world, there are still several aspects about this technology that are not clear. In addition, knowledge on foamed bitumen technology is mainly empirical and lacks scientific basis. This study addresses some of the aspects for foamed bitumen technology such as: Investigation of any effects in binder composition during the production process for foamed bitumen; assessment of the effect of bitumen source on foamed bitumen characteristics; development of a rational method to optimise foamed bitumen characteristics and conditions; evaluation of aggregate particle coating within foamed bitumen mixes; further improvements in the mix design procedure specifically the method of compaction and optimum bitumen content determination stages are suggested. Fourier transform infrared spectroscopy techniques were used to investigate any changes in bitumen composition after the production process of foamed bitumen. Fourier transform infrared tests were done on foamed bitumen and neat bitumen specimens for two bitumens with similar penetration grades. Foamed bitumen characteristics of three bitumens were established by producing foamed bitumen at temperatures of 150ºC up to 180ºC and foamant water contents of 1, 2, 3, 4 and 5%. From the analysis of variation of foamed bitumen characteristics (maximum expansion ratio and half-life) at different temperatures a new method based on the equi-viscous bitumen temperature to optimize foamed bitumen conditions and characteristics was proposed. Rice density and surface energy concepts were used to evaluate aggregate particle coating with foamed bitumen. A granite aggregate divided into three different size fractions and three sets of foamed bitumen produced from three bitumen penetration grades were used. A gyratory laboratory compaction procedure for laterite gravels treated with foamed bitumen was established using the modified locking concept. Three laterite gravels with different chemical composition were mixed with foamed bitumen produced from one penetration bitumen grade. The resulting mixes were compacted up to 200 gyrations and the corresponding compaction curve defined in terms of height versus number of gyrations noted. In addition, the optimum moisture content requirements at the modified locking point were determined. 3D packing theory concepts, primary aggregate structure porosity and an indirect tensile strength criteria were employed to determine optimum bitumen content for foamed bitumen mixes. Fourier infrared techniques revealed that foaming did not cause any changes in the bitumen chemistry, implying that the foamed bitumen production process may possibly be a physical process. Characterisation of foamed bitumen produced from three bitumen penetration grades showed that foamed bitumen characteristics (maximum expansion ratio and half-life) were mainly influenced by binder viscosity rather than the source. The equi-viscous temperature seemed to provide a suitable criterion at which foamed bitumen with optimum characteristics could be produced. Rice density results showed that aggregate size fraction, binder expansion ratio and viscosity influenced aggregate particle coating. For the coarser aggregate fraction, results revealed that binder coating seemed to be mainly influenced by temperature. Whilst for fine aggregate fraction the coating was mainly influenced by surface area. Surface energy results revealed that foamed bitumen exhibited better coating attributes than neat bitumen. A new laboratory compaction procedure for laterite gravels treated with foamed bitumen based on the modified locking point was developed. The modified locking point represents the state at which maximum aggregate particle interlock occurs when mixes are compacted in the field. It is based on the iii analysis of the rate of change for the gyratory compaction curve. The compaction curve in this case is defined in terms of compaction height versus number of gyrations. Gradation analysis beyond the modified locking point showed that aggregate particle breakdown occurred. Analysis of the optimum moisture at the modified locking point revealed that the moisture conditions were less than the aggregate optimum moisture conditions. It is recommended that this point be used to determine the optimal compaction characteristics of foamed bitumen mixes. Aggregate structure porosity and an indirect tensile strength criteria can be used to determine the bitumen content that could be used in design of foamed bitumen mixes. This would reduce the amount of resources required since the bitumen content could be estimated prior to carrying out the actual laboratory work given that the aggregate grading is known. The aggregate structure can be divided (based on 3D packing theory) into oversize, primary, and secondary structures. The primary structure is mostly responsible for carrying loads whilst the secondary structure fills the voids within the primary structure and provides support to the primary structure. The aggregate size particles constituting the primary structure are deduced as a function of standard sieve sizes using the packing theory concepts. The minimum sieve size for the primary structure is proposed as 1 mm. The oversize structure consists of aggregate particles whose size is greater than the maximum size for the primary structure. The secondary structure consists of aggregate particles whose size is below the minimum size for the primary structure. The primary aggregate structure porosity can be used to establish the starting bitumen content; the bitumen content at which this porosity is 50% is chosen as the initial bitumen content. Indirect tensile strength values corresponding to 50% primary porosity are determined as well as the bitumen contents and compared against the recommended minimum values. / <p>QC 20161012</p>
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Aplicação do conceito de empacotamento de partículas na otimização de dosagem de concretos de cimento Portland / The application of particle packing concept in the optimization of Portland cement concretes mix designLopes, Herbert Medeiros Torres 26 April 2019 (has links)
O concreto é o material de construção mais utilizado e nos últimos anos, estudos têm sido desenvolvidos em busca de materiais com desempenho mecânico e durabilidade superiores, com redução do consumo de cimento. Nesse contexto, tem-se o estudo do empacotamento de partículas associado à dosagem de concretos, produzindo estruturas mais densas e compactas, com melhor consumo energético. Basicamente, o empacotamento de partículas consiste em otimizar composições empregando partículas de diferentes tamanhos, promovendo o refinamento dos poros e, eventualmente, reduzindo o volume de pasta necessário para envolver as partículas da mistura. O empacotamento de partículas permite uma evolução nas propriedades do concreto, além de promover um benefício ambiental por meio da utilização de resíduos e subprodutos industriais, redução de emissões poluentes e economia de energia, mediante a redução do consumo de cimento na mistura. Diante disto, o presente trabalho tem por objetivo aplicar o conceito de empacotamento de partículas na otimização de traços de concretos convencionais e de alta resistência. Para isso, realizou-se inicialmente um estudo de dosagem, sendo determinados traços de referência pela metodologia tradicional. Aplicando o modelo de empacotamento de Alfred, foi determinado o coeficiente de distribuição de cada mistura e, então, os traços foram otimizados mantendo-se o mesmo coeficiente, sendo comparadas as propriedades dos concretos otimizados com propriedades das misturas de referência. Verificou-se que nas misturas otimizadas não foi possível obter a trabalhabilidade desejada, sendo necessário ajustar o teor de aditivo a fim de manter a mesma consistência. No estado endurecido, os concretos otimizados apresentaram desempenho físico e mecânico superior aos concretos dosados pela metodologia tradicional. Os ensaios não destrutivos apenas permitiram verificar a evolução com o tempo do módulo de elasticidade dinâmico e da porosidade, visto que a mudança da composição das misturas influencia diretamente no módulo e na velocidade de propagação da onda no material. Por fim, foi possível verificar a sustentabilidade dos concretos otimizados, que apresentaram índice de intensidade de ligante mais eficiente que os concretos de referência, reforçando a importância desse trabalho. / Concrete is the most widely used construction material and in recent years, studies have been developed in search of materials with higher mechanical performance and durability, with reduced cement consumption. In this sense, the study of particle packing associated to the mix design of concrete, producing denser and more compact structures, with better energy consumption, is being studied. Basically, particle packing consists of optimizing compositions employing particles of different sizes, promoting pore refinement and possibly reducing the volume of cement paste required to involve the particles in the mix. The particle packing allows an evolution in concrete\'s properties, besides promoting an environmental benefit using industrial wates and by-products, reduction of polluting emissions and energy saving, by reducing the consumption of cement in the mix. In this view, the present research aims to apply the concept of particle packing in the optimization of conventional and high strength concretes mix design. For this, a mix design study was carried out initially, being determined reference concretes mix design by the traditional methodology. Applying the Alfred\'s packing model, the distribution coefficient of each mix was determined and concretes mix design were optimized by keeping the same coefficient, and the properties of the optimized concretes were compared with the properties of the reference mixtures. It was verified that, in optimized mixtures, it was not possible to get the desired workability and it was required to fit the chemical admixture content in order to keep the same consistency. In the hardened state, the optimized concrete showed physical and mechanical performance higher than concretes designed by the traditional methodology. The non-destructive tests only allowed to verify the evolution of the dynamic elasticity modulus and the porosity with time, since the change of the composition of the mixtures directly influences the modulus and the wave propagation speed in the material. Finally, it was possible to verify the sustainability of the optimized concretes, which presented a binder intensity index more efficient than the reference concrete, reinforcing the importance of this research.
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Mix Design and Impact Response of Fibre Reinforced and Plain Reactive Powder ConcreteGao, Xiang, S3090502@student.rmit.edu.au January 2008 (has links)
Concrete is the most broadly used material in construction worldwide and Reactive Powder Concrete (RPC, a type of ultra high performance concrete) is a relatively new member of the concrete family. In this work the critical parameters of RPC mix design are investigated and the mix design is explored through a program of concrete casting and testing. Owing to the enhanced microstructure of RPC, porosity and permeability can be significantly decreased in the concrete matrix. This benefits the durability characteristics of RPC elements resulting in a longer service life with less maintenance costs than conventional concrete. It has been used for high integrity radiation waste material containers because of its low permeability and durability. Fibre reinforced RPC is also ideal for use in long span and thin shell structural elements without traditional reinforcement because of its advantageous flexural strength. Moreover, due to improved impact resistance, RPC can be widely employed in piers of bridges, military construction and blast protection. There is no standard approach to assessing the impact resistance of concrete. This investigation utilises relatively well accepted impact equipment to evaluate the mechanical properties of RPC under dynamic loading. The compressive and flexural tensile strengths of plain and fibre reinforced RPC are investigated using a variety of specimens and apparatus. The dynamic increase factor (DIF) is evaluated to indicate the strain rate sensitivity of the compressive and flexural strength.
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El Rol físico del agua en mezclas de cemento PortlandSoares Klein, Nayara 26 October 2012 (has links)
Water is one of the fundamental components of concrete, not only for its role on the hydration of Portland cement, but also because of the physical functions it develops, which are associated with the main phases of concrete life: fresh state, hardened state and the useful life of the structures.
The objective of this PhD Thesis is to study in detail the physical role of water in Portland cement mixtures: the aggregate absorption, the wetting and the fluidization of the granular skeletons that compose the cement pastes. The study covers the mathematical modelling of the mentioned physical functions in a way that it is possible to calculate the volume of water necessary to perform such functions, facilitating the mix-design process. The calculated volume is considered to be the total volume of water needed for production. Moreover, the calculation must take into account the conditions and constraints associated with the production and casting, as well as the technical requirements of the material to be designed.
The modelling of the water physical functions allowed the development of a calculation method to quantify the approximate volume of water needed for concrete production. The developed method was used to calculate the volume of water of three different special concretes: a lightweight self-compacting concrete reinforced with fibres, an ultra-high performance concrete reinforced with steel fibres and a concrete with recycled aggregates. What is more, the volume of water for two conventional concretes, with compressive strengths of 25 and 30 MPa, was calculated. Since the calculation was based on granular skeletons for real mixtures, produced in laboratory or/and industrially, the results obtained through the use of the developed method were compared to the experimental results of each concrete. At last, the method was used to quantify the volume of paste necessary for the production of a porous concrete.
The results show that the mathematical models used to describe the physical phenomena of absorption, wetting and fluidization fit well to the experimental reproduction of these phenomena. Corrections are needed in some situations due to the ideal boundary conditions adopted during modelling, which facilitate calculation. Anyhow, the errors are corrected through the use of adjusting coefficients. Therefore, the calculation method developed has proven itself effective and applicable in the mix-design of different types of conventional and special concretes, showing the potential to be used for the development of new materials. / El agua es uno de los componentes fundamentales del hormigón, no sólo por ser necesaria a la hidratación del cemento Portland, sino que también por las diferentes funciones físicas que desarrolla, las cuales están asociadas a las principales fases de la vida del hormigón: estado fresco, estado endurecido y vida útil de la estructura.
El objetivo de la presente Tesis Doctoral es realizar un estudio detallado de las funciones físicas del agua en las mezclas de cemento Portland: la absorción de esta por los áridos, el mojado y la fluidificación de los conjuntos granulares que componen las pastas de cemento. Dicho estudio se traduce en la modelización matemática de las funciones físicas presentadas, en el sentido de dar una respuesta numérica que facilite el diseño de mezclas, acotando el volumen de agua necesario al desarrollo de las funciones especificadas, siendo éste el volumen de agua total necesario a la producción. Asimismo, el cálculo del referido volumen debe tener en cuenta los condicionantes de producción, puesta en obra, así como los requerimientos técnicos del material que se va diseñar.
A través de la modelización de las funciones físicas del agua consideradas, se ha desarrollado un método de cálculo para acotar el volumen de agua total necesario a la producción de hormigones. Se ha utilizado el método desarrollado para el cálculo del volumen de agua de tres hormigones especiales distintos: hormigón ligero autocompactante con fibras, hormigón de ultra-alta resistencia reforzado con fibras de acero y hormigón con áridos reciclados. Asimismo, se ha calculado el volumen de agua para dos hormigones convencionales, de resistencias à compresión 25 y 30 MPa. Se han contrastado los resultados obtenidos por el uso del método desarrollado con los resultados experimentales de cada hormigón, ya que el cálculo se hizo con base en conjuntos granulares de mezclas reales, producidas en laboratorio y/o industrialmente. Por último, se ha utilizado el modelo desarrollado para la cuantificación del volumen de pasta necesario a la producción de un hormigón poroso.
Los resultados demuestran que los modelos matemáticos utilizados para describir los fenómenos físicos de absorción, mojado y fluidificación se adecuan bien a la reproducción experimental de dichos fenómenos, en que correcciones son necesarias en algunas situaciones, debido a la adopción de condiciones de contorno ideales en la modelización, que facilitan los cálculos. De cualquier modo, los errores se corrigen a través de coeficientes de ajuste. Así, el método de cálculo desarrollado para acotar el volumen de agua se ha demostrado eficiente en el diseño de diferentes tipos de hormigones convencionales y especiales, pudiendo ser utilizado en el desarrollo de nuevos materiales.
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Aggregates in Concrete Mix DesignGhasemi, Yahya January 2017 (has links)
The importance of studying the behaviour and properties of concrete can be highlighted by considering the fact that concrete is the most used man-made material in the world. The very first step in making concrete is its mix design and deciding the type and amount of constitutes used in the production of concrete which should fulfil the requirements of the final product. Mix design models are commonly used for the purpose of proportioning concrete ingredients while anticipating the properties of the final product. The current document deals with the commonly used principals in mix design models namely particle packing theory and excess water/paste layer theories. The conducted studies includes an investigation on accuracy of particle packing models (Toufar, 4C, CPM) and also tries to address the issue with measurement of specific surface area of particles as an essential input to water/paste layer theories. It has been observed that the particle packing models can predict the packing density with acceptable margin. However, it should be mentioned that the particle packing models by themselves are not mix design models but should be rather used as a part of a mix design. In addition, it was found that the accuracy of calculating the specific surface area of particles based on their size distribution curve can be further improved by assuming angular platonic solids as uniform shape of aggregate instead of traditional approach of assuming spheres for aggregates’ shape.
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Reciclagem de pavimentos com adição de cimento Portland : definição das bases para um método de dosagem / Full-depth reclamation of pavements with Portland cement: Setting the basis for a mix design methodFedrigo, William January 2015 (has links)
A reciclagem profunda com adição de cimento Portland é uma técnica de recuperação estrutural e funcional de pavimentos empregada há muitos anos no país, devido a vantagens técnicas, econômicas e ambientais. Contudo, a difusão mais ampla da técnica esbarra na carência de normas e procedimentos nacionais, o que resulta na adoção de variados critérios nos projetos que incluem reciclagem com cimento, às vezes, comprometendo sua eficácia. A pesquisa relatada nesta dissertação teve por objetivo principal estabelecer as bases para a proposição de um método de dosagem para reciclagem de pavimentos com adição de cimento, considerando-se como referência o método de dosagem de materiais estabilizados com cimento da Austroads (2002). Para verificar a validade deste método para materiais de pavimentos brasileiros, desenvolveu-se um programa experimental no qual foram avaliadas propriedades mecânicas (resistência, rigidez e erodibilidade) e volumétricas (retração, absorção, expansão e ascensão capilar) de misturas constituídas por fresado asfáltico, brita graduada e cimento, variando-se a porcentagem de fresado (20% e 50%), o teor de cimento (2%, 4% e 6%), a energia de compactação (Intermediária e Modificada) e o tempo de cura dos corpos de prova (3, 7 e 14 dias). Os resultados dos ensaios mostraram que todas as variáveis analisadas afetam significativamente a resistência à compressão simples, a resistência à tração por compressão diametral e o módulo de resiliência das misturas, enquanto que a retração, a erodibilidade, a absorção, a expansão e a ascensão capilar são afetadas por algumas das variáveis independentes. Dentre outras conclusões, destaca-se que são obtidos elevados valores de resistência à compressão simples (1,61 MPa a 6,08 MPa), resistência à tração por compressão diametral (0,29 MPa a 1,00 MPa) e de módulo de resiliência (10390 MPa a 25719 MPa) com teores baixo (2%) e médio (4%) de cimento, sendo desnecessário e arriscado, pela elevada retração associada, o emprego de teor mais elevado (6%). Ainda, observou-se que o aumento da energia de compactação permite compensar a utilização de teores mais baixos de cimento no que se refere às resistências (à compressão, à tração e à erosão) e módulos obtidos. Globalmente, conclui-se que o método de dosagem de materiais estabilizados com cimento da Austroads (2002) pode ser usado como modelo para o desenvolvimento de um método de dosagem para reciclagem de pavimentos com adição de cimento, sendo necessárias pequenas complementações ou adaptações. O método de dosagem sugerido nesta Dissertação é, ao mesmo tempo, simples o suficiente para ser empregado em laboratórios de canteiros de obra e amplo o bastante para identificar as propriedades mecânicas e volumétricas que devem ser avaliadas ao elaborar-se um projeto de mistura reciclada com cimento. / Full-depth reclamation (FDR) with Portland cement is a technique used for structural and functional rehabilitation of pavements and has been used in Brazil for many years, especially because its technical, economical and environmental advantages. However, a larger diffusion of the technique has been inhibited by the lack of national standards and procedures, resulting in the adoption of different design criteria, which sometimes leads to a low efficiency of the FDR with cement. This research was carried out with the objective of setting the basis for a mix design method for FDR with cement, considering the Austroads (2002) mix design method for stabilized pavement materials as a model. In order to verify the applicability of the Austroads method to Brazilian pavement materials, an experimental program was carried out testing mechanical (strength, stiffness and durability) and volumetric (drying shrinkage, absorption, swell and capillary rise) properties of mixtures made of reclaimed asphalt pavement (RAP), graded crushed stone and cement. Specimens with different RAP contents (20% and 50%), cement contents (2%, 4% and 6%), compacted with two different efforts (Brazilian Intermediate and Modified) were cured for 3, 7 and 14 days. Test results showed that all the studied variables affect the unconfined compressive strength, indirect tensile strength and resilient modulus of the mixtures, while drying shrinkage, erodibility, absorption, swell and capillary rise are affected by some of the independent variables. Among other conclusions, it is pointed out that high values of unconfined compressive strength (1,61 MPa to 6,08 MPa), indirect tensile strength (0,29 MPa to 1,00 MPa) and resilient modulus (10390 MPa to 25719 MPa) may be achieved with low (2%) and intermediary (4%) cement contents, thus making the use of higher (6%) cement content unnecessary and unsafe, due to the higher costs and to the drying shrinkage associated. It was also observed that increases in the compaction effort may compensate the use of lower cement contents as regards to strengths and moduli obtained. Generally, can be concluded that the Austroads (2002) mix design method for stabilized pavement materials may be used as a model for the development of a mix design method for FDR with cement, being necessary only a few additions or adaptations. The suggested method is, simultaneously, simple enough to be used in field laboratories and comprehensive enough for including the mechanical and volumetric properties that must be evaluated when designing a mix for FDR with cement.
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