Análisis comparativo del uso de nanosílice y ceniza volante en el concreto hidráulico

Context: Nowadays, nanomaterials constitute an innovative alternative for the construction sector. This study evaluates the benefits of adding nanosilica and fly ash to Portland cement concrete in terms of its mechanical strength properties. Methodology: 45 specimens were used to compare the compressive strength and durability of concrete mixtures with nanosilica and fly ash. The specimens were studied after 7, 14, and 21 days to determine their maximum resistance. Results: The addition of small amounts of nanosilica (up to 1%) significantly improved the compressive strength of the concrete. In contrast, a large amount of fly ash (up to 8%) was required for a noticeable effect. Conclusions: Concrete with nanosilica yielded the best results in terms of mechanical strength. The key to improving concrete through nanosilica and fly ash is to reduce the water-to-cement ratio using chemical agents that reduce porosity and increase resistance.Contexto: Hoy en día, los nanomateriales representan una alternativa innovadora para el sector de la construcción. Este estudio evalúa los beneficios de añadir nanosílice y ceniza volante al concreto de cemento Portland en función de sus propiedades de su resistencia mecánica. Método: Se utilizaron 45 especímenes para comparar la resistencia a la compresión y la durabilidad de mezclas de concreto con nanosílice y ceniza volante. Los especímenes fueron estudiados a los 7, 14 y 21 días para determinar su máxima resistencia. Resultados: La adición de cantidades pequeñas de nanosílice (hasta 1 %) mejoraron significativamente la resistencia a la compresión del concreto. En contrate, se necesitó una gran cantidad de ceniza volante (hasta 8 %) para lograr un efecto notable. Conclusiones: El concreto con nanosílice dio los mejores resultados en cuanto a resistencia mecánica. La clave para mejorar el concreto con nanosílice y ceniza volante es reducir la relación cemento-agua utilizando agentes químicos que reduzcan la porosidad y aumenten la resistencia

Prediction of the Static Modulus of Elasticity Using Four non Destructive Testing

The static modulus of elasticity (Es) is an important parameter in the analysis of hydraulic concrete structures, changes have been made to the regulation of construction; these changes require minimum values for the Es, so now, in addition to concrete compressive strength (f´c) also Es values should be ensured. A methodology to predict Es is proposed, specifically, the Es were modeled by testing: ultrasonic pulse velocity (UPV), electrical resistivity test (ERT), resonance frequency test (RFT), the Hammer Test Rebound (HTR) and f´c. In order to generate models multiple linear regression technique was used. Cylindrical specimens were prepared in two stages, in the first stage was simulated laboratory conditions in the second stage was simulated conditions of concrete made in situ. All cylinders were subjected to non-destructive and destructive tests at different ages. The research objective is to predict Es from the results of destructive tests (traditionally employed to obtain Es) and nondestructive testing. It was possible to obtain a model whose correlation coefficient indicates the good approximation in the generated predictions

Efecto de la adición de grenetina en las propiedades reológicas y de textura de un panqué reducido en margarina

To increase the concentration of gelatin in a formulation for pound cake reduced in margarine and partially replaced by canola oil, there is a proportional increase in specific gravity, apparent viscosity and viscoelastic modules, decreasing the size and number of bubbles formed in the batter. In pound cake, there is a proportional decrease in volume and uniformity of the crumb and increase in the firmness, however, the addition of 1.25% of gelatin was the most accepted sensory formulation due to perceived a crumb more consistent and wet, so, the functionality of the gelatin as hydrocolloid, is limited to the final texture of the pound cake, concluding that it may be an alternative to improve the acceptability of a pound cake reduced in margarine, which is also of lower cost.The use of different hydrocolloids in the partial substitution of margarine by vegetable oils, are evaluated to achieve products with characteristics similar to the traditional product. The objective of this study was to evaluate the effect of the addition of different concentrations of gelatin (0%, 0.75%, 1.25%, and 2.0%) in pound cake formulation reduced in margarine and partially replaced with canola oil. It was determined specific gravity (SG), apparent viscosity, modules of viscoelasticity (G' and G") and number and size of air bubbles in the batter. In the pound cake was determined texture (TPA and sensory evaluation), crumb structure and moisture. By increasing the concentration of gelatin, it was observed a proportional increase of SG, apparent viscosity and elastic and viscous modules, predominating the viscous module with respect to elastic module, and a decrease in the number and size of air bubbles in the batter. In the pound cake, there was a proportional decrease in the volume and uniformity of the crumb, with respect to the size and number of cavities formed, however, sensorially, the most accepted formulation was the addition of 1.25% of gelatin because it perceives a more consistent and moist crumb, therefore, adding gelatin can be an alternative to improve the acceptability of a reduced pancake in margarine, which It's also less expensive.CONACy

Implementación numérica del modelo de elemento finito para cálculo del comportamiento mecánico de las diferentes fases del cemento portland mexicano

El concreto es un material heterogéneo, una mezcla de compuestos que en una magnitud de milésimas de centímetro puede ser diferenciado en tres diferentes fases que contienen mortero, agregados e interfases (Taylor, 1997). A esta escala se pueden llevar a cabo estudios de tipo mesoscópico, útiles para conocer el comportamiento macroscópico de una estructura hecha con concreto (Xiao 2007). Estos análisis son útiles para conocer el comportamiento de determinada mezcla y así saber su comportamiento mecánico o termodinámico. La manera de obtener un modelo que permita dicho estudio se logra a través de la generación de una estructura suficientemente cercana a la real, a través de distribuciones de probabilidad que ubiquen a los componentes, como se muestra en la Figura 1 (Wang et al., 1999). Una vez alcanzada una estructura considerada satisfactoria, se utiliza una malla formada por elementos finitos a través de la cual pueda modelarse un conjunto de características mecánicas o aún termodinámicas sobre este material (Tang et al, 2008).Este reporte cubre las actividades relacionadas con el subproyecto Implementación numérica del modelo de elemento finito para cálculo del comportamiento mecánico de las diferentes fases del cemento portland mexicano, segunda etapa, el cual tiene como objetivo general la programación del modelo de elemento finito para la simulación del comportamiento mecánico de las fases presentes en los productos de hidratación del cemento Portland Mexicano y arenas, es decir modela por medio del elemento finito la interacción mecánica entre al menos dos materiales diferentes

Woody debris trapping phenomena evaluation in bridge piers: A Bayesian perspective

l artículo propone el uso de una red bayesiana y analiza sus ventajas y desventajas para realizar el diagnóstico y la propuesta de remediación en el caso de puentes sujetos a la acumulación de escombros de madera en la base de las pilas.A flood occurs when water and other materials such as woody debris overflow dry areas. If there is infrastructure present, woody fragments could be transported downstream and eventually trapped, leading to increments in the hydrodynamic forces over, say, a bridge. Moreover, local scour can be developed in the structure piers. The purpose of this research is to investigate the bridge pier scour phenomena induced by woody debris from a probabilistic point of view. A Non Parametric Bayesian Belief Network comprising seven nodes has consequently been developed. They are: water level, Froude number, blockage amount, drag force, scour depth, damage and overturning. Through both Monte Carlo Simulation and data from a real structure, the nodes’ non parametric probability distributions have been established, an area that has, to date, received very little attention in the literature. By combining the variables under study, it was possible to determine their interaction and dependencies, showing that the depth of the approaching flow is correlated with two nodes: damage and overturning. The results are useful for bridge managers willing to rank investments in maintenance actions within the industry, and to develop optimal risk based strategies for efficiently employing the scarce resources used to that end

Comportamiento mecánico y caracterización de morteros elaborados con cemento Portland ultrafino

Tesis (Doctorado en Tecnología Avanzada), Instituto Politécnico Nacional, CICATA, Unidad Legaria, 2009, 1 archivo PDF, (68 páginas). tesis.ipn.m

Comparative Analysis of the Use of Nanosilica and Fly Ash in Hydraulic Concrete

Context: Nowadays, nanomaterials constitute an innovative alternative for the construction sector. This study evaluates the benefits of adding nanosilica and fly ash to Portland cement concrete in terms of its mechanical strength properties. Methodology: 45 specimens were used to compare the compressive strength and durability of concrete mixtures with nanosilica and fly ash. The specimens were studied after 7, 14, and 21 days to determine their maximum resistance. Results: The addition of small amounts of nanosilica (up to 1%) significantly improved the compressive strength of the concrete. In contrast, a large amount of fly ash (up to 8%) was required for a noticeable effect. Conclusions: Concrete with nanosilica yielded the best results in terms of mechanical strength. The key to improving concrete through nanosilica and fly ash is to reduce the water-to-cement ratio using chemical agents that reduce porosity and increase resistance

Predicting Concrete Compressive Strength and Modulus of Rupture Using Different NDT Techniques

Quality tests applied to hydraulic concrete such as compressive, tension, and bending strength are used to guarantee proper characteristics of materials. All these assessments are performed by destructive tests (DTs). The trend is to carry out quality analysis using nondestructive tests (NDTs) as has been widely used for decades. This paper proposes a framework for predicting concrete compressive strength and modulus of rupture by combining data from four NDTs: electrical resistivity, ultrasonic pulse velocity, resonant frequency, and hammer test rebound with DTs data. The model, determined from the multiple linear regression technique, produces accurate indicators predictions and categorizes the importance of each NDT estimate. However, the model is identified from all the possible linear combinations of the available NDT, and it was selected using a cross-validation technique. Furthermore, the generality of the model was assessed by comparing results from additional specimens fabricated afterwards

EFFECT OF ADDED GELATIN ON RHEOLOGICAL AND TEXTURAL PROPERTIES OF A POUND CAKE REDUCED IN MARGARINE

To increase the concentration of gelatin in a formulation for pound cake reduced in margarine and partially replaced by canola oil, there is a proportional increase in specific gravity, apparent viscosity and viscoelastic modules, decreasing the size and number of bubbles formed in the batter. In pound cake, there is a proportional decrease in volume and uniformity of the crumb and increase in the firmness, however, the addition of 1.25% of gelatin was the most accepted sensory formulation due to perceived a crumb more consistent and wet, so, the functionality of the gelatin as hydrocolloid, is limited to the final texture of the pound cake, concluding that it may be an alternative to improve the acceptability of a pound cake reduced in margarine, which is also of lower cost.The use of different hydrocolloids in the partial substitution of margarine by vegetable oils, are evaluated to achieve products with characteristics similar to the traditional product. The objective of this study was to evaluate the effect of the addition of different concentrations of gelatin (0%, 0.75%, 1.25%, and 2.0%) in pound cake formulation reduced in margarine and partially replaced with canola oil. It was determined specific gravity (SG), apparent viscosity, modules of viscoelasticity (G' and G") and number and size of air bubbles in the batter. In the pound cake was determined texture (TPA and sensory evaluation), crumb structure and moisture. By increasing the concentration of gelatin, it was observed a proportional increase of SG, apparent viscosity and elastic and viscous modules, predominating the viscous module with respect to elastic module, and a decrease in the number and size of air bubbles in the batter. In the pound cake, there was a proportional decrease in the volume and uniformity of the crumb, with respect to the size and number of cavities formed, however, sensorially, the most accepted formulation was the addition of 1.25% of gelatin because it perceives a more consistent and moist crumb, therefore, adding gelatin can be an alternative to improve the acceptability of a reduced pancake in margarine, which It's also less expensive.CONACy