Thesis ESTIMACIÓN DE LA RESISTENCIA A LA FATIGA DE MEZCLA ASFÁLTICA EN CALIENTE CON 8% DE RAP MEDIANTE ENSAYO DE FLEXIÓN EN CUATRO PUNTOS
Date
2017
Authors
AVILA CARRILLO, MARCELO IGNACIO
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Abstract
En el comportamiento a fatiga de las mezclas asfálticas en caliente (MAC), se relaciona el nivel de deformación (o esfuerzo) con el número de ciclos para alcanzar una condición de falla especificada (Nf). La caracterización del comportamiento a fatiga de estas mezclas, realizado a través de las curvas de fatiga, es fundamental para poder garantizar su desempeño. El objetivo de este trabajo, es presentar los resultados de los ensayos de viga a flexión cargada en cuatro puntos, a deformación controlada, realizados sobre una mezcla con betún convencional CA-24 equivalente a una Clasificación PG 64-22, mediante método Superpave.Para esto se compararán los resultados de 3 tipos de mezclas con una granulometría consistente con una banda IV-A-12. La primera mezcla será tradicional de control, sin RAP, de la que se confeccionarán 12 probetas, con el objeto de caracterizar 4 puntos de la curva. La segunda mezcla con 8% de RAP grueso, de la cual se confeccionarán 3 probetas, necesarias para caracterizar el punto de control para 500 [µstrain]. Finalmente la tercera mezcla de control del proyecto de "Desarrollo de Materiales para Recapados Asfálticos Utilizados en la Rehabilitación de Pavimentos Deteriorados” FONDEF D09I1174. Los 4 puntos que se busca caracterizar en los ensayos de fatiga completa son para 250, 350, 500 y 600 [µstrain], que permitirá establecer la deformación necesaria para obtener el parámetro ¿6, correspondiente a la deformación para un millón de ciclos. Los resultados obtenidos serán también comparados con los resultados de los ensayos de la memoria de Nicolás Montalva Gorodesky, en la que se confeccionaron 12 probetas de una mezcla con 18% de RAP. Cabe mencionar que todas las mezclas, probetas y ensayos, de ambas memorias, fueron realizados en colaboración conjunta. La confección de las 27 probetas se realizó según el procedimiento descrito por la norma AASHTO T 321-14.Los ensayos realizados a las mezclas asfálticas en caliente elaboradas para este estudio arrojaron resultados que no alcanzaron el millón de ciclos para ninguno de los niveles de deformación ensayados, dejando imposibilitada la opción de interpolar el parámetro E6 (épsilon 6). Por otro lado los valores de N500 alcanzados son de orden de magnitud similar, por lo tanto se puede suponer que los resultados de la mezcla con 8% de RAP para fatiga completa se encontrarán en las mismas condiciones que las otras mezclas estudiadas.El RAP se define como el pavimento asfáltico que ha cumplido su vida útil, que ha sido fresado o extraído y posteriormente triturado, y sus propiedades dependen directamente de varios factores como: el tipo de mezcla asfáltica del que proviene, la metodología empleada en su extracción, la capa de pavimento que se extrajo, o bien, del proyecto que proviene, lo que puede generar heterogeneidad en el material, lo cual puede influir en la homogeneidad de la mezcla final que se desea fabricar, sobre todo cuando el RAP se emplea en altas tasas.La caracterización del comportamiento a fatiga de las nuevas mezclas asfálticas en caliente (MAC) con agregados de RAP son fundamentales para garantizar el desempeño de estas, por lo que este estudio, podrá ser utilizado como referencia y punto de comparación, en el diseño de mezclas que busquen respuesta al agrietamiento por fatiga.
The behavior of fatigue on hot mixtures asphalt (HMA), is related to the the deformation level (or stress) with the numbers of cycles to reach an specific fault condition (Nf). The Characteristics on the fatigue behavior for these mixtures, developed through the fatigue curves, is essential to guarantee its performance. The objective of this work was to study the results of the bending beam tests loaded in four points, controlled deformation, performed on a conventional CA-24 bitumen mixture equivalent to a PG Classification 64-22 using the Superpave method.In order to accomplish this, was the results of 3 types of mixtures with a granulometry consistent with a band IV-A-12 will be compared. The first mixture was a traditional mixture, which was used as control, without RAP, in this mixture 12 test pieces were prepares with the aim of identify 4 points of the curve. The second mixture was a mixture with 8% of thick RAP, which 3 test pieces were prepared to identify the control point for 500 [µstrain]. Finally, the third mixture of the project "Development of Materials Used in retreads Asphalt Pavement Rehabilitation Dilapidated" FONDEF D09I1174. The 4 points that seeks to identify in full fatigue tests are 250, 350, 500 and 600 [µstrain]. The results were also compared with those obtained in the work developed by Nicolás Montalva Gorodesky, in which 12 tests of a mixture with 18% addition of RAP. It is important to note that all mixtures, test pieces and tests of both works, had been carried out in cooperation. The 27 tests were prepared according to the procedure described by AASHTO T 321-14.In this study, the tests developed on the hot asphalt mixes produced were not reached results 1 million cycles for the deformation levels tested, making it impossible to interpolate parameter E6 (epsilon 6). On the other hand, the values of N500 were similar in terms of magnitude, so, it can concluded that the results of the mixture with 8% RAP for complete fatigue will be at the same conditions as the other studied mixtures.The RAP is defined as the asphalt pavement that has reached its lifespan, which has been milled or extracted, and then ground, its properties directly depend on several factors such as: the type of asphalt mix from which it comes, the methodology used during its extraction, the pavement layer that was extracted, or the project that comes from, which can generate heterogeneity in the material, influencing the homogeneity of the final produced blend, mainly when the RAP is used in High rates.The characteristics of the fatigue behavior of the new hot mix (HMA) with added RAP are fundamental to guarantee it´s performance. This work can be used as reference and point of comparison, on the design of mixes that tries to face the fatigue cracking problem.
The behavior of fatigue on hot mixtures asphalt (HMA), is related to the the deformation level (or stress) with the numbers of cycles to reach an specific fault condition (Nf). The Characteristics on the fatigue behavior for these mixtures, developed through the fatigue curves, is essential to guarantee its performance. The objective of this work was to study the results of the bending beam tests loaded in four points, controlled deformation, performed on a conventional CA-24 bitumen mixture equivalent to a PG Classification 64-22 using the Superpave method.In order to accomplish this, was the results of 3 types of mixtures with a granulometry consistent with a band IV-A-12 will be compared. The first mixture was a traditional mixture, which was used as control, without RAP, in this mixture 12 test pieces were prepares with the aim of identify 4 points of the curve. The second mixture was a mixture with 8% of thick RAP, which 3 test pieces were prepared to identify the control point for 500 [µstrain]. Finally, the third mixture of the project "Development of Materials Used in retreads Asphalt Pavement Rehabilitation Dilapidated" FONDEF D09I1174. The 4 points that seeks to identify in full fatigue tests are 250, 350, 500 and 600 [µstrain]. The results were also compared with those obtained in the work developed by Nicolás Montalva Gorodesky, in which 12 tests of a mixture with 18% addition of RAP. It is important to note that all mixtures, test pieces and tests of both works, had been carried out in cooperation. The 27 tests were prepared according to the procedure described by AASHTO T 321-14.In this study, the tests developed on the hot asphalt mixes produced were not reached results 1 million cycles for the deformation levels tested, making it impossible to interpolate parameter E6 (epsilon 6). On the other hand, the values of N500 were similar in terms of magnitude, so, it can concluded that the results of the mixture with 8% RAP for complete fatigue will be at the same conditions as the other studied mixtures.The RAP is defined as the asphalt pavement that has reached its lifespan, which has been milled or extracted, and then ground, its properties directly depend on several factors such as: the type of asphalt mix from which it comes, the methodology used during its extraction, the pavement layer that was extracted, or the project that comes from, which can generate heterogeneity in the material, influencing the homogeneity of the final produced blend, mainly when the RAP is used in High rates.The characteristics of the fatigue behavior of the new hot mix (HMA) with added RAP are fundamental to guarantee it´s performance. This work can be used as reference and point of comparison, on the design of mixes that tries to face the fatigue cracking problem.
Description
Catalogado desde la version PDF de la tesis.
Keywords
AGRIETAMIENTO POR FATIGA , ENSAYOS DE VIGA A FLEXION , MEZCLAS ASFALTICAS EN CALIENTE , RAP