Effects of Relative Humidity and Temperature on the Drying Shrinkage of Roller-Compacted Concrete Pavements

Roller-compacted concrete (RCC) pavements have been the subject of studies focused on their increasing deterioration over time due to the influence of vehicular loading and ambient factors in humidity and temperature conditions ranging from medium to low (40% relative humidity and 25 ºC temperature). Therefore, it is necessary to understand how they behave under various relative humidity and temperature conditions since these parameters vary in each geographic region. In this context, this research focused on analyzing the effect of drying shrinkage on RCC pavements under the influence of vehicular loading using a computational model calibrated with data obtained under typical ambient conditions. For this purpose, laboratory experiments were performed, numerical modeling was used, and the results for RCC pavements were validated using statistical analysis. The results revealed validated models providing moisture content and drying shrinkage curves. These results also underline the importance of considering ambient effects when calculating pavement stresses as a response variable in structural designs. In particular, these effects are highlighted as they can generate changes in pavement stresses of up to 10%, emphasizing the relevance of the models proposed in this study as they consider this phenomenon when predicting the performance and durability of RCC pavements

Prediction of the Physical-Mechanical Properties of Roller-Compacted Concrete Pavements under Different Service and Mix Conditions Based on Cement and Water Content

Roller-compacted concrete (RCC) for pavements has experienced problems with its physicalmechanical performance over extended periods due to ambient and in situ curing conditions. Accordingly, this study aimed to present multiple regression equations for calculating the physicalmechanical properties of RCC for pavements under different service and mix conditions. For this purpose, the research included two cement and two water contents, one reduced with admixture, and four combinations of temperature and relative humidity. For model calibration and definition of the equations, cubic and beam samples were fabricated to carry out physical-mechanical tests, such as moisture content, shrinkage, and modulus of rupture. Laboratory-obtained data were studied with the Response Surface Methodology (RSM) to determine the best regression equations. The main findings determined that the behavior of a mixture of RCC at a prolonged ambient exposure time is possible because the surface models and the RSM were consistent with the different service and mix conditions. The models showed an accuracy of 98.99% in detecting shrinkage changes from 12 to 16% cement with 5.65% water in dry to wet ambient conditions. Similarly, moisture content and modulus of rupture had a 98.27 to 98.88% fit. Finally, the drying shrinkage, with mixes of 12% cement and water content variations with water-reducing admixture and superplasticizer effects, had an adjustment of 94.87%

Study of Surfactant Additives for the Manufacture of Warm Mix Asphalt: From Laboratory Design to Asphalt Plant Manufacture

Warm Mix Asphalt (WMA), manufactured at a lower temperature than the traditional Hot Mix Asphalt (HMA), allows for important economic and environmental benefits when considered for application in roads. Nonetheless, despite the benefits, its application in pavement for roads is not as widespread as desired from an environmental point of view; more in-depth studies to investigate its development and wider applicability are required. Thus, the present paper aims to contribute to the implementation of this cleaner technology to produce WMA (based on chemical additives) for its application in pavement for roads, including from the stage of the design of the material in the laboratory (by selecting the most appropriate manufacturing temperature and additive type and dosage) to its production in a conventional industrial plant for its use in a trial section. Results demonstrate that it is possible to reduce the manufacturing temperature of asphalt mixtures by using chemical additives, recording similar mechanical behaviour (or even superior) to conventional hot mixtures when specific studies are developed for the optimal design of the WMA. It was also shown that these mixtures could be produced in a conventional asphalt plant without implementing important changes in equipment, which implies a cost-effective solution that can readily be incorporated into traditional plant procedures

A Critical Review of Sensors for the Continuous Monitoring of Smart and Sustainable Railway Infrastructures

Real-time and continuous monitoring through smart sensors is considered to be the evolution of traditional track testing, enabling the earlier detection of the main failure modes that degrade railway tracks. Through carrying out preventive maintenance operations, infrastructure resources may be optimized, leading to smarter and more sustainable infrastructure. For this reason, under the larger goal of creating a synergy with various types of sensors for railway tracks, this article presents a critical review on the di erent, currently available sensors for smart and continuous monitoring. Specifically, the most appropriate monitoring technologies for each of the main railway track failure modes have been assessed and identified, thus deriving the advantages and capacities of each solution. Furthermore, this review presents some of the main experiences carried out to date in literature by using sensor technologies, such as strain gauges, piezoelectric sensors, fiber-optics, geophones and accelerometers. These technologies have proven to o er appropriate characteristics and accuracy for the continuous monitoring of a railway track’s structural state, being capable of measuring di erent parameters, such as deflections, deformations, stresses or accelerations that would permit the technical tracking of various forms of degradation

Reuse of Zeolite By-Products Derived from Petroleum Refining for Sustainable Roads

The reduction in consumption of natural resources (fuel, gas, etc.) and contaminant emissions (CO2, CO, NOx, etc.) during the production of asphalt mixtures has become one of the main challenges in road engineering. Warm mix asphalts (WMAs) have been developed in order to achieve this objective while ensuring the mechanical performance and durability of traditional hot mix asphalts (HMAs). However, these materials are commonly manufactured using additives or products whose production could reduce both their environmental benefits and cost effectiveness. /is paper presents a research study that aims to analyse the reuse of zeolite wastes derived from petroleum refining in the production of warm mix asphalts. For this purpose, two different types of zeolite wastes were analysed as additives for the manufacture of two warm mix asphalts, whose mechanical performance was compared with conventional WMA and hot mix asphalt. /e results indicate that zeolite wastes with a lower particles size presented higher capacity to absorb water, while its dosage at 0.3% allows for producing warm mix asphalts at temperatures around 145°C, with comparable workability and densification to conventional HMA at 165°C without reducing its bearing capacity, fatigue life, and resistance to water action and plastic deformation.“Soluciones de Pavimentación Ecológicamente Sostenibles: Ecoasfaltos” funded by the Ministry of Economy and Knowledge of Andalusia and the Ministry of Economy and Competitiveness of Spain in the framework of CTA (Corporación Tecnológica de Andalucía)

An analysis of the performance of deconstructed tires for use as pads in railroad tracks

The use of end-of-life (EOL) tires is now widespread in civil engineering work. In most cases, the tires are shredded and recycled as crumb rubber. However, this research focuses on an alternate method in which EOL tires were deconstructed to manufacture rail pads. In other words, their outer layer was removed, which made it possible to benefit from the mechanical properties of the tires without having to grind them up. The performance of the recycled tire rubber was analyzed by means of static and dynamic stiffness tests as well as by fatigue tests. The results reflected the long-term performance of the material. Also analyzed was the deterioration of its properties after various thermal and anti-ageing treatments. The results obtained were compared with those of commercial crumb rubber rail pads. The excellent performance of the rail pads made from deconstructed EOL tires shows the high potential of this material for use in railroad tracks

The Use of Deconstructed Tires as Elastic Elements in Railway Tracks

Elastic elements such as rail pads, under sleeper pads and under ballast mats are railway components that allow for a reduction in track deterioration and vibrations. And they are furthermore commonly used to obtain an optimal vertical stiffness of the infrastructure. However, the use of elastomeric materials can increase construction costs and the consumption of raw materials. Thus, the utilization of used tire layers offers an alternative to reuse an abundant waste reducing the cost of elastic elements. In addition, an innovator technique allows deconstructing tire layers without grinding up the material, reducing production costs at the same time that tire properties are remained. This research is focused on the study of the viability of developing elastic components from used tire layers by evaluating the influence of thickness, the resistance capacity of the elements and their behavior in a ballast box. Results indicate the ability of tire pads to manufacture elastic elements (rail pads, under sleeper pads and under ballast mats) to be used in railway tracks.Authors want to thank to the Ministry of Economy and Competitiveness of Spain for the support received to develop the project entitled ―Design of used tire pads to be utilized as anti-vibration systems in railway tracks‖, IPT-2011-1963-310000

Servicios eco sistémicos brindados por Tabebuia rosea (Bertol.) DC. Centro, Tabasco, México

El presente trabajo se realizó en la División Académica de Ciencias Biológicas de la UJAT,   con la finalidad de registrar los  servicios ambientales que genera el macuilíz. Esta especie reviste gran importancia ecológica, económica y cultural. Este estudio permitió, conocer los bienes y servicios que esta especie aporta dentro de la División. Para ello se planteó identificar y evaluar losservicios ecosistémicos que brinda esta especie en la DACBiol-UJAT, durante el año 2017. El trabajo se dividió en tres partes: Primero, revisión bibliográfica, segundo, trabajo de campo; dividido en 7 etapas; 1) censo, 2) premuestreo, 3) marcaje, 4) medición, 5) monitoreo, 6) servicios ambientales y 7) etapas reproductivas; y tercero trabajo de gabinete. Los bienes y servicios registrados fueron: alimento, regulación de la temperatura, polinización, anidación, nidación, hábitat, refugio, percha, descanso, generación de materia orgánica, sombra y belleza escénica. Se registraron cuatro grupos taxonómicos de fauna que hacen uso de los bienes que genera esta especie: aves, insectos, mamíferos y reptiles; los grupos que registraron mayor riqueza fueron las aves seguido por el grupo de insectos. Se registró una temperatura mensual que va de 28.6 hasta los 34.7°C y en sombra reduce la temperatura de 26 a 30 °C. Se registraron los servicios ecosistémicos que brinda Tabebuia rosea en la zona de estudio; estos servicios se dividieron en cuatro categorías: servicios de provisión, regulación, soporte y cultural. Además, benefician a la diversidad biológica que se sustenta, resguarda y habita en el nicho ecológico que provee esta especie

Servicios eco sistémicos brindados por Tabebuia rosea (Bertol.) DC. Centro, Tabasco, México

El presente trabajo se realizó en la División Académica de Ciencias Biológicas de la UJAT,   con la finalidad de registrar los  servicios ambientales que genera el macuilíz. Esta especie reviste gran importancia ecológica, económica y cultural. Este estudio permitió, conocer los bienes y servicios que esta especie aporta dentro de la División. Para ello se planteó identificar y evaluar losservicios ecosistémicos que brinda esta especie en la DACBiol-UJAT, durante el año 2017. El trabajo se dividió en tres partes: Primero, revisión bibliográfica, segundo, trabajo de campo; dividido en 7 etapas; 1) censo, 2) premuestreo, 3) marcaje, 4) medición, 5) monitoreo, 6) servicios ambientales y 7) etapas reproductivas; y tercero trabajo de gabinete. Los bienes y servicios registrados fueron: alimento, regulación de la temperatura, polinización, anidación, nidación, hábitat, refugio, percha, descanso, generación de materia orgánica, sombra y belleza escénica. Se registraron cuatro grupos taxonómicos de fauna que hacen uso de los bienes que genera esta especie: aves, insectos, mamíferos y reptiles; los grupos que registraron mayor riqueza fueron las aves seguido por el grupo de insectos. Se registró una temperatura mensual que va de 28.6 hasta los 34.7°C y en sombra reduce la temperatura de 26 a 30 °C. Se registraron los servicios ecosistémicos que brinda Tabebuia rosea en la zona de estudio; estos servicios se dividieron en cuatro categorías: servicios de provisión, regulación, soporte y cultural. Además, benefician a la diversidad biológica que se sustenta, resguarda y habita en el nicho ecológico que provee esta especie

High-Performance Sustainable Asphalt Mixtures for High-Volume Tra c Roads in Severe Climates

This paper summarizes the work carried out in a research project whose main objective was to develop high-performance sustainable bituminous materials (using crumb rubber and additives to reduce their manufacturing temperature) to be used in roads that support high tra c volumes and/or severe environmental conditions. For this purpose, various studies were conducted both in a laboratory and in a real asphalt plant (at binder and mixture level). Later, these materials were used to construct a trial section in a highway at a mountain pass (at more than 1400 m above sea level) supporting more than 2600 heavy vehicles each day under severe environmental conditions (snow during winter, and high temperatures and many hours of solar radiation during the summer). The results indicate the viability of using these materials, since they provide a number of advantages such as improved workability at lower temperatures and an increase in the mechanical resistance against the main sources of distress that a ect asphalt pavements