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Concrete production is characterized by a significant demand for energy and raw materials. The construction, maintenance, and demolition of engineering works cause excessive polluting waste that requires costly disposal. For this reason, alternative reusable materials that improve the mechanical properties of concrete, such as fly ash, are currently being investigated as an effective solution to reduce problems related to environmental impact. This paper analyzed 80 articles indexed in different databases such as ScienceDirect, IOPscience, Scielo, Ebsco, Scopus, SpringerLink, ProQuest, Dialnet, and Semanticscholar, which were not older than seven years since publication, to conduct an updated systematic review of the use, effect, and influence of fly ash on concrete. The methodologies and designs used to obtain the optimum percentages of 5, 10, and 15% were reviewed, analyzing mainly the results obtained when fly ash is used in concrete. Finally, according to the review carried out, it was concluded that fly ashes improve the mechanical and physical characteristics of concrete, and that the optimum dosage is 10% in substitution of ordinary Portland cement applied in simple concrete. [ABSTRACT FROM AUTHOR]

La investigación buscó determinar la incidencia de la ceniza de eucalipto en las propiedades mecánicas del mortero de asentamiento de ladrillos artesanales, por lo cual se utilizó la metodología de enfoque cuantitativo, tipo aplicada, nivel explicativo y diseño cuasiexperimental. La población estuvo constituida por muestras que 36 son en cubos, 36 son rectangulares, 4 muretes y 4 prismas de mortero, a las cuales se les realizo los ensayos en laboratorio tanto a la muestra patrón como a las con adiciones con porcentajes de 1%, 3% y 5% de ceniza de eucalipto. Los resultados con el 1% de adición tuvo notable mejoría, ya que presento superioridad en cuanto a las otras adiciones en todos los ensayos realizados, finalmente se concluyó que la adición de la ceniza de eucalipto influyó de manera positiva en las propiedades mecánicas del mortero.

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Glass fiber-reinforced polymer (GFRP) composite materials are used extensively and increasingly in major industries including aerospace, marine, construction, electrical and automotive. These types of materials have advantages such as low densities, high mechanical properties in certain directions, ease of production and durability. However, its manufacture generates residues and at the end of its life cycle both the fiber and the resin cannot be easily decomposed or recycled. This article explored the influence of recycled GFRPs as reinforcement in limestone calcined clay cements mortar mixes with ratios of 2%,4%,6%, 8% and 10% replacing the fine aggregate weight in the flexural strength, compressive strength, and density. Results demonstrated flexural and compressive strengths in the range of 2.5 MPa-7MPa and 12-28 MPa respectively at the ages of 28 and 56 days. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the physical and mechanical properties of cement-wood composites with the addition of biomass ashes at different levels (0, 5, 10, 15, 20, and 25%). The composites were produced using Portland cement CPII, Eucalyptus grandis particles, and ashes from eucalyptus wood. The tests followed the NBR 7215 (2019) and ASTM E1876 (2022) standards, density, 24-hour thickness swelling, 24-hour water absorption, dynamic modulus of elasticity from non-destructive testing, static modulus of elasticity, and compressive strength at 28 days tests were carried out. After the tests, statistical analysis was performed to verify if there were statistically differences between the means at a 5% level of significance. The partial replacement of cement with ashes shows potential, especially with a 5% replacement, due to better physical and mechanical properties. [ABSTRACT FROM AUTHOR]

Copyright of Revista Novasinergia is the property of REVISTA NOVASINERGIA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ingenius, Revista Ciencia y Tecnología is the property of Universidad Politecnica Salesiana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Contexto: Durante la combustión de carbón se generan grandes cantidades de residuos, como las cenizas de fondo; éstas se han investigado como reemplazo del cemento y como sustituto de la arena para la producción de concreto. Además, este residuo puede ser usado para la fabricación de productos de arcilla. Método: En este estudio, se llevó a cabo una caracterización físico-química y mineralógica de las cenizas de fondo; además, se evaluó la toxicidad del residuo a través del test de lixiviación-Procedimiento de Lixiviación Característico de Toxicidad y del ensayo de ecotoxidad-Daphnia pulex. Seguidamente, se fabricaron ladrillos a nivel de laboratorio con adición de cenizas en 2 %, 4 %, 6 % y 8 % con respecto a la cantidad de arena; se evaluaron propiedades físicas y mecánicas y, se realizaron ensayos ambientales a los ladrillos. Resultados: Los resultados mostraron una reducción de la resistencia a la compresión con el aumento de cenizas; sin embargo, los ladrillos que incorporaron cenizas al 4 % obtuvieron una resistencia de 14,16 MPa el cual cumple con los criterios mínimos de resistencia a la compresión de acuerdo con la norma colombiana para mampostería no estructural. Por otra parte, el ensayo de lixiviación aplicado mostró que las concentraciones de metales lixiviables estaban por debajo de las regulaciones ambientales. Conclusiones: Estos hallazgos demuestran la viabilidad de utilizar hasta un 4 % de cenizas de fondo de carbón como reemplazante de arena en la producción de ladrillos de arcilla. El cual permitirá mitigar los problemas asociados a su eliminación.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents an experimental study on the compressive strength of concrete cylinders reinforced with expanded metal meshes. The investigation aims at comparing the compressive strength of concrete specimens strengthened with expanded metal meshes with different orientations. A series of compression tests were performed to obtain the structural performance on jacketed specimens, and then compare these with the unreinforced concrete cylinders. Expanded metal tubes were fabricated using circular geometries with two cell orientations. The results showed that cell orientation enhance the compressive strength of the specimens. [ABSTRACT FROM AUTHOR]

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The need for biodegradable bone graft biomaterials in orthopedic surgeries is more often each day due to the promotion of natural tissue regeneration. One option is calcium phosphate cements (CPC), that are also osseconductors. However, their low mechanical properties restrict their application to low mechanical requirement areas of the body. The CPC mechanical resistance depends on the entanglement grade of the calcium deficient hydroxyapatite (CDHA), one option to improve it is trough incorporation of nucleating agents (e.g., stoichiometrically hydroxyapatite). This work proposes the use of a biodegradable nucleating agent, as it is Type B carbonated Hydroxyapatite (CHA-B), to improve the CPC performance. It was formulated compositions of alpha tricalcium phosphate (α-TCP) with variations on the amount of CHA-B (0–5–10–15 wt.%). The compression resistance was evaluated and results indicated that 5% CHA-B increases the strength (7.8%) and the elastic modulus (6.16%), while the other additions diminished such values. Besides, the effect on the setting time, the in vitro degradation and in the physicochemical properties was determined through scanning electron microscopy, X-ray diffraction and infrared spectroscopy. Resumen: La necesidad de biomateriales de relleno óseo biodegradables en cirugías ortopédicas es cada vez mayor, ya que promueven la regeneración natural del tejido. Una opción son los cementos de fosfato de calcio (CPC), que además son osteoconductores. Sin embargo, sus bajas propiedades mecánicas limitan su aplicación a zonas del cuerpo de baja exigencia mecánica. La resistencia mecánica de los CPC depende del grado de entrecruzamiento de los cristales formados de hidroxiapatita deficiente en calcio (CDHA), una opción de aumentarla es mediante la incorporación de agentes nucleantes (e.g. hidroxiapatita estequiométrica). Este trabajo propone el uso de un agente nucleante biodegradable, como lo es la Hidroxiapatita carbonatada tipo B (CHA-B), para mejorar el desempeño de los CPC. Se formularon composiciones de fosfato tricálcico alfa (α-TCP) con variaciones en la cantidad de CHA-B (0-5-10-15 wt.%). Se evaluó la resistencia a la compresión determinando que la adicción de 5% de CHA-B aumenta el esfuerzo (7,8%) y el módulo de elasticidad (6,16%), mientras que las demás adicciones disminuyeron dichos valores. Igualmente, se determinó el efecto en el tiempo de fraguado, en la degradación in vitro y en las propiedades fisicoquímicas mediante las técnicas de microscopía electrónica de barrido, difracción de rayos x y espectroscopía infrarroja.

The properties of BaO–CaO–Al2O3–SiO2 (BCAS) glass seal materials reinforced with 5–30 wt.% glass fiber are investigated. The seals are prepared by solid mixing process. The microstructure and phase content of the samples are studied. Mechanical properties are investigated by Vickers micro-hardness, nano-indentation and compression tests. The thermal properties of the samples are evaluated by conducting a dilatometry analysis. The electrical conductivity and leak resistance of the seal materials are measured at high temperatures. Increasing the amount of glass fiber in the composite samples decreases the magnitude of the thermal expansion coefficient. It is found the addition of just 5 wt.% of glass fiber (GF5sample) increases the indentation fracture toughness of the seals by ∼280% without impairing other properties. It is also found that the GF5 sample has high electrical resistivity with the activation energy of 63.7 kJ/mol and very low leak rate of 1.7 × 10−4 sccm/cm at 750 °C. Resumen: Se investigan las propiedades del sello de vidrio BaO-CaO-Al2O3-SiO2 (BCAS) con el 5-30% en peso de fibra de vidrio. Los sellos se preparan mediante un proceso de mezcla sólida. Se estudia la microestructura y el contenido de fase de las muestras. Las propiedades mecánicas se investigan mediante ensayos de microdureza, nano indentación y compresión de Vickers. Las propiedades térmicas de las muestras se evalúan realizando el análisis de dilatometría. La conductividad eléctrica y la resistencia a fugas de los materiales del sello se miden a altas temperaturas. El aumento de la cantidad de fibra de vidrio en las muestras compuestas disminuye la magnitud del coeficiente de expansión térmica. Se encuentra que con la adición de solo el 5% en peso de fibra de vidrio (muestra GF5) aumenta la resistencia a la fractura por indentación de los sellos en ∼280%, sin afectar otras propiedades. También se encuentra que la muestra GF5 tiene alta resistividad eléctrica con energía de activación de 63.7 kJ/mol y una tasa de fuga muy baja de 1.7 × 10−4 sccm/cm a 750 °C.

Copyright of Ingeniería (0121-750X) is the property of Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Concrete is one of the most used materials in the building sector. Inevitably, concrete gains strength and develops shrinkage cracks during the curing process. Shrinkage cracks provide an entry point for reactive fluids to get into the concrete core. Under favorable conditions, the fluids reduce the pH of the core and consequentially corrode the reinforcing bars. This research shows the use of Bacillus megaterium MTCC 3353, which produces calcium carbonate and closes the minute fissures. Part substitution of cement with metakaolin was also done in the study. It was seen that the bio-based concrete specimens enhanced the mechanical strength and durability parameters. The calcite precipitation was validated using a microstructure study. FESEM and XRD tests show the presence of calcite (calcium carbonate) inside the concrete structure. The bacteria were tested for their growth when superplasticizers were added to them. The bacteria showed normal growth compared to the conventional testing. [ABSTRACT FROM AUTHOR]

Some of the most important industries, such as aerospace, automotive, among others, have stipulated new requirements for materials behavior that include high specific, mechanical, and thermal properties. According to this, nanocomposites have emerged to satisfy these requirements. However, manufacturing these nanocomposites implies cost and time-consuming problems that do not allow their use in technological applications; additionally, the lack of knowledge about the prediction of their mechanical properties is an obstacle to its technological implementation. Therefore, several studies have focused on the development of computational models to predict the mechanical behavior of nano-reinforced composites. In the present work, a comparative assessment of the main computational models for predicting the tensile strength of nanocomposites is carried out. Firstly, a new taxonomy of these models is proposed, which allows identifying the main experimental variables, model evolution, and precision. With the categorization, computational algorithms are developed for these models for predicting the tensile strength of nanocomposites, accomplishing a comparative analysis of accuracy, robustness, and time-cost among them. The precision of these models is evaluated by deeming benchmark experimental works focused on the tensile strength of nanocomposites. The results obtained demonstrated a minimum relative error of 44.7%, 10.1%, and 10.6% for First-Generation, Second-Generation, and Third-Generation models, respectively. [ABSTRACT FROM AUTHOR]

Pervious pavements emerge as an alternative for good management of surface runoff, providing the opportunity to quickly and efficiently reduce the potential for flooding and reuse rainwater. However, the mechanical and hydraulic performance of the material have been extensively evaluated at the laboratory level, leaving aside how the material will behave in the field and how its exposure will accelerate the loss of its hydraulic properties (clogging). In this sense, this research evaluated the mechanical and hydraulic performance of permeable concrete pavements in an experimental field that simulates the working conditions of the material, where properties such as compressive strength, tensile strength, porosity, and permeability were evaluated, as well as the loss of hydraulic efficiency due to clogging. This is to increase the knowledge of the material to provide construction and quality control guidelines that guarantee the correct functioning of this type of pavement, considering its great contribution to sustainability. [ABSTRACT FROM AUTHOR]

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Copyright of Momento: Revista de Física is the property of Universidad Nacional de Colombia, Departamento de Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this paper is to carry out a literature review on the effects of using wood ash as a component in concrete, in order to determine its mechanical properties and behavior. A review of 80 refereed and indexed articles was carried out. The key words were: "concrete and wood ash, replacement of cement with wood ashes, percentages of wood ash in concrete. From this review it is concluded that the use of wood ash provides better physical-mechanical behavior when used in materials such as concrete; however, its adequate percentages range from 5 to 15%, given that in these proportions it has allowed obtaining an increase in relation to the standard concrete of 76% of its compressive strength. [ABSTRACT FROM AUTHOR]

Copyright of ESPOCH Congresses: The Ecuadorian Journal of S.T.E.A.M. is the property of Knowledge E DMCC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of ESPOCH Congresses: The Ecuadorian Journal of S.T.E.A.M. is the property of Knowledge E DMCC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The focus of this paper is to investigate the behavior of the fresh and hardened state of alkali-activated cementitious pastes obtained from the mixture of bottom ash/BOF slag and fly ash/BOF slag. For this purpose, the properties in the fresh and hardened state were evaluated. Ten pastes were produced in two separate systems, whose proportions between ashes and BOF slag were 100:0, 75:25, 50:50, 25:75, and 0:100 (fly ash or bottom ash: BOF slag). In general, the addition of BOF steel slag works by accelerating the setting times, at room temperature curing. In addition, the stress-strain curves demonstrated that heavy ash and BOF steel slag favor the ductile behavior under axial stress. Furthermore, the addition of BOF slag can influence the properties in the fresh and hardened state. Therefore, it is feasible to use steel slag combined with coal ash in alkaline activated binary mixtures. [ABSTRACT FROM AUTHOR]

Biobased particleboards from rice husk (RH) and soybean protein concentrate (SPC) based adhesive were evaluated over 180 days under indoor conditions. Two alternatives were evaluated: the incorporation of carvacrol to the SPC based adhesive, as a natural preservative, and the coating of the RH-SPC based particleboards with a polyurethane lacquer. Coated panels showed the lowest thickness swelling and water absorption at 2 and 24 h of immersion. The modulus of rupture (MOR) increased for the coated panels, while the elasticity modulus (MOE) was the same for all formulations. MOR and MOE obtained for all particleboards evaluated over time met the requirements established by ANSI Standard A208.1 along the 180 days of study. Results showed that particleboard have good physical and mechanical stability under indoor environmental conditions, presenting a good performance at least up to six months. [ABSTRACT FROM AUTHOR]

This research evaluates the changes brought about by the addition of asphalt emulsion and steel filings in clayey soils for subgrade in urban pavements. For this study, different dosages of each additive were established, being 1%, 2%, 4%, 8%, and 15% for the steel filings and 3%, 6%, 9%, 13%, and 18% for the asphalt emulsion, obtaining favorable results in the subgrade in accordance with the CE.010 Urban Pavement standard. With the steel filings the CBR (California Bearing Ratio) had a linear increase whose maximum value was reached with the dosage of 15% increasing the CBR considerably by 189.47% above the CBR of the natural soil; on the other hand, with the asphalt emulsion a maximum increase in CBR was obtained with the dosage of 13% obtaining an increase of 236.84% and after that a decrease is observed with the addition of 18% of asphalt emulsion. [ABSTRACT FROM AUTHOR]

Nature has served as inspiration for multiple areas of knowledge and development of humanity, in the case of materials, their evolutionary process of millions of years has managed to obtain a good compatibility between the mechanical properties of rigidity and toughness, something that is complicated in conventional engineering materials, because these properties behave inversely proportional to each other. It has been established that the formation of hierarchical structures is one of the features that nature uses, ranging from the micrometric scale to the macro scale, with this type of organization, nature has improved various properties, depending on the need to be resolved, the environment in which it is located and the available materials. Helicoidal structures are one of these types of structures and they are present in fish scales, mollusk shells, exoskeletons, etc., these structures provide protection and good mechanical properties and resistance to penetration, impact and fracture. For this reason, it is intended to carry out a numerical study of materials composed of continuous fibers using different constitutive models (lineal and bilinear plasticity) for the matrix (soft) and fibers (stiff) and observe how the variation of the pattern used and the angle of rotation of the fibers affect the overall stiffness and toughness of the material. [ABSTRACT FROM AUTHOR]

In recent years, research on composite materials has increased interest in new materials and the development of engineering applications. This research is focused on characterizing natural fiber-reinforced epoxy resin composites using cabuya fiber compared to the sugarcane fiber reinforcement through experimental tests based on ASTM standards for composite materials and a nonlinear and explicit transient dynamic finite element method FEM. The results determined that material M01 (cabuya fiber and epoxy resin) and configuration C02 (matrix 60% - reinforcement 40%) improved mechanical properties according to the experimental and FEM results; the statistical analysis concluded that the best mechanical properties are focused on the type of material, not in the configurations. The behavior of the fibers and adhesions between the matrix and reinforcing materials were analyzed by a fractographic method of the samples after testing. The comparative tests determined that the FEM analysis has an error of less than 1% in the maximum tensile strength and less than 10% for the maximum strength and force applied in bending, validating, and guaranteeing its use in CAE applications with a mathematical model according to the methodological criteria supported by the state of the art. [ABSTRACT FROM AUTHOR]

This document contemplates a critical reflection of the technological advances in biological and chemical tests that concrete is subjected to through the incorporation of bacteria, with the aim of knowing the different microbial elements that have biomineralization properties capable of self-healing in concrete. Likewise, the methods and applications of bacteria in concrete were reviewed in order to improve its mechanical properties to the different demands placed on modern structures, and at the same time contribute to the reduction of gases that are harmful to the environment. In the development of this manuscript, 80 articles indexed between the years 2017 to 2021 were reviewed, distributed as follows, 51 in Scopus, 17 in Ebsco, and 12 in SciencieDirect, pointing out and describing that microbial concrete has a promising approach in the future. Near. The results achieved with the incorporation of the different Bacillus bacteria, such as Bacillus subtillis, B, cohnii, B. pasteurii, B. pseudofirmus, B. megaterium among others, in different concentrations of cells / ml., Showed great effectiveness in the crack healing, also increasing resistance to compression, bending and traction in concrete. Based on the literary review, it is concluded that the microbial precipitation of calcium carbonate by ureolysis in the concrete matrix mitigates cracking, improves strength, increases durability and, therefore, reduces costs in repairing structures. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ingeniería (0121-750X) is the property of Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

La naturaleza ha servido de inspiración para múltiples áreas del conocimiento y de desarrollo de la humanidad, en el caso de los materiales su proceso evolutivo de millones de años ha logrado obtener una buena compatibilidad entre las propiedades mecánicas de rigidez y tenacidad, algo que es complicado en los materiales de ingeniería convencionales, debido a que estas propiedades presentan un comportamiento inversamente proporcional entre sí. Se ha establecido que una de las características que la naturaleza utiliza es la formación de estructuras jerárquicas, que pueden ir desde la escala micrométrica hasta la macro escala, con este tipo de organización ha logrado mejorar diversas propiedades, dependiendo de la necesidad a resolver, del medio ambiente en que se encuentre y los materiales disponibles. Uno de estos tipos de estructuras son las helicoidales, presentes en escamas de peces, conchas de moluscos, exoesqueletos, etc., la cual provee protección y buenas propiedades de resistencia mecánica, resistencia a la penetración, al impacto y la fractura. Por tal motivo se pretende realizar un estudio numérico de materiales compuestos por fibras continúas empleando diferentes modelos constitutivos (lineales y plásticos bilineales) para la matriz (suave) y las fibras (rígidas) y observar como la variación del modelo empleado y el ángulo de rotación de las fibras afectan la rigidez general y la tenacidad del material.

La presente investigación tiene como objetivo evaluar el efecto de variables experimentales en el estudio de la degradación por cloruros de concretos reforzados con fibras de acero (SFRCs). La información fue recopilada de diferentes fuentes literarias para después ser tratada mediante el diseño experimental de Taguchi y análisis de regresión. Los resultados muestran que los factores más influyentes en la degradación de SFRCs degradados por cloruro son la carga durante la degradación y el ancho de fisura, factores que impactan estadísticamente sobre resistencia residual y la carga máxima a flexión. Sin embargo, otros como la relación agua/cemento, el volumen de fibras, la concentración de cloruros y el tiempo de degradación demostraron poca influencia sobre la respuesta mecánica de los SFRCs.

La necesidad de responder a los problemas ambientales causados por los rechazos mineros, muchos enfoques llevados a cabo para resolver estos problemas. En este trabajo, se estudió el relave de mineral de oro proporcionado por la mina Amesmessa como sustitución en el mortero de cemento. Las cantidades de sustitución estudiadas fueron 0, 10, 20, 30 y 40 % del cemento en peso. Se relevó la composición mineralógica de las principales fases de la hidratación del cemento. Se realizaron pruebas experimentales como la compresión, la porosidad y la absorción de agua. Las pruebas revelaron que la sustitución del cemento al 10% es la cantidad óptima para sustituir el cemento. Se demostró una resistencia a la compresión de 33 Mpa, una porosidad de 10,31% y una absorción de agua de 4,83%. Estos valores se acercan a los de las muestras de referencia. Esta sustitución permite preservar el medio ambiente desde dos puntos de vista, mediante la valorización de los residuos de mineral de oro y la disminución de la emisión de CO2 con la disminución de la producción de cemento. Abstract The need to respond the environmental problems causing by mining rejects, many approaches carried out to resolve these problems. In this work, we studied the gold ore tailing provided by Amesmessa mine as replacement in cement mortar. The substitution amounts studied 0, 10, 20, 30, and 40 % of cement in weight. The mineralogical composition was relieved the principal phases of the cement hydration. Experimental tests carried out such as compressive, porosity, water absorption. The tests revealed that the replacement of cement at 10% percent is the optimum amount to replace cement. It showed 33 Mpa of compressive strength, 10.31% porosity, 4.83% water absorption. These values are so close to those of reference samples. This substitution allows preserving the environment from two sides, by valorizing the gold ore tailing and diminishing the CO2 emission with diminishing the cement production.

Contexto: La preocupación por la mitigación del impacto ambiental generado por el uso de fibras sintéticas como refuerzo de los materiales compuestos tradicionales ha promovido el diseño y caracterización de compuestos elaborados a partir de la combinación de materiales de origen vegetal. No obstante, a pesar de sus múltiples ventajas, para su empleo eficiente como materiales de construcción es necesario profundizar en la determinación del efecto de los parámetros de diseño en su desempeño mecánico. Método: El presente estudio tiene como objetivo determinar el efecto de los parámetros de diseño (tipo de fibras y tratamiento superficial en las propiedades físicas y mecánicas de paneles elaborados con materiales (fibras y resina) de origen vegetal. Para la elaboración del compuesto fueron utilizadas dos tipos de fibras: fibras de Arundo Dónax y fibras de Guadua Angustifolia Kunth. Para la elaboración de los paneles las fibras fueron distribuidas de manera aleatoria en una resina vegetal, obtenida a partir del procesamiento del aceite de ricino. Para evaluar el efecto del tratamiento en las propiedades del compuesto tres condiciones fueron consideradas: fibras sin tratamiento, fibras tratadas con solución de hidróxido de sodio y fibras tratadas con plasma. La densidad en estado anhidro, la capacidad de absorción efectiva, la absorción superficial, el porcentaje de hinchamiento, el módulo de rotura y el módulo de elasticidad aparente fueron determinados experimentalmente. A partir de los resultados experimentales se realizó un análisis de la superficie de respuesta mediante la implementación de un diseño central compuesto, utilizando un programa comercial. Resultados: A partir de los resultados experimentales se realizó un análisis de la superficie de respuesta. Para cada una de las propiedades estudiadas se obtuvieron los diagramas de Pareto y los gráficos de contorno. A partir de los resultados estadísticos fue posible establecer ecuaciones que permiten predecir las propiedades del compuesto en función del tipo de fibra y el tratamiento aplicado en su superficie. Conclusiones: A partir de los resultados obtenidos fue posible verificar el efecto del tipo de fibras y de su modificación superficial en las propiedades físicas de compuestos elaborados con materiales de origen vegetal. Otros parámetros como orientación de las fibras, así como variables asociadas a las condiciones de procesamiento (presión y tiempo de compactación) pueden influir en las propiedades del material) y serán abordadas en trabajos futuros.

Los envases biodegradables a base de almidón son una alternativa para disminuir la fracción de residuos sólidos urbanos originados por el uso de bandejas de poliestireno expandido, generalmente difíciles de biodegradarse. En el presente trabajo se ha investigado la obtención de una bandeja biodegradable de almidón de papa (A), fibra de tocones de espárrago (F) y glicerina (G), en un proceso de termoformado con presión de 24 bar a 150 °C por un tiempo de 20 minutos. Se empleó el Diseño de Mezclas Simplex Centroide para determinar las cantidades de los componentes en cada tratamiento. Las bandejas fueron caracterizadas mediante pruebas físicas (espesor y densidad) y pruebas mecánicas (fracturabilidad, dureza, resistencia a la tracción y porcentaje de elongación). Finalmente, mediante el uso de la función deseabilidad, se determinó que la mezcla óptima para la obtención de bandejas biodegradables fue la relación F/A de 85/6,89 y % G de 13,11%, que maximizó los valores de dureza (19,19 kg), fracturabilidad (9,09 mm), resistencia a la tracción (0,133 MPa) y porcentaje de elongación (2,998 mm).

La implementación de materiales con mayores resistencias en el medio constructivo ofrece importantes ventajas a nivel estructural y económico en obras civiles de gran magnitud. Este artículo pretende estudiar la influencia del concreto (f’c 55 MPa) y refuerzo de alta resistencia (Grado 80), frente al hormigón f’c 28 MPa y varillas Grado 60, en edificios de mediana altura con sistema dual. Ambas propuestas de diseño se localizan en el centro norte de Quito. Estas son comprendidas por 18 pisos en elevación y 4 subsuelos, destinados a departamentos habitacionales y locales comerciales. La Norma Ecuatoriana de la Construcción sustentada en el ACI, establece las bases fundamentales y parámetros para su diseño, partiendo de su predimensionamiento, seguido de la modelación, análisis estructural y finalizando con su diseño hasta la definición de planos estructurales. Haciendo uso de software de modelación estructural, se aplican tres importantes análisis a estas edificaciones: lineal estático, dinámico y pushover; verificando así, su comportamiento frente a las cargas verticales y laterales a las que se ven sometidas y la resistencia de sus diferentes elementos. Una vez detallados los planos estructurales, se procede a la cuantificación del volumen del concreto y peso de las varillas de refuerzo con su debido análisis de precios unitarios para establecer los presupuestos de cada propuesta. Finalmente, todos los resultados son recopilados y analizados, tanto a nivel estructural como económico, con el fin de evaluar la influencia de los materiales de alta resistencia respecto a los convencionales, definiendo los pros y contras de ambas propuestas de diseño.

El presente documento contempla una reflexión crítica de los avances tecnológicos en ensayos biológicos y químicos que es sometido el concreto mediante la incorporación de bacterias, con el objetivo de conocer los distintos elementos microbianos que poseen propiedades de biomineralización capaces de realizar la autocuración en el concreto, asimismo, se revisaron métodos y aplicaciones de las bacterias en el concreto con el fin de mejorar sus propiedades mecánicas a las diferentes exigencias sometidas las estructuras modernas, y al mismo tiempo contribuir con la reducción de gases dañinos al medio ambiente. En el desarrollo de este manuscrito se revisaron 80 artículos indexados entre los años 2017 al 2021 distribuidos de la siguiente manera, 51 en Scopus, 17 en Ebsco, y 12 en SciencieDirect, señalando y describiendo que el concreto microbiano tiene un enfoque prometedor en un futuro cercano. Los resultados alcanzados con la incorporación de las diferentes bacterias de Bacillus, como son Bacillus subtillis, B, cohnii, B. pasteurii, B. pseudofirmus, B. megaterium entre otros, en diferentes concentraciones de células/ml., mostraron gran efectividad en la cicatrización de grietas, aumentando también la resistencia a la compresión, flexión y tracción en el concreto. Sobre la base de la revisión literaria se concluye que la precipitación microbiana de carbonato de calcio mediante ureólisis en la matriz del concreto, mitiga el agrietamiento, mejora la resistencia, aumenta la durabilidad y, por lo tanto, disminuye los costes en reparación de las estructuras.

Mortar is considered one of the construction materials in great demand in the world, obtaining materials for its preparation require the exploitation of a large part of renewable and nonrenewable resources. In order to dissipate the consumption of natural aggregates, the reuse of different materials that are normally discarded has been studied; glass is an important option for the preparation of mortar. Therefore, the objective of the present investigation was to design a mortar for masonry incorporating crushed glass. The mixing design was made for dosages of 1: 3.5, 1: 4, 1: 5 and 1: 6 with substitution of 5%, 10%, 15%, 20%, 25% and 30% of fine aggregate by crushed glass; tested at the age of 7, 14, 21 and 28 days. The fluidity of the mortar in fresh state and the mechanical properties such as the resistance to compression and bending of the mortar, resistance to adhesion by bending in masonry piles, resistance to axial compression of piles and resistance to diagonal compression in walls were evaluated. of bricklayer. The highest resistance was obtained for the dosage of 1: 3.5 with 30% as the optimum percentage of substitution, reaching a higher resistance compared to the standard mortar; for the dosage of 1: 4 the optimum percentage was 25%; for 1: 5 it was determined with 20%; and finally, 10% was obtained as the best percentage for the 1: 6 dosages. From these values it was determined that, once the optimal percentages were reached, the strength of the mortar decreases as the substitution increases. The results obtained allowed to conclude that the crushed glass significantly influences the mortar properties. [ABSTRACT FROM AUTHOR]

To study the influence of the curing procedure polymer-modified cement mortars (PMCM) were realized in two stages. In stage 1, PMCM with different percentages of PVA (5, 10, and 15%) were produced considering two times of PVA addition in the mix (3 and 6 minutes) evaluating the fresh and the hardened state. Stage 2, focuses on analyses of different cure procedures: dry, wet, and two types of intermittent cure (dry/wet and wet/dry) by compressive, tensile strength, water absorption, and dynamic modulus of elasticity. In stage 1, the mixtures produced with 10 and 15% of PVA were selected for their results. Regarding the time of addition of the PVA to the mix, the results obtained do not show significant differences when the samples were produced with the two times. Then the addition time of 3 minutes is considered optimal, for manufacturing efficiency. In stage 2, the results show that the cure influences the performance of the PMCM, wherein the M1 cure showed the best results in the mechanical properties (justified by the correct hydration of the cement). In general, the incorporation of polymer reduced the absorption of water and the dynamic modulus of elasticity, thus contributing to producing more durable materials. [ABSTRACT FROM AUTHOR]

This work shows the experimental results obtained from the manufacture and characterization of cellular metals with open or interconnected pore. As a base metal we use an aluminumsilicon alloy for casting and for manufacturing we use the modified removable filler infiltration technique. As a filler material, high purity sea salt with three particle size ranges was used. The samples obtained were characterized in terms of their morphology and pore topology using Scanning Electron Microscopy. Using simple mathematical models, structural characteristics such as density, relative density and percentage of porosity were determined. Based on quasi-static compression tests, stress-strain curves were constructed and mechanical properties such as stiffness, plateau stress, densification deformation and mechanical energy absorption capacity of these materials were obtained. The results show that increasing the pore size increases density, relative density and decreases porosity and energy absorption capacity. [ABSTRACT FROM AUTHOR]

Currently seeking to improve the characteristics of concrete, the use of drawn steel fibers in a self-compacting concrete can increase resistance and reduce cracks, with a high level of fluidity for installation. The objective of this research is to evaluate the properties of selfcompacting concrete by adding drawn steel fibers. Concrete samples were made by adding 1%, 1.5%, 2%, 2.5% fiber CHO 80/60 and 65/35 NB, with concrete specimens to be tested at 7, 14 and 28 days of curing, to Analyze the physical and mechanical properties. The results showed that they increased the compressive strength by 4.94%, traction by 8.15% and bending by 6.64% with the addition of 1.5% of the two fibers. It is concluded that adding drawn steel fiber contributes to the mechanical properties and can be a great alternative for high-strength concrete. [ABSTRACT FROM AUTHOR]

El creciente aumento de residuos derivados de actividades como la demolición y su potencial reciclaje, permiten realizar un análisis comparativo de estudios experimentales y tres artículos en donde se ha incorporado residuos de yeso calcinado para la elaboración de probetas y placas entre 5% al 100% de incorporación de residuo y con granulometrías que varían del 0.063mm hasta 4mm, las muestras se han curado en condiciones de temperatura ambiente y cámara húmeda para determinar la influencia que pueden ejercer las condiciones de curado en sus características físicas y mecánicas. Los resultados resaltantes muestran la disminución gradual de la densidad de mayor granulometría a la menor, así mismo influye de forma inversa el porcentaje de adicción, con respecto a la resistencia a flexión a menor granulometría menor disminución de la resistencia a flexión, donde los mejores resultados obtenidos corresponden al compuesto de árido fino con un porcentaje de adicción al 100%. Abstract The increase of construction waste derived from activities such as demolition and its recycling potential, allow a comparative analysis of different specimens and three articles in which calcined gypsum waste has been incorporated for the preparation of test tubes and plasterboard between 5% to 100% of aggregate and with sizes between 0.063mm to 4mm, the samples have been cured in conditions of room temperature and a humid chamber to determine the influence that curing conditions on their physical and mechanical characteristics. The outstanding results show the gradual decrease of the density from the highest to the smallest size, likewise the percentage of addition influences in an inverse way, with respect to the flexural strength, the lower the size of aggregate, the lower the decrease in the flexural strength, where the best result was obtained from fine aggregate with a 100% addiction percentage.

En la investigación se propuso desarrollar un concreto autocompactante mediante la metodología del ACI 237R-07 re-aprobada el 2019, con materiales encontrados en el medio y aditivo reductor de agua de alto rango de base policarboxilato Eucoplast 8500HP adicionando Fibras Sintéticas SikaCem®-1 Fiber, buscando mejorar las propiedades mecánicas del concreto autocompactante. La investigación presenta un enfoque cuantitativo, de nivel descriptivo, haciendo uso del método hipotético-deductivo y se presenta un diseño cuasi-experimental pudiendo así verificar las hipótesis planteadas. Se realizó un muestreo no probabilístico por conveniencia donde la muestra es igual a la población, siendo un total de 90 especímenes. Se cumplieron las características de capacidad de paso, capacidad de relleno y resistencia a la segregación propios de este tipo de concreto, cumpliéndose las Directrices para el Hormigón Autocompactante 2006 y del ACI 237R-07. De acuerdo a la evaluación de las propiedades mecánicas del concreto autocompactante, la adición de las Fibras Sintéticas SikaCem®-1 Fiber mejoran levemente las propiedades mecánicas hasta en un 4.54% el peso unitario, en un 11.39% la resistencia a la compresión, un 12.47% el módulo de rotura y hasta en un 12.08% el módulo de elasticidad. Concluyendo que el uso de la Fibra Sintética en el Concreto Autocompactante es favorable.

Bone china samples were produced using two different milling methods: low-energy ball milling (LEBM) for 3 and 24 h, and high-energy ball milling (HEBM) for 5 min. After pressing, the samples were sintered at temperatures ranging from 1100 °C to 1250 °C. HEBM 5 min yields a raw materials’ specific surface area (BET) almost 50% higher than LEBM 24 h. The highest density was obtained for samples prepared by HEBM 5 min (2.65 g/cm3), sintered at 1200 °C, which is 4.4% higher than that obtained for the sample made by LEBM 24 h. Samples prepared by HEBM 5 min and LEBM 24 h exhibit similar Vickers hardness, indentation fracture toughness and, wear coefficient. Overall, these samples exhibit better mechanical properties than those of the samples prepared by LEBM 3 h. The milling method influences the translucency of bone china up to a firing temperature of about 1150 °C. Above this temperature, the formation of the liquid phase reduces porosity and, consequently, light scattering, regardless of the milling method used to produce bone china. Even so, HEBM still has a beneficial role in making bone china more homogeneous as compared to those produced by LEBM. Resumen: Las muestras de porcelana de huesos se produjeron utilizando 2 métodos de molienda: baja energía (LEBM) durante 3 y 24 h y alta energía (HEBM) durante 5 min. Después del prensado, las muestras se quemaron entre 1.100 y 1.250 °C. La HEBM 5 min produce una superficie específica de materias primas casi un 50% más alta que la LEBM 24 h. La mayor densidad se obtuvo para muestras preparadas por la HEBM 5 min (2,65 g/cm3) y quemadas a 1.200 °C, el 4,4% más que la obtenida por la LEBM 24 h. Las muestras HEBM 5 min y LEBM 24 h mostraron dureza Vickers, tenacidad a la fractura por indentación y coeficiente de desgaste similares. En general, ambas muestras exhiben mejores propiedades mecánicas que las muestras preparadas por la LEBM 3 h. El método de molienda influye en la translucidez de la porcelana de hueso a una temperatura de cocción de alrededor de 1.150 °C. Por encima de esta temperatura, la formación de la fase líquida reduce la porosidad y la dispersión de la luz, independientemente del método de molienda utilizado para producir porcelana para huesos. Aun así, la HEBM hace que la porcelana de huesos sea más homogénea en comparación con las producidas por la LEBM.

La elaboración de materiales biodegradables surge como alternativa para disminuir la contaminación causada por los desechos plásticos al medio ambiente, con esta premisa, se propuso este estudio comprendido en el desarrollo de biopolímeros plásticos, a partir de compuestos bioactivos con diferentes matrices de almidón modificado de yuca (5 – 12 %), colágeno de escamas de pescado (10 – 40 %), aceite esencial de limón (0,5 - 1,5 %) y temperatura de gelatinización (70 – 80 °C). Se utilizó un diseño experimental de superficie de respuesta Box Behnken; con la determinación de sus propiedades mecánicas (esfuerzo máximo, módulo de Young, fuerza de corte, esfuerzo a la ruptura y porcentaje de elongación de ruptura). Según los resultados encontrados, se determinó que el almidón modificado de yuca fue el de mayor influencia en las propiedades mecánicas, teniendo en cuenta su importancia para crear materiales más resistentes, pero evidencia dificultades plastificantes, donde el colágeno de escamas de pescado incide significativamente. Además, se evidencia que el aceite esencial de limón presentó gran influencia en el módulo de Young (46,28 ± 2,31 MPa), y en el porcentaje de elongación (69,69 ± 2,16 %); mientras que la temperatura de gelatinización de 80 °C no es recomendada para este tipo de matrices almidón - proteína por daños de la estructura; determinando una mejor resistencia mecánica y un gran aumento del módulo de Young. En conclusión, las características y el rendimiento de la película a base de almidón de yuca, colágeno de escamas, y aceite esencial de limón; tienen un impacto al considerar el nivel máximo de eficacia mecánica de películas biodegradables y alcanzar un mejor comportamiento en sus propiedades mecánicas.

La elaboración de materiales biodegradables surge como alternativa para disminuir la contaminación causada por los desechos plásticos al medio ambiente, con esta premisa, se propuso este estudio comprendido en el desarrollo de biopolímeros plásticos, a partir de compuestos bioactivos con diferentes matrices de almidón modificado de yuca (5 – 12 %), colágeno de escamas de pescado (10 – 40 %), aceite esencial de limón (0,5 - 1,5 %) y temperatura de gelatinización (70 – 80 °C). Se utilizó un diseño experimental de superficie de respuesta Box Behnken; con la determinación de sus propiedades mecánicas (esfuerzo máximo, módulo de Young, fuerza de corte, esfuerzo a la ruptura y porcentaje de elongación de ruptura). Según los resultados encontrados, se determinó que el almidón modificado de yuca fue el de mayor influencia en las propiedades mecánicas, teniendo en cuenta su importancia para crear materiales más resistentes, pero evidencia dificultades plastificantes, donde el colágeno de escamas de pescado incide significativamente. Además, se evidencia que el aceite esencial de limón presentó gran influencia en el módulo de Young (46,28 ± 2,31 MPa), y en el porcentaje de elongación (69,69 ± 2,16 %); mientras que la temperatura de gelatinización de 80 °C no es recomendada para este tipo de matrices almidón - proteína por daños de la estructura; determinando una mejor resistencia mecánica y un gran aumento del módulo de Young. En conclusión, las características y el rendimiento de la película a base de almidón de yuca, colágeno de escamas, y aceite esencial de limón; tienen un impacto al considerar el nivel máximo de eficacia mecánica de películas biodegradables y alcanzar un mejor comportamiento en sus propiedades mecánicas.

Lightweight concrete (LWC) has become an outstanding material in the construction sector to conform nonstructural and structural members into buildings. Expanded clay aggregate is a special type of lightweight aggregate formed by heating clay with little lime content, having low unit weight, high durability, and mechanical strength. Despite the massive use of the expanded clay lightweight aggregate worldwide, their use in the Colombian context is still limited. This research reports the characterization of the behavior of lightweight concrete from Colombian expanded clay aggregates. Experimental tests on fresh and hardened state (compressive strength, apparent density, and chloride migration) were carried out on lightweight concrete added Colombian expanded clay aggregate. It was found that the inclusion of up to 50% of the Colombian expanded clay aggregate causes a 15% workability decrease, 36% compressive strength decrease, 22% apparent density decrease as well as 34% decrease in the chloride migration coefficient of the lightweight concrete. In the same way, the lightweight concrete added with 50% of Colombian expanded clay aggregate meets the lightweight concrete requirements prescribed by the ACI 318 building code in terms of compressive strength, and unit weight. From the results, it is concluded that the use of Colombian expanded clay aggregate added up to 50% by weight of conventional aggregate is feasible to manufacture structural lightweight concrete. [ABSTRACT FROM AUTHOR]

Concrete in the construction industry is a widely used material, so there has been research on how to innovate the materials that are usually used for the production of concrete, but without altering the mechanical properties, that is to say that they are equal or better than they usually are; so using recycled material is a good option because it would help to reduce pollution, reduce the use of raw materials and improve the environmental situation. The objective of this article is to review different research on a material called tire steel fibers incorporated in concrete, which allows improving the properties of workability, compressive strength, flexural strength and density of concrete. A search of 80 review articles indexed in different databases was performed, in addition to being published research from the last 7 years between 2015 and 2021, which are divided as follows: 14 from ScienceDirect, 21 from EBSCO, 20 from Sopas and 24 from Web Of Scince, documents that point out the importance of sustainable construction and the description of recycled tire steel fibers. The steps, methods and techniques of selection, characteristics and adequate volume that the fiber should have were reviewed, after discussing and analyzing the results, it is concluded that recycled tire steel fibers cause positive effects on the mechanical characteristics of concrete. [ABSTRACT FROM AUTHOR]