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COMPORTAMENTO DE PEQUENAS PAREDES DE ALVENARIA ESTRUTURAL FRENTE A ALTAS TEMPERATURAS / BEHAVIOR OF SMALL STRUCTURAL MASONRY WALLS FRONT OF HIGH TEMPERATURESRigão, Alessandro Onofre 13 August 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The current civil building use several kinds of materials for fencing as solid or
hollow bricks or closure function and structural like the structural masonry. The codes
and national laws of fire protection define a minimum period of fire resistance for
walls and sealing elements. However, the great majority of the codes offer few
alternatives of materials and thicknesses to define the minimum capacity for fire.
Normally in the suggested alternatives, when tested, the materials exhibit superior
performance. The alternative to a proper definition of time of fire resistance is testing
a prototype of the wall in real scale, usually being expensive test. The purpose of this
paper is to study the behavior of structural masonry walls and its components against
high temperatures using furnances adapted to this end. It was studied the level of
degradation of the materials singly and within the set, the increasing of load in small
walls due to the temperature rising, besides the residual strength of the masonry and
its constituents after exposure the high temperatures. The rate of heating of the oven
did not follow Standard Curve, even so, it was possible to verify which the laws are
conservative in relation to the performance against high temperatures of the
materials. The walls obtained good performance against high temperatures, showing
low cracking level and maintaining the structural stability. It was tested mortars with
various resistances to temperature of 900ºC, seeing that this temperature was
sufficient to promote the complete deterioration of materials. Mortars of 4 MPa were
heated to 400ºC, noting that remained intact, showing residual strength. It was
observed that the type of aggregate used in mortars affect the weight loss and
stability of the material when subject to high temperatures. It was molded ceramics
prisms with mortar of 4 MPa to verify the residual strength after heating to 400º and
900ºC, noting that the strength these was higher than average for the same strength
of mortars subjected to the same heating. In addition, failure stress of the small wall
exposed the high temperatures was very close to the average of the ceramic prisms
subjected to the same heating rate. / A construção civil atual utiliza diversos tipos de materiais para vedação como
tijolos cerâmicos vazados ou maciços ou com função de fechamento e estrutural
como a alvenaria estrutural. Os códigos e legislações nacionais de proteção contra
incêndio definem um tempo mínimo de resistência ao fogo para paredes e
elementos de vedação. Entretanto, a maioria desses códigos oferece poucas
alternativas de materiais e espessuras mínimas para definir a capacidade de
resistência ao fogo. Normalmente nas alternativas sugeridas, quando ensaiados, os
materiais apresentam desempenho superior. A alternativa para a definição
adequada do tempo de resistência ao fogo é ensaiar um protótipo da parede em
escala real, sendo um ensaio geralmente dispendioso. A proposta deste trabalho é
efetuar o estudo do comportamento de paredes de alvenaria estrutural e seus
componentes frente a altas temperaturas, utilizando fornos adaptados para essa
finalidade. Foi estudado o nível de degradação dos materiais isoladamente e no
conjunto, o aumento de carga em pequenas paredes devido à elevação da
temperatura, além da resistência residual da alvenaria e seus constituintes após
exposição às altas temperaturas. A taxa de aquecimento do forno não seguiu a
Curva Padrão de norma, mesmo assim, foi possível verificar que as legislações são
conservadoras em relação ao desempenho frente ao fogo dos materiais. As paredes
obtiveram bom desempenho frente às altas temperaturas, apresentando nível de
fissuração baixo e mantendo a estabilidade estrutural. Foram ensaiadas argamassas
de diversas resistências à temperatura de 900ºC, constatando que esta temperatura
foi suficiente para promover a completa deterioração dos materiais. Argamassas de
4 MPa foram aquecidas a 400ºC, observando que mantiveram-se íntegras,
apresentando resistência residual. Foi constatado que o tipo de agregado usado nas
argamassas tem influência na perda de massa e estabilidade do material quando
submetido a altas temperaturas. Foram moldados prismas cerâmicos com
argamassa de 4 MPa para verificar a resistência residual após o aquecimento a 400º
e 900ºC, constatando que a resistência desses foi superior a resistência média para
as argamassas de mesma resistência submetidas ao mesmo aquecimento. Além
disso, a tensão de ruptura da pequena parede exposta às altas temperaturas ficou
bem próxima à média dos prismas cerâmicos submetidos à mesma taxa de
aquecimento.
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Reação álcali-agregado: influência da granulometria do agregadoSilva, João Ricardo Pereira da 25 November 2015 (has links)
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Previous issue date: 2015-11-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Modeling studies the RAA expansion are generally limited by the difficulty due to the heterogeneity and reactive aggregate size range. This work aims to study the issue and help in developing models to predict the potential for expansion of mortar and concrete containing reactive
aggregates. The paper presents measurements to provide experimental data on the effect of aggregate size expanding mortar bars. The results show that expansion was measured on mortars relating the standard from 2.4 to 0.15 mm fraction with the individual fractions 2.4;
1.2; 0.6; 0.3; 0.15 mm, where 0.3 mm fraction showed the highest growth and the lowest was the fraction 0.15 mm. You can observe the interference of particle sizes. The effect size of reactive aggregates is evaluated and the consequences of accelerated laboratory tests are discussed. / Os estudos da expansão RAA são geralmente limitados pela dificuldade devido à heterogeneidade e faixa de tamanho de agregados reativos. Este trabalho tem o objetivo de estudar o assunto e ajudar no desenvolvimento de modelos para prever o potencial de expansão da argamassa e do concreto que contém agregados reativos. O trabalho apresenta medições a fim de fornecer dados experimentais sobre o efeito do tamanho do agregado na expansão em barras de argamassa. Os resultados mostram que a expansão medida nas argamassas relacionando a fração padrão 2,4-0,15 mm com as frações individuais 2,4; 1,2; 0,6; 0,3; 0,15 mm, onde a fração 0,6 mm apresentou a maior expansão e a menor foi à fração 0,15 mm. É possível observar
a interferência das faixas granulométricas. O efeito do tamanho dos agregados reativos é avaliado e as consequências sobre os ensaios laboratoriais acelerados são discutida.
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Reducción de la deformación permanente en pavimentos diseñados con mezclas asfálticas en caliente a través de la incorporación de polvo de caucho proveniente de neumáticos usados / Reduction of permanent deformation in pavements designed with hot asphalt mixtures through the incorporation of rubber powder from used tiresContreras Martínez, Cesar Hernán, Mamani Vilcatoma, Diego Paul 20 September 2019 (has links)
El presente trabajo de investigación tiene como objetivo promover el uso del polvo de caucho reciclado como componente en el diseño de mezclas asfálticas con el propósito de disminuir la deformación permanente de la carpeta asfáltica y así mejorar su vida útil mediante el ensayo de la Rueda de Hamburgo.
La problemática del presente trabajo es la falta de información en cuanto a antecedentes del uso del polvo de caucho sobre todo en el medio local. Además en nuestro país no existe una industria dedicada a la elaboración del polvo de caucho. También se debe considerar que en el Perú no existe la cultura de utilizar materiales reciclados como componentes para el mejoramiento del asfalto en proyectos de pavimentos.
La finalidad de esta investigación consiste en dejar un antecedente para seguir con los trabajos de investigación del uso del polvo de caucho y mejorar el diseño de la mezcla asfáltica. Además de promover el uso de materiales reciclados para proyectos de infraestructura vial con el fin de cuidar el medio ambiente y mejorar la calidad de vida de los ciudadanos. / The purpose of this research work is to promote the use of recycled rubber powder as a component in the design of asphalt in order to reduce the permanent deformation of the asphalt binder and thus improve its useful life by using the Hamburg wheel.
The problem of the present work is the lack of information regarding the background of the use of rubber powder especially in the local environment. In addition in our country there is no industry dedicated to the production of rubber powder.It should also be considered that in Peru there is no culture of using recycled materials as components for the improvement of asphalt in pavement projects.
The purpose of this research is to leave a background to continue with the research work on the use of rubber dust and improve the design of the asphalt mix. In addition to promoting the use of recycled materials for road infrastructure projects in order to care for the environment and improve the quality of life of citizens. / Tesis
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Nutzbarmachung des Potentials naturfaserbasierter Werkstoffe als Leichtbau- bzw. KonstruktionsmaterialKuntzsch, Timo, Miletzky, Frank January 2016 (has links)
Aus der Einleitung:
"Ein wachsender Bedarf an nachhaltig verfügbaren Rohstoffen und knapper werdende Rohölressourcen steigern die wirtschaftliche Bedeutung natürlicher Faserstoffe. Das eröffnet neue, über den traditionellen Einsatz von Papier hinausgehende Anwendungen für cellulosische Fasern, beispielsweise in maßgeschneiderten 3D-Verpackungslösungen, im Leichtbau oder in Konstruktionswerkstoffen.
Bei der Erschließung neuer Anwendungsbereiche steht neben der zentralen Kostenfrage das Ziel im Vordergrund, die Bauteile technologisch effizient herzustellen. Dafür sollen weitestgehend etablierte Technologien für die Verarbeitung der eingesetzten Halbzeuge einsetzbar sein, z.T. sind aber auch neue Technologien erforderlich, wie z.B. integriertes Fügen und Umformen. Diese Entwicklungen sind nicht auf die oft als Vorreiter angesehene Automobilbranche beschränkt, sondern betreffen z.B. auch die Möbelbranche, die Baustoffindustrie und zunehmend auch die Papierwirtschaft. ..."
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THE INFLUENCE OF CELLULOSE NANOCRYSTALS ON PERFORMANCE AND TRANSPORT PROPERTIES OF CEMENTITIOUS MATERIALS AND GYPSUMAnthony Paul Becerril (9669782) 16 December 2020 (has links)
<p>Concrete is in everyday life such as parking lots, buildings, bridges, and more. To keep concrete and its constituents together, binders such as cement are used. Cement’s production process is responsible for 8% of global carbon dioxide emissions as of 2018. With global warming being a severe global issue, the challenge of reducing cement carbon dioxide emissions can be greatly beneficial with even slight improvements. Various solutions to this challenge have developed over the years in the form of processing efficiency, material substitution, or material additives. Of the additives for cement and concrete that have been ventured, nanomaterials have had a strong development in recent years. Specifically, cellulose nanomaterials in the form of nanocrystals, nanofibrils, and more have demonstrated great improvement in cement’s performance resulting in a reduction in cement produced and reduction in emissions. This study expands on the knowledge of cellulose nanocrystals as an additive for cement using the formation factor methodology. Formation factor is a resistivity ratio of the specimen and pore solution that can be used in correlation to the diffusion of chloride ions through the use of the Nernst-Einstein equation. This study also investigates the effect that cellulose nanomaterials have on the mechanical properties and thermogravimetric analysis of gypsum, a material commonly used in cement production that delays the hardening of cement. </p>
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Propuesta de mejoramiento de la densidad y resistencia a la compresión no confinada en un suelo cohesivo de alta plasticidad utilizando dos materiales de construcción reciclados en la urbanización Sudamérica ubicada en Talara-Piura / Proposal to improve the density and resistance to unconfined compression in a cohesive soil with high plasticity using two recycled construction materials in the South American urbanization located in Talara-PiuraAbregú Sáenz, Julio Ernesto, Mayon Mallco, Carlos Josimar 09 November 2021 (has links)
Esta investigación tiene como objetivo evaluar el desempeño geotécnico del suelo arcilloso de alta plasticidad de la urbanización Sudamérica en Talara- Piura, mediante la incorporación de dos materiales reciclados polvo cerámico (PCR) y yeso (YSR). En primer lugar, se optó por clasificar el suelo en estados natural el cual se caracterizó por ser una arcilla de alta plasticidad, para luego realizar los ensayos de contenido de humedad, granulometría y límites de consistencia. En segundo lugar, se analizó la muestra con las dos adiciones incorporadas con porcentajes de 2.5%, 5% y 7.5% de YSR y 5%, 10% y 15% de PCR, con el propósito de analizar cuál fue la influencia de las adiciones en la densidad seca y la resistencia a la compresión no confinada del suelo adicionado. Finalmente, los resultados de laboratorio analizados demostraron que la incorporación de los agentes estabilizadores de YSR y PCR aumentan en 7.5% en la densidad máxima seca y 13.5% en el óptimo contenido de humedad respecto a los valores iniciales del suelo en estado natural. Además, la resistencia a la compresión no confinada incrementó, de un valor promedio, de 6.3 kg/cm2 a 28.8 kg/cm2. Estos resultados muestran que al incorporar las adiciones de PCR y YSR son un método valido de implementación frente a fuerzas de compresión, ya que aumentan la capacidad resistente del suelo. / This research aims to evaluate the geotechnical performance of the highly plastic clay soil of the South American urbanization in Talara-Piura, by incorporating two recycled materials: ceramic powder (PCR) and gypsum (YSR). In the first place, it was decided to classify the soil in natural states which was characterized by being a clay of high plasticity, and then carry out tests for moisture content, grain size and consistency limits. Secondly, the sample was analyzed with the two additions incorporated with percentages of 2.5%, 5% and 7.5% of YSR and 5%, 10% and 15% of PCR, in order to analyze what was the influence of the additions in the dry density and unconfined compressive strength of the added soil. Finally, the analyzed laboratory results showed that the incorporation of the stabilizing agents of YSR and PCR increase by 7.5% in the maximum dry density and 13.5% in the optimal moisture content with respect to the initial values of the soil in the natural state. Furthermore, unconfined compressive strength increased, from an average value, from 6.3 kg / cm2 to 28.8 kg / cm2. These results show that incorporating the additions of PCR and YSR are a valid method of implementation against compression forces, since they increase the resistant capacity of the soil. / Tesis
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Novel Acoustic Sensing Method for In-situ Concrete Mechanical Properties MonitoringZhihao Kong (17499687) 30 November 2023 (has links)
<p dir="ltr">In this research, a novel acoustic sensor with a waveguide is made to induce the local volumetric resonance of concrete material. The sensor is embedded in fresh concrete and monitors the in-place elastic modulus and strength development of the concrete. The resonant peak of the EMI spectrum of the sensor is governed by the concrete material in the proximate area of the sensor. The sensor itself does not affect the position of the resonant peak.</p><p dir="ltr">This research covers theoretical demonstration, sensor design and prototyping, remote testing systems, experimental study, and machine learning. Current work demonstrated the sensor successfully produced the resonant peaks that are related to the concrete curing process (R-square=0.86 for lab testing and R-square=0.64 for field testing); however, the sensitivity (S=1.00 Hz/psi) of the resonant frequency is not sufficient for practical application.</p><p dir="ltr">Machine learning algorithms were employed to map the EMI spectra to concrete strength profile. Several existing architectures were explored and evaluated. A novel machine learning scheme was proposed and successfully improved the accuracy of prediction. The algorithm is also able to handle real-time data with decent generalization among diverse concrete mixtures.</p><p dir="ltr">The integration test for the sensing system, including the sensor, the data collection device, the data pipeline, and the trained machine learning models, was performed in field testing of eight States. The averaged MAPE of the field prediction results is 23.43% for field structures and 16.13% for companion beam samples.</p><p dir="ltr">The knowledge produced during this study further advanced the application of EMI sensors in the NDE of concrete material. The EMI resonator tailored for local structural resonance is reported in this study for the first time. The EMI data processing algorithm using machine learning that is generalizable among various concrete mixtures is employed in this study for the first time. This study would be helpful for the real-world application of the EMI technique in the NDE of concrete and other phase-changing materials.</p>
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Análisis de concreto simple con aditivos bituminosos para sobrecimientos ante los efectos del salitre en la ciudad de San JoséVilcahuaman Irigoyen, Vania January 2024 (has links)
Un problema común en las paredes del primer piso es la presencia constante de eflorescencias, que es un desperdicio de sal polvoriento, frecuentemente blanco como la tiza. Esto sucede cuando un ambiente húmedo (suelo sulfatado) disuelve las sales de calcio del concreto y migran a la superficie por capilaridad. Ahora bien, un fenómeno como este podría ser fatal para la construcción, debido a la degradación del material y también para la salud humana. Hoy en día, la gente repara estas apariciones blancas, pero tienden a reaparecer. Por ello, el cemento MS se utiliza para evitar que esto ocurra, pero para ambientes muy agresivos los aditivos son la mejor opción, salvo por su precio. Es por ello que en esta investigación se produjeron y analizaron cilindros de concreto y vigas de mortero de 2 diseños. Estaban compuestos por agregado fino y grueso, cemento MS y emulsión asfáltica (aditivo bituminoso) al 0%, 10%, 20% y 30% del peso del cemento. Ensayos como la resistencia a la compresión, absorción capilar y la exposición acelerada a sulfatos fueron fundamentales para probar la viabilidad de la propuesta, es decir, la cantidad óptima de emulsión. Además, se concluyó que las muestras con 10% y 20% de emulsión asfáltica pueden ser funcionales para fines estructurales (cimentaciones) y no estructurales (recubrimientos), debido a la resistencia a la compresión alcanzada y en comparación con las tradicionales tiene mejor defensa contra los sulfatos. / A common issue on the first-floor walls is the constant presence of efflorescence which is a dusty salt waste, frequently white like chalk. This happens when a humid environment (sulfated soil) dissolves calcium salts of concrete and migrate to the surface by capillarity. Now, a phenomenon like this could be fatal for the construction due to material demotion and also for human health. Nowadays, people repair these white things but they tend to reappear. There for, MS cement is used to prevent this to occur, but for highly aggressive environments additives are the best option, except for its price. That is why in this research, concrete cylinders and mortar beams of 2 designs were produced and analyzed. They were made up of fine and coarse aggregate, MS cement and asphalt emulsion (bituminous additive) of 0%, 10%, 20% and 30% by weight of the cement. Experiments like compressive strength and accelerated exposure to sulfates were fundamental to prove the viability of the proposal, ergo the optimum amount of emulsion. Furthermore, it was concluded that samples with 10% and 20% of asphalt emulsion can be functional for structural (foundations) and non-structural (overlays) purposes because of the reached compressive strength and compared to traditional ones it has better defense against sulfates.
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Mejoramiento de subrasantes arcillosas incorporando agregados de carpetas asfálticas recicladas y cenizas de aserrín en avenida Venezuela, José Leonardo OrtizGonzales Zuñe, Luis Jhosut January 2024 (has links)
Actualmente, el tramo de Av. Venezuela desde Próceres hasta España, presenta un suelo de baja capacidad de soporte, con un grado plástico entre medio a alto y con indicios de ser expansivo, siendo este el responsable de generar problemas de transitabilidad en épocas de lluvias, asentamientos a nivel de vereda y hundimientos en la vía con ausencia de pavimento.
Debido a la problemática anterior, la presente tesis busca mejorar las propiedades físicomecánicas
del suelo mediante la incorporación de agregados de carpetas asfálticas recicladas (CAR) más cenizas de aserrín (CDA), evaluándose las siguientes combinaciones: 50%CAR+4CDA+46%S, 50%CAR+8%CDA+42%S, 60%CAR+4%CDA+36%S, 60%CAR+8%CDA+32%S, 70%CAR+4%CDA+26%S y 70%CAR+8%CDA+22%S, estos
porcentajes fueron ensayados en cada muestra de subrasante arcillosa: ML(C-01), CL(C-02) y CH(C-03).
En base a los ensayos de laboratorio desarrollados, se obtuvo el 70%CAR+4%CDA como porcentajes óptimos de los estabilizantes, ocasionando en las tres subrasantes arcillosas los siguientes cambios: el IP, varió entre 0.55 a 1.00 veces su valor natural, determinándose 17.00%, 18.00% y 17.00% según sea la muestra, así mismo, la MDS, incrementó entre 2.23 a 3.24 veces su valor original, obteniéndose 1.907, 1.930 y 1.922 g/cm3 correspondientemente, en tanto, el CBR(95%), aumentó entre 2.23 a 3.24 veces su valor inicial, alcanzando 9.50%, 6.70% y 9.40% respectivamente, recalcándose que, las tres muestras pasaron de ser una subrasante inadecuada a una regular.
Finalmente, para la ejecución de pavimento flexible cuya subrasante esté mejorada con 70%CAR+4%CDA se necesitará S/893,764.88 soles por cada 500m, no obstante, esta propuesta disminuye al 42.11% los impactos que tradicionalmente se generarán. / Due to the above problems, this thesis seeks to improve the physical-mechanical properties of the soil
by incorporating aggregates of recycled asphalt pavement (RAP) plus sawdust ashes (SDA), evaluating
the following combinations: 50%RAP+4%SDA+46%S, 50%RAP+8%SDA+42%S, 60%RAP+4%SDA+36%S, 60%RAP+8%SDA+32%S, 70%RAP+4%SDA+26%S y 70%RAP+8%SDA+22%S, these percentages were tested in each sample of clayey subgrade: ML(C-01), CL(C-02) and CH(C-03).
Based on the developed laboratory tests, 70%RAP+4%SDA was obtained as optimal percentages of the
stabilizers, causing the following changes in the three clayey subgrades: the IP varied between 0.55 to
1.00 times its natural value, determining 17.00%, 18.00% and 17.00% depending on the sample, likewise, the MDD increased between 2.23 to 3.24 times its original value, obtaining 1.907, 1.930 and 1.922 g/cm3 correspondingly, while the CBR(95%), increased between 2.23 to 3.24 times its initial value, reaching 9.50%, 6.70% and 9.40% respectively, emphasizing that the three samples went from being an inadequate subgrade to a regular one.
Finally, for the execution of flexible pavement whose subgrade is improved with 70%RAP+4%SDA, it
will cost a total of S/893,764.88 per 500m, however, this proposal reduces the impacts that will traditionally be generated to 42.11%.
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Predicción de la resistencia a la compresión del concreto usando redes neuronales artificialesBernilla Rodriguez, David Henry January 2024 (has links)
El concreto es el material de construcción más ampliamente utilizado en la actualidad debido a su excepcional capacidad para resistir fuerzas de compresión, comúnmente denominadas como f'c. La obtención del valor de f'c del concreto involucra la realización de diversos ensayos, siendo el ensayo a compresión simple o uniaxial en probetas de concreto el más comúnmente empleado, evaluando la resistencia a diferentes intervalos de tiempo. Lamentablemente, estas probetas suelen ser desechadas al aire libre, contribuyendo a la contaminación ambiental. En esta investigación, se enfoca en la predicción del valor de f'c del concreto a los 28 días mediante un modelo predictivo basado en redes neuronales artificiales. Los datos de entrada comprenden propiedades de los agregados, tipo de cemento y las proporciones de sus componentes, como agua, cemento y agregados. El único dato de salida es el valor real de f'c obtenido en el ensayo de compresión simple. Estos datos se recopilaron de varios laboratorios en el norte de Perú. La red neuronal se construyó utilizando TensorFlow de Google, con dos capas ocultas que constan de 16 y 8 neuronas respectivamente, y se entrenó durante 450 épocas. Se obtuvo una exactitud en la predicción mayor al 90% en el rango de 210 a 335 kg/cm². / Concrete is currently the most widely used construction material due to its exceptional ability to withstand compressive forces, commonly referred to as CS. Determining the CS value of concrete involves conducting various tests, with the uniaxial or simple compression test on concrete specimens being the most employed, assessing resistance at different time intervals. Unfortunately, these test specimens are often discarded outdoors, contributing to environmental pollution. This research focuses on predicting the CS value of concrete at 28 days using a predictive model based on artificial neural networks. Input data include aggregate properties, cement type, and their component proportions such as water, cement, and aggregates. The only output data is the actual CS value obtained from the simple compression test. This data was collected from multiple laboratories in northern Peru. The neural network was constructed using Google's TensorFlow, with two hidden layers consisting of 16 and 8 neurons, respectively, and trained for 450 epochs. Prediction accuracy exceeded 90% in the range of 210 to 335 kg/ cm².
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