Examinando por Materia "Bituminous materials"
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Ítem Modificación polimérica de asfaltos(Universidad EAFIT, 2012) Múnera Ossa, Juan Camilo; Ossa Henao, Edgar AlexanderÍtem 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 Triaxial deformation behavior of bituminous mixes(ASCE-AMER SOC CIVIL ENGINEERS, 2010-02-01) Ossa, E. A.; Deshpande, V. S.; Cebon, D.; Ossa, E. A.; Deshpande, V. S.; Cebon, D.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaThe triaxial compressive response of bituminous mixes with volume fractions of aggregate in the range 52 to 85% was investigated over a wide range stresses and strain rates. The types of loadings considered include triaxial monotonic constant stress and constant applied strain rate, as well as creep recovery, continuous cyclic, and stress pulse train loadings. The mixes with a "fully dense" aggregate skeleton were found to dilate under all loading conditions and the creep response of the mixes was dependent on both the deviatoric and hydrostatic stresses. By contrast, recovery was found to occur under zero applied deviatoric stresses with the recovery rate only dependent on the "recoverable strain" and independent of any superimposed hydrostatic stress. Continuous and pulse loading cyclic stress-controlled tests showed that the response of the mixes was governed by the mean applied deviatoric stress in the continuous cyclic tests while strain recovery was important in the pulse loading tests. A phenomenological constitutive model was proposed to fit the measured triaxial response of the bituminous mixes and shown to capture the measurements over all the triaxial stress states and loading time histories investigated here. Furthermore, the model was extended to capture the temperature dependence of the mixtures which is governed by the temperature dependence of the bitumen binder. © 2010 ASCE.