Search

This research study focused on the design of under sleeper pads made from deconstructed end-of-life tires. The rubber was obtained without grinding up the tires. This cost-effective process has a lower environmental impact and at the same time preserves the mechanical characteristics of the material. The analysis was focused on how certain design parameters of the under sleeper pads affected their static performance (at different stress levels) and their dynamic performance (at different load frequencies). Their long-term performance and durability were also evaluated with a mechanical fatigue test. In addition, a ballast box was used to assess the impact of the pads on lateral resistance and stress distribution in a ballasted railway track system. The results of this study showed that under sleeper tire pads with different static and dynamic stiffness moduli can be obtained by varying pad thickness and by applying different physical treatments to the material. Moreover, the fatigue results revealed that these tire pads are suitable for use in railway systems. In addition, it was found that the pads distributed loads to a higher ballast area and at the same time increased the lateral resistance of the track.

Deconstructed end-of-life tires are an abundant waste material that can be used to manufacture rail pads. Since tire layers are deconstructed, there is no need to shred and grind them up, which has the advantage of reducing economic costs as well as environmental impacts. However, the mechanical performance of this material can be affected by various design parameters, particularly, the thickness of the rail pad. This research study assessed the impact of thickness on the mechanical performance of deconstructed tire rail pad when subjected to loads simulating the passing of trains. The objective was to produce rail pads specifically designed for railway systems of various types and demands. Accordingly, the static and dynamic response was evaluated as well as the fatigue strength of rail pads of different thicknesses. In this sense, thicker rail pads were found to be more flexible and with a greater capacity to damp loads. The results of the study showed that for high-speed railways, the most suitable rail pads were those with a thickness of 7.5–9.0 mm, whereas pads with a lesser thickness were more suitable for conventional railroad tracks.

Fatigue cracking is one of the most common distresses that affect roads all over the world. The development of new techniques that allow minimizing the effect caused by this pathology is crucial to reduce road rehabilitation costs. For this purpose, a new product obtained from deconstructed tires has been designed and tested “anti-reflective cracking mats”. Manufactured from the resistant layers of the tyre (metallic and textile layers), it is used as a system placed between the courses of the pavement in order to reduce the effect caused by fatigue cracking processes. This article presents the characteristics of these products and resumes their mechanical performance in a pavement section tested in laboratory. The results obtained showed that the application of these anti-reflective cracking systems could be an interesting solution in order to reduce the impact caused by this pathology.

Asphalt pavement properties (strength, durability, bearing capacity, etc.) are considerably affected by environmental conditions. Because of this fact, regions with severe climates (high thermal gradients, abundant precipitation, presence of freeze-thaw cycles, solar radiation, etc.) have serious problems in maintaining the functional integrity of these infrastructures. Thus, it is necessary to develop new materials that could extend the service life of these pavements without increasing the construction costs. Accordingly, the present paper studies the improvement of the mechanical performance of high-modulus asphalt mixtures through the addition of acrylic fibers, for their use under severe environmental conditions. For this purpose, different tests were carried out [thermal stress restrained specimen test, immersed wheel-tracking test, freeze-thaw sensitivity test, and UGR-FACT (University of Granada-Fatigue Asphalt Cracking Test)] under variable conditions (simulating cold and hot scenarios). ...

El presente documento describe la implementación de acciones en cooperación con Universidades Centroamericanas en relación con la Universidad de Alcalá, España, específicamente con lo relacionado con las actividades implementadas en el marco del PROGRAMA UNIVERSITARIO DE DESARROLLO LOCAL con la finalidad de establecer la vinculación con el territorio. Además se presenta esta metodología como un aporte de la academia ante los impactos del cambio climático, pues es de vital importancia el aporte de las escuelas de educación superior en cuanto a la innovación para promover la resiliencia como estrategia para disminuir el impacto del cambio climático. Se plantea algunas conclusiones y los pasos seguidos para impactar los territorios.

The use of modified binders plays a very important role in the construction of more durable pavements. However, the addition of modifiers to the binders could considerably increase their cost, making these materials less competitive. Thus, in recent years, various research studies have been carried out to obtain new modified binders that could lead to an improvement in the mechanical performance of asphalt pavements without a notable increase in their construction costs. To this end, the reuse of wastes and by-products from other industries has been posited as an interesting and sustainable alternative. This study investigates the reuse of scraps from reclaimed geomembranes composed of low-density polyethylene and polyester fibers as modifiers for asphalt binders. For this purpose, different blends of this waste and neat bitumen were manufactured and tested [penetration, softening point, storage stability, frequency sweep, multiple stress creep-recovery (MSCR), and time sweep tests). In addition, ...

Fatigue cracking is considered to be one of the main pathologies in asphalt pavements, contributing to the reduction of its service life and generating high costs as a consequence of more m...

En este estudio se evalúo la rentabilidad económica y la captura de Carbono del sistema agroforestal cacao entre tres parcelas de diferentes edades. Se aplico un cuestionario estructurado a 36 productores pertenecientes al poblado C-34 de Huimanguillo, Tabasco. Se evaluaron los egresos e ingresos en términos monetarios de la plantación del cacao. Para la determinación de la captura de Carbono se estudiaron nueve sitios con superficie de tres hectáreas cada uno pertenecientes al poblado C-34 y un sitio ubicado en el Km-21 del campo experimental del Colegio de Postgraduados. Para la cuantificación de Carbono, se utilizo la metodología rápida para la estimación y monitoreo de captura de carbono propuesta por Rendón y Soto, 2007. Para el análisis estadístico se utilizo un análisis ANOVA y una prueba Tukey Kramer. La plantación de cacao de 20 años obtuvo la mayor utilidad con $ 7 653 ± $ 3 921, mientras que la plantación de cacao de 30 años obtuvo la menor utilidad promedio con $ 5 899 ± $ 3 420. El análisis estadístico demostró que no hubo diferencias estadísticas significativas en relación al Carbono capturado en las parcelas evaluadas; Sin embargo, en las plantaciones de cacao de 15 años de edad se obtuvo un valor promedio 100.6 ± 110.5 t/C/ha-1 mientras que en las de 20 años se obtuvo 49.9 ± 14 t/C/ha-1.

Bituminous mixtures are visco-elastic materials whose mechanical performance is highly influenced by temperature. In addition, during their service life, these type of materials suffer an ageing process which induce an increase in bitumen viscosity and therefore, a variation in the response of the mixture. The changes produced by these phenomena are mainly manifested in terms of stiffness, which could exert a considerable influence on the fatigue cracking resistance of asphalt materials. In this respect, this paper attempts to provide a better understanding of the effects caused by temperature and ageing on the resistance of bituminous mixtures to the propagation of cracking phenomena. For this purpose, the rheological response of the binder has been correlated with the mechanical performance offered by the bituminous mixture.

Esta investigación aborda la temática de Educación para la Paz. Responde a un enfoque cualitativo, de campo, investigación acción participante, de carácter reflexivo, crítico. Su propósito fue el estudio comparativo de la agresividad en tres escuelas del Estado Lara, Venezuela. Se realizó un diagnóstico y se formuló, aplicó y evaluó un Plan de Acción sustentado en la interacción social para minimizar el comportamiento agresivo. El estudio se apoya en Bandura (1981) y Rogers (1984). Los actores fueron 90, organizados en nueve grupos; tres por escuela, conformados por docentes, estudiantes, padres y representantes. Las técnicas de recolección de información fueron la observación participante, la entrevista a profundidad y las notas de campo. Los resultados arrojaron un alto nivel de agresividad en 90% de los actores. Con la intervención realizada se fortaleció en el educando un desarrollo social justo, equilibrado, humano, para que viva dentro de los valores de solidaridad humana, y mejorar la convivencia de docentes, estudiantes, padres y representantes, dando sentido a sus proyectos de vida.

El presente trabajo se realizó en el ejido las coloradas, Cárdenas, Tabasco, con el objetivo de cuantificar el volumen maderable del mangle negro (Avicennia germinans (L.) L., afectado y muerto por la oruga de Anacamptodes sp., durante 2010-2011. Se establecieron 10 unidades de muestreo (UM) de forma rectangular de 20 x 50 m para evaluación permanente. Se registró el estado sanitario de los árboles, el diámetro a la altura del pecho (DAP 13 m), la altura total y altura del fuste limpio (Ht y Hfl). Se calculó el área basal (AB m2ha-1), Volumen total y del fuste limpio (Vt y Vfl m3ha-1) y se estimó la densidad de árboles por especie. Los valores obtenidos se arreglaron en clases diamétricas con una amplitud de 5 cm. Se realizó un análisis de correlación lineal simple entre la altura y el DAP. En total se evaluaron 1,831 árboles de tres especies, tres géneros y tres familias botánicas. El mangle negro representó 99.6% del total de árboles evaluados; la densidad varió de 750 hasta 2,520 árboles por ha-1. El 42.9% de los árboles registrados mostraban partes vivas y el 57.1% estaban totalmente muertos. Específicamente, el mangle negro registró un Vt de 68.3 m3 ha-1, Vfl de 24.6 m3 ha-1y un AB de 12.4 m2 ha-1. La categoría de 5 - 9.9 cm de DAP registró el 45% de los árboles identificados. La correlación del DAP y la altura del mangle negro, fue moderada positiva significativa (r² = 0.5313, p = 2.2 e-16).

Hot bituminous mixtures are becoming widely used in modern railway tracks in the sub-ballast layer. The reason is that these materials allow for both an increase in bearing capacity and greater protection of the substructure respect the traditional granular sub-ballast. Despite these advantages, the fact that these materials are manufactured at a temperature of 160°C means that their application can lead to an important increase in construction costs, pollution and energy consumption. This paper aims to study the possibility of using WMA manufactured at lower temperatures, as bituminous sub-ballast, in order to save energy and reduce emissions throughout the production process, as well as diminish the global costs of this layer. To this end, this study focuses on a comparison of the mechanical behaviour of warm and hot bituminous mixtures as sub-ballast under various loading conditions. The results indicate that WMA offers mechanical behaviour that is comparable to conventional HMA. Las mezclas bituminosas en caliente en infraestructuras ferroviarias son una alternativa cada vez más extendida en vías de altas prestaciones, para mejorar la capacidad portante de la vía y el grado de protección del resto de la subestructura. Sin embargo, el sub-balasto bituminoso presenta una serie de limitaciones asociadas al posible incremento de costes de construcción y a problemas medioambientales derivados de la utilización de mezclas bituminosas en caliente fabricadas a 160°C. Este trabajo, tiene como objetivo estudiar la posibilidad de utilizar WMA fabricado a temperaturas inferiores, como sub-balasto bituminoso con el fin de ahorrar energía, reducir las emisiones y disminuir los costes constructivos de esta capa. Así, este estudio se centra en la comparación entre el comportamiento mecánico de mezclas bituminosas semicalientes y calientes como sub-balasto, bajo diferentes condiciones de carga. Los resultados muestran que el sub-balasto semicaliente presenta una respuesta mecánica comparable a las soluciones convencionales.