Influence of the diatomite specie on the peak and residual shear strength of the fine-grained soil

Diatomite is a powdering mineral mainly composed of diatom microfossils present in marine and lacustrine soils, which influences their physical and mechanical properties. Although many articles have been found in the literature concerning the influence of diatomite in the overall behavior of natural soils, few research efforts have been carried out to evaluate the influence of the diatom microfossil species on their shear resistance. Therefore, in this research, the influence of the diatomite species and the content in the peak and the residual shear strength of diatomite-fine grained soil mixtures was analyzed using the annular shear strength test. Scanning electron microscopy (SEM) and Atterberg limits were also carried out as additional tests to explain the interlocking effect between the microfossils and the soil. Overall, both diatomite species increased both peak and residual shear strength of the soil similar to dense sands. Nevertheless, the Mexican species reveal higher friction angle values compared with Colombian species

Medición de la conductividad hidráulica bajo trayectorias horizontales en suelos granulares

In geotechnical structures, the permeability-dependent stability analysis is generally evaluated under vertical trajectories, because most permeameters are configured so that the water passes through the porous medium in this way. However, it is clear from the physical point of view that water can flow along different paths, including preferential ways that can include horizontal trajectories, parallel to the deposit of the stratum. The foregoing implies that both the vertical and horizontal component of the hydraulic conductivity or permeability coefficient must be estimated for a given stratum. The current research aims to explore possibilities for measuring the coefficient of permeability in horizontal trajectories, on granular soils, under a constant condition of relative density. For this purpose, a special chamber attached to a constant head permeameter was designed and constructed, which allows to measure the permeability in conditions of horizontal flow parallel to the soil layers. The proposed camera also admits the estimation of the permeability coefficient by combining stratifications of different granular soils, where the trajectories are not perfectly horizontal, but have diagonal paths. The results are compared with data obtained by conventional vertical flow permeameters, in order to check the difference in the measurements considering both situations in the samples. As a conclusion, it is important to report that there is evidently a difference in the permeability coefficients measured under different trajectories,En las estructuras geotécnicas generalmente el análisis de estabilidad dependiente de la permeabilidad, es evaluado bajo trayectorias verticales, debido a que la mayoría de permeámetros están configurados para que el agua atraviese de esta manera el medio poroso. No obstante, es claro desde el punto de vista físico que el agua puede fluir siguiendo diferentes caminos, entre ellos recorridos preferenciales que pueden incluir trayectorias horizontales paralelas a la depositación del estrato. Lo anterior implica que se debe estimar para un estrato, tanto la componente vertical, como horizontal de la conductividad hidráulica o coeficiente de permeabilidad. En la investigación actual se pretende explorar posibilidades de medición del coeficiente de permeabilidad en trayectorias horizontales, en suelos granulares, bajo una condición constante de densidad relativa. Para ello se diseñó y construyó una cámara especial adosada a un permeámetro de cabeza constante, que permite medir la permeabilidad en condiciones de flujo horizontal paralelo a los estratos. La cámara propuesta admite también, la estimación del coeficiente de permeabilidad combinando estratificaciones de diferentes suelos granulares, donde las trayectorias no son perfectamente horizontales, sino presentan recorridos diagonales. Los resultados son comparados con datos obtenidos mediante permeámetros convencionales de flujo vertical, con el fin de comprobar la diferencie en las mediciones considerando ambas situaciones en las muestras. Como conclusión generar es importante reportar que evidentemente existe una diferencia en los coeficientes de permeabilidad medidos bajo diferentes trayectorias

Study of the effect of polyolefin-aramid fibers on PA mixture

The present research seeks to investigate the performance of a PA mixture reinforced with polyolefin-aramid fibers. The functional and mechanical performance of the mixture was assessed by different volumetric and mechanical tests including total air voids, interconnected air voids, Cantabro particle loss in dry and wet conditions and binder drainage test.This research is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 769373

An integrated DoE - Stochastic multi criteria decision-making analysis applied for experimental evaluation of fiber reinforced porous asphalt mixtures

Porous asphalt (PA) mixture offers multiple benefits such as noise mitigation, skid resistance and management of storm water and runoff quality. However, its durability is not as promising compared to dense-graded asphalt mixtures. The objective of this research is to evaluate the functional and mechanical performance of PA mixtures modified with nylon and hydrated lime through experimental tests including air voids, permeability, raveling resistance, moisture susceptibility and binder drain down. Taguchi approach was employed to analyze the performance of these responses. Additionally, a novel multi-criteria decision-making (MCDM) technique was employed to turn the multiple-response problem optimization into a single response problem optimization. Monte Carlo Stochastic simulations were included as a complement to deal with the uncertainty contained in the experimental quantitative data. The optimal levels for acquiring a proper overall response value in terms of functionality and durability were identified as 4.60% for binder content factor; 0.04% for fiber content factor and 1.50% for Hydrated Lime content factor

Determination the coefficients of San’s model, to calculate the percentage of removal flocculent particles with three coagulants types

This study calculated coefficients for the model elaborated by Hasan Ali San in 1989 based on the percentage of flocculated particles removed by three coagulants commonly used for water purification. The coagulants used were type A aluminum sulfate, type B aluminum sulfate and ferric chloride. An experiment was designed to study water with initial turbidity between 25 and 30 Nephelometric Turbidity Units (NTU). The experiment consisted of filling a sedimentation column with water and colloid particles which were agitated rapidly and then slowly with compressed air. This allowed the percentage of particles removed from the remaining turbidity to be determined at different times and different depths by measuring sedimentation of the flocculated particles. Once percentages of material removed had been calculated, an isoconcentration graph was elaborated and multiple linear regression was used to determine the coefficients of the model proposed by SanEl objeto de esta investigación es determinar los coeficientes del modelo de San para calcular el porcentaje de remoción de las partículas floculentas, al utilizar tres de los coagulantes más comúnmente utilizados en la potabilización del agua. Para ello se realizaron pruebas de laboratorio que comprenden el estudio de un agua problema, la cual presenta una turbiedad inicial en un rango comprendido entre 25 y 30 UNT. Los coagulantes utilizados para el desarrollo de la prueba fueron: sulfato de aluminio tipo A, sulfato de aluminio tipo B y cloruro férrico. El experimento consiste en llenar la torre de sedimentación con las partículas floculentas generadas después de una agitación con aire comprimido, de tal manera que se genere la mezcla rápida y lenta; lo que permite que posteriormente mediante el proceso de sedimentación de las partículas floculentas, se determinen a diferentes tiempos y diferentes rangos de profundidad, el porcentaje de remoción de las partículas a partir de la turbiedad remanente. Con los porcentajes de remoción calculados se elabora una gráfica de isoconcentración y se realiza una regresión lineal múltiple para determinar los coeficientes del modelo propuesto por San en 198

Measurement of hydraulic conductivity under horizontal paths in granular soils

In geotechnical structures, the permeability-dependent stability analysis is generally evaluated under vertical trajectories, because most permeameters are configured so that the water passes through the porous medium in this way. However, it is clear from the physical point of view that water can flow along different paths, including preferential ways that can include horizontal trajectories, parallel to the deposit of the stratum. The foregoing implies that both the vertical and horizontal component of the hydraulic conductivity or permeability coefficient must be estimated for a given stratum. The current research aims to explore possibilities for measuring the coefficient of permeability in horizontal trajectories, on granular soils, under a constant condition of relative density. For this purpose, a special chamber attached to a constant head permeameter was designed and constructed, which allows to measure the permeability in conditions of horizontal flow parallel to the soil layers. The proposed camera also admits the estimation of the permeability coefficient by combining stratifications of different granular soils, where the trajectories are not perfectly horizontal, but have diagonal paths. The results are compared with data obtained by conventional vertical flow permeameters, in order to check the difference in the measurements considering both situations in the samples. As a conclusion, it is important to report that there is evidently a difference in the permeability coefficients measured under different trajectorie