Examinando por Materia "Asphalt"
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Ítem Comportamiento de tejas de cubierta tipo multicapa fabricadas con asfalto crudo y modificado cuando son sometidas a cargas constantes(Universidad EAFIT, 2011) López Bula, Pedro Javier; Múnera Ossa, Juan CamiloEl presente trabajo, analiza las propiedades viscoelasticas de diferentes materiales asfalticos después de ser sometidos a cargas permanentes y a diferente temperatura -- Estas cargas simulan las que eventualmente se pueden presentar en la aplicacion y fabricación de productos asfalticos ampliamente utilizados en el sector de la construcción -- Para este estudio se utilizó asfalto crudo y modificado con diferentes polímeros: Cera de polietileno (CERA), caucho molido de llanta (CR), copolimero de estireno – butadieno - estireno (SBS), fueron los aditivos poliméricos utilizados como modificadores del asfalto, tanto el asfalto crudo como las diferentes mezclas fueron sometidas a ensayos creep con cargas constantes de 10 N, 60 N, 110 N, 160 N y 210 N -- Con el fin de determinar la dependencia del comportamiento del asfalto crudo y modificado respecto a la temperatura, se desarrollaron ensayos a tres diferentes temperaturas: Ambiente (aprox. 23°C), 30°C y 40°C -- Entre los resultados obtenidos, se destaca que la menor deformación de los materiales en cuestión la presentó el asfalto modificado con CERA al 6 %, seguido del asfalto modificado con CERA al 3 %, asfalto modificado con SBS al 6 %, asfalto modificado con SBS al 3 %, asfalto modificado con CR al 3 % y finalmente, el asfalto modificado con CR al 6 % a temperatura ambiente -- Mientras, que al aumentar la temperatura a 30 °C y 40 °C, se presenta el caso contrario en cuanto a deformación de los materiales, siendo los asfaltos CR 6 % y SBS 3 % los que mejor comportamiento presentaron durante todo el ensayo -- Los materiales con mejor comportamiento serán propuestos como material base para la fabricación de prototipos de tejas a nivel industrialÍtem Emulsiones asfálticas con adición de Nanosílice(Universidad EAFIT, 2023) Calonge Vargas, Edgar Arturo; Vidal Valencia, JuliánThe objective of this research is to analyze the reaction of asphalt emulsions to the incorporation of nanocomposites to improve their properties and characteristics. For this purpose, tests were carried out with conventional asphalt emulsions CRL-1 and CRR-1 in which 5% and 10% of liquid nanosilica were added, by virtue of the weight of each sample, which was subjected for one hour at an agitation speed of 250 RPM at room temperature of 23 °C. Thus, it could be appreciated in the results obtained, that nanosilica changes its properties, so that such component becomes a fundamental alternative to generate materials with much more sustainable specific properties.Ítem Envejecimiento termo-oxidativo de asfaltos(Universidad EAFIT, 2014) Gamarra Escamilla, AdrianaÍtem Estudio de mezclas binarias Asfalto-Polímero(IMPRENTA UNIV ANTIOQUIA, 2014-01-01) Múnera, J.C.; Alexander Ossa, E.; Múnera, J.C.; Alexander Ossa, E.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaBitumen is a black material composed of a mixture of various natural hydrocarbons. Bitumen has been commonly used in road paving and roofing applications thanks to its hydrophobic and adhesives properties. The production of Polymer Modified Bitumens (PMB) has allowed the development of materials with better performance in comparison to pure bitumen. This work presents the effect of addition of polymer to a Colombian bitumen from its morphological, rheological and thermal properties, in order to identify different modification levels. The polymers used as modifiers were polyethylene wax (CPE), styrene butadiene styrene (SBS) and crumb rubber (CR). They were added to bitumen in proportions between 3 to 15% w/w. Both neat bitumen and PMB were characterized by penetration and softening point. Thermal and rheological characteristics were analyzed by differential scanning calorimetry (DSC) and rotational rheometry, respectively. Changes in the morphology were measured by atomic force microscopy (AFM). The experimental results showed that the CPE mixtures had the most pronounced effect on the conventional properties, achieving a 75% reduction in penetration and a 250% increase in the softening point compared to neat bitumen. The results obtained by DSC allowed identifying three glass transition temperatures (Tg) in neat bitumen. Mixtures with SBS altered Tg, showing changes on the thermal characteristics of neat bitumen. Mixtures with CPE and SBS showed the highest values of G*. The results obtained by AFM help identifying three different phases in neat bitumen and its variation with the addition of different polymer modifiers, showing considerable structural changes that led to changes in the material properties at the macroscopic level.Ítem Implementación de pruebas de indentación esférica en asfaltos(Universidad EAFIT, 2011) Giraldo Beltrán, Natalia; Maldonado Estrada, Natalia María; Vidal Valencia, JuliánLos pavimentos son diseñados para proveer una superficie de rodadura suave, cómoda y duradera con una adecuada resistencia al deslizamiento, de una manera económica a lo largo de su vida útil -- Para cumplir estos requerimientos, la base, sub-base y capas que subyacen son protegidas del tráfico y los efectos ambientales mediante la utilización de un material superficial que no sufra un deterioro inaceptable; siendo una de las opciones de material superficial más comunes en nuestro medio, el uso de pavimentos asfálticos -- Existen diferentes formas en las que un pavimento asfáltico puede fallar, las más comunes son fractura por fatiga, deformación permanente, reducción de la resistencia al deslizamiento y fractura a temperaturas bajas -- La deformación permanente, es el defecto producido en el material asfáltico que no presenta falla estructural; la predicción de este tipo de defecto se dificulta por la alta complejidad del material, que presenta comportamiento viscoelastoplástico no lineal, y los métodos comúnmente utilizados para su análisis son altamente complejos, lo que hace difícil su utilización en la práctica del día a día -- Además, para utilizar estos métodos de análisis se requiere un buen número de pruebas destructivas de laboratorio que muchas veces no logran reproducir las mismas condiciones ambientales y de soporte que se encuentran en las vías -- Se hace necesario entonces contar con un modelo simple y de fácil implementación para predecir la deformación permanente de estos materiales y así reducir el número y periodicidad de mantenimientos en las vías -- En este proyecto se caracterizan a nivel de laboratorio el asfalto como material comúnmente utilizado en la construcción en Colombia, ajustándolo a parámetros de un modelo constitutivo para la predicción del efecto de deformación permanente sobre dicho materialÍtem Indentación esférica en asfaltos envejecidos(Universidad EAFIT, 2022) D paola Puche, Plinio; Vidal Valencia, JuliánPermanent deformation is one of the most frequent failures produced in the asphalt pavement, mainly in heavy and low-speed traffic lanes. Predicting this type of defect is made difficult by the high complexity of asphalt, since it is a thermoplastic material that exhibits linear viscoelastic behavior at low loads and nonlinear viscoelastic behavior at high loads. Its behavior also varies due to oxidative aging, produced by environmental effects throughout its useful life, which makes its prediction more complicated. The tests used for its analysis are highly expensive and often require a large number of destructive laboratory tests, which sometimes fail to reproduce the same environmental and support conditions of the tracks. In this work, it is proposed to use the spherical indentation method, for asphalts aged by the mechanical agitation test at high revolutions, which are economic tests that use easily accessible equipment for any pavement laboratory, such as the manual penetrometer (previously established for spherical indentation calculations) and a conventional double helix mechanical stirrer (used in the oxidative aging process). This method was used in a conventional asphalt AC 60-70, aged in times of 30 min, 1 hour, 1.5 hours, 2 hours, 2.5 hours and 3 hours, in order to determine the variation of its properties as it increases. the effect of aging.Ítem Modeling and analysis of susceptibility to permanent deformation in asphalt mixtures(Pontificia Universidad Católica de Chile, 2011-01-01) Julián Vidal V.; Ossa A.; Julián Vidal V.; Ossa A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaPerm. Deformation of Asphaltic Mixtures in the Metropol. Area of Valle de Aburra - Antioquia, Which Are Built under IVIAS' Specifications and Valle de Aburra, Were Studied by Employing A Constitutive Model Proposed Previously. This Model Had Proved to Be Effective in Predicting Deformations of Asphaltic Mixtures in the U. Kingdom under Different Kinds of Loads; under Uniaxial and Triaxial Conditions and Temperatures at Intervals between 0C and 40C. for the Specific Case of Valle de Aburra, Temperatures Ranged between 20C and 50C and the Model Was Implemented in Order to Predict Susceptibility to Perm. Deformation. by Means of An Exp. Stud. on Mixtures, It Was Found That Their Behav. under Steady State Condition Followed the Model Modified by Cross2, Thus Mixtures Showed A Visco-Lin. and Non-Lin. Behav. at Low and High Stress Levels, Respectively. It Was Observed That under Loading and Unloading Conditions, There Is A Temp. Dependence on the Mat. Behav., Which Was Properly Predicted by Arrhenius3 under the Studied Temperatures Interval. When Modeling Mixtures Behav., It Was Found That That Their Strain Susceptibility Varied Widely Depending on the Constituent Mat., Especially on the Aggregate, in Spite of the Fact That the Mixtures Are Similar.Ítem Spherical indentation behavior of asphalt mixtures(ASCE-AMER SOC CIVIL ENGINEERS, 2007-01-01) Ossa, E.A.; Collop, A.C.; Ossa, E.A.; Collop, A.C.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaThe spherical indentation response of a dense bitumen macadam asphalt mixture with two different volume fractions of bitumen binder is investigated both experimentally and via an analytical model. The model for the indentation of bitumen developed by Ossa et al. in 2005, was used to study the spherical indentation behavior of the mixtures with good agreement when compared to experimental results. An extensive experimental study of the monotonic and recovery spherical indentation behavior is reported for a range of temperatures. In line with the predictions of the model, the monotonic indentation response of the mixtures exhibits a power-law dependence on the indentation force. The model is also successful in capturing the indentation recovery behavior of the mixtures. A comparison of the material parameters obtained from uniaxial compression and indentation tests showed that indentation tests can be used in an easy and reliable way to obtain the fundamental asphalt parameters. Further, parameters found from indentation tests implicitly account for the confining conditions generated by the aggregate particles below the indenter. © 2007 ASCE.Ítem Thermo-oxidative aging of bitumen(Taylor and Francis Ltd., 2018-07-03) Gamarra, A.; Ossa, E.A.; Gamarra, A.; Ossa, E.A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaThermo-oxidative bitumen ageing has been commonly recognised as the main cause of asphalt cracking. The effect of thermo-oxidative ageing level on bitumen has been studied in this work by means of a simple and effective mechanical stirring process. Physical characteristics of the material as Softening Point, Penetration and Viscosity were measured to samples with different ageing conditions. Chemical changes in the material were evaluated by means of SARA fractioning to measure the effect of ageing on the fundamental components of bitumen, and Infrared Spectroscopy in order to study the changes found on the oxidation-related compounds of the material. Microstructural changes on the material were evaluated using atomic force microscopy (AFM) finding that the ageing process on bitumen increases the number and size of the phases related to asphaltenes and resins, and decreases the amount of phases related to aromatics. The changes in chemical and physical characteristics of bitumen were found to be strongly dependent on the carbonyl formation. An extension to a previously proposed oxidation kinetics model was used to predict the fast rate (transient) and constant rate (steady-state) oxidation behaviour of bitumen and its relation to physical properties. The thermo-oxidative changes suffered by bitumen are associated with increasing hardening of the material, making it susceptible to cracking when in contact with aggregate as thin films in flexible pavements. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Ítem Viabilidad de la implementación del asfalto caucho a partir de un diseño de mezcla de MPI en PROCOPAL S.A.(Universidad EAFIT, 2017) Díez Trujillo, Juan Pablo; Vásquez Vásquez, Juan Simón; Sánchez Zúñiga, Marcos Antonio