The purpose of this study was to verify the feasibility of using biochar from oat hulls (BO) as a potential bio-modifier to improve the physical properties of conventional asphalt binder. The BO and asphalt binder were characterized by confocal (fluorescence) laser microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Then, an asphalt binder modification procedure was established and modifications with 2.5, 5.0 and 7.5% of BO on the weight of the asphalt binder were evaluated, using a particle size < 75 µm. The physical properties of the evaluated modified asphalt binder with BO were: rotational viscosity in original and aged state, aging index, Fraass breaking point, softening point, penetration, penetration rate and storage stability. The results indicated that the BO has a porous structure, able to interact with the asphalt binder by C=O and C=C bonds. In addition, modification of the asphalt binder with BO increases the rotational viscosity related to high-temperature rutting resistance. The results obtained from the Fraass breaking point and softening point indicated that the use of BO extends the viscoelastic range of the asphalt binder. In addition, the evaluated modifications present low susceptibility to aging and good storage stability.
Permeable friction course (PFC) mixtures are a special type of hot mix asphalt (HMA) mixtures characterized by high total air voids (AV) content values to provide high permeability and noise reduction effectiveness, while high surface texture conditions can be ensured. Recent advancements in materials and HMA mixture evaluation led to increase the use of PFC mixtures over the last two decades as an alternative to improve highway safety and noise reduction. However, these developments on PFC mixtures generate the need for a comprehensive review to facilitate corresponding practical implementation. Consequently, the main objective of this paper is to provide a summary of research findings on PFC mixtures to improve the conception, design, and use of these HMA mixtures. In this context, the paper includes aspects related to advantages and limitations, volumetric properties, structural life, mixture distresses, and functionality of PFC mixtures. The aspects summarized provide a baseline for improvement of the current design and conception of PFC mixtures and offer guidelines for some future research developments.Keywords: Permeable friction course (PFC), mix design, hot mix asphalt (HMA), noise reductionpavements, drainable pavements.
RESUMEN
Las mezclas drenantes son un tipo especial de mezclas asfálticas caracterizadas por un alto contenido total de vacíos, que proporcionan alta permeabilidad y capacidad de reducción de los niveles de ruido, mientras se garantizan altos valores de textura superficial. Avances recientes en materiales y evaluación de mezclas asfálticas conllevaron al incremento del uso de mezclas drenantes en las dos últimas décadas
El objetivo de esta investigación fue evaluar el comportamiento mecánico del asfalto natural por medio de la fabricación de muestras a temperatura ambiente. En primera instancia se realizó la caracterización del material con el ensayo de extracción cuantitativa del asfalto y así conocer el contenido de asfalto presente en el material, luego se procedió a fabricar muestras con la asfaltita pura en el compactador giratorio y por último se ejecutó sobre éstas el ensayo de Resistencia a Tracción Indirecta, RTI, en estado seco y en estado húmedo, para así conocer la viabilidad de su uso en vías terciarias, sin tener que someterla a altas temperaturas de fabricación y mezclado. Como resultado principal se evidencia que las probetas fabricadas a temperatura ambiente presentan resistencias muy bajas, por lo cual es necesario probar con la adición de agregados pétreos a la misma temperatura y emulsiones asfálticas.
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