Preliminary investigation on the use of waste cork dust as filler in hot-mix asphalt

Este póster foi presentado no congreso "Cork in Science and Applications 2019. New Trends in Cork Innovation: From the Wine Industry to the New Applications" que foi organizado polo Institut Catalá del Suro e que tivo lugar en Palafrugell (Girona) o 22 e 23 de maio de 2019.[Abstract:] The cork contains significant amounts of a biopolymer called suberin (45%). Polymers have been frequently used in the manufacture of hot-mix asphalt (HMA) to improve their properties. At the Universidade da Coruña (UDC), a preliminary investigation was carried out in which the feasibility of using waste cork dust from the manufacture of plugs, as filler in the manufacture of HMA was analyzed. Firstly, the aggregate-binder adhesion was analyzed by means of two types of tests: the boiling water test and the rolling bottle method. The performance of the cork filler was compared with the performance of conventional natural filler. In both tests it was obtained that with the cork filler, the aggregate-binder adhesion was better than with the natural filler. Secondly, a HMA type AC 22 bin S was manufactured, with a bitumen content of 3.8%. Indirect tensile test after immersion in water were conducted, in order to compare the moisture damage resistance of mixtures made with filler cork and natural filler. It was concluded that the filler cork helped to slightly improve the water resistance of the mixture. Although further investigation is needed, it can be stated that the filler cork could replace the conventional natural filler in the production of HMA

Adhesion Analysis of Waste Cork Dust as Filler for Bituminous Mixtures

No libro: Wastes: Solutions, Treatments and Opportunities III: Selected Papers from the 5th International Conference Wastes 2019, September 4-6, Lisbon, Portugal (pp.1-6). CRC Press, 2020. ISBN 978-0-367-25777-4[Abstract] Suberin is a biopolymer that can be found in high amounts in natural cork. As is well known, polymers can be used as bitumen modifiers to improve the properties of bituminous mixtures. This paper describes laboratory adhesion analysis that was conducted to analyse the use of waste cork dust as a filler in hot-mix asphalt (HMA). The performance of the waste cork dust as a filler was compared with that of a typically used natural filler and with Portland cement. These three fillers were characterized by their grain size distributions, morphological studies, and X-ray fluorescence spectroscopy experiments. The adhesion between the aggregates and the binder was analysed using two adhesion tests: a “boiling water test” and using the “roll-ing bottle method”. Both tests led to the same result: the waste cork dust was a better filler than the natural filler.https://doi.org/10.1201/978042928979

Mechanical behavior of hot-mix asphalt made with recycled concrete aggregates from construction and demolition waste: a design of experiments approach

[Abstract:] The present work is a re-evaluation of previous research on the durability of hot-mix asphalt made with recycled concrete aggregates from construction and demolition waste (CDW) with a different approach. Response surface methodology (RSM) was used to conduct this study. The kind of natural aggregates (schist and calcite-dolomite), the recycled concrete aggregates percentage (0%, 20%, 40% and 60%) and the water saturation (0% and 100%) were the pertinent factors for this methodology. Indirect tensile stress (ITS) was determined in mixtures fabricated with 0%, 20%, 40% and 60% recycled concrete aggregates. According to the results, the ITS of the bituminous mixtures increases as the percentage of recycled concrete aggregate increases. This behavior is more significant when calcite-dolomite is used as a natural aggregate. Water saturation has the same influence in both natural aggregates. The indirect tensile strength ratio (ITSR) was calculated to evaluate the stripping potential. According to the Spanish specifications, the results suggest that the percentage of CDW that can be used for hot mixes is 17% when schist is used as natural aggregate and 14% for calcite-dolomite

Evaluation of the Resilient Modulus of Hot-Mix Asphalt Made With Recycled Concrete Aggregates From Construction and Demolition Waste

[Abstract] This paper reports the influence of the percentage of recycled aggregate (RCA) from construction and demolition waste (C&DW) together with the percentage of binder (L), curing time (t) and temperature (T) of the samples on the stiffness of a hot asphalt mixture. The study was carried out using the response surface methodology (RSM). The resilient modulus was chosen to estimate the stiffness of the mixture. The percentages of RCA studied were 0% (control), 5%, 10%, 20% and 30%, whilst 3.5%, 4% and 4.5% were those chosen for the binder content. Before compacting the samples, they were left into the oven to cure. Curing time, or pretreatment time, were set at 0 (control), 2 and 4 h. The samples were subjected to temperatures of 0, 10 and 20 °C. The natural aggregate is of the hornfels type. All the specimens studied showed high stiffness at low temperatures. According to this research, temperature proved to be the most influential factor on the decrease in the resilient modulus and, conversely, the percentage of recycled aggregate is not a significant factor in the range of values studied.Portugal. Fundação para a Ciência e Tecnologia; UIDB/04730/202

Comparison of Raman-scattering and Shubnikov-de Haas measurements to determine charge density in doped semiconductors

We have verified the accuracy of free-charge determinations from Raman scattering in doped semiconductors by comparing the results obtained from phonon-plasmon coupled-mode line-shape fits with the charge-density values extracted from the analysis of the Shubnikov-de Haas oscillations. The experiments were carried out on n-InP layers, and conduction band nonparabolicity was included both in the Lindhard-Mermin model used to fit the Raman spectra and in the Shubnikov-de Haas analysis. We find a very good agreement between Raman and magnetotransport results, which confirms the reliability of the charge-density determination from Raman-scattering measurements when the line-shape analysis is carried out using the Lindhard-Mermin model

Reformulación del estudio de casos en la asignatura Infraestructuras del Transporte

[Resumen] La asignatura Infraestructuras del transporte (INTR) se imparte en segundo curso del grado en Ingeniería de Obras Públicas (GIOP). Se trata de una asignatura de carácter obligatorio de 6 créditos ECTS. La principal dificultad con la que se encuentra el docente en esta asignatura es la transmisión de conceptos marcadamente técnicos a un alumnado que proviene de un primer curso con asignaturas de formación básica. En un inicio se procedió de forma tradicional. Es decir, se llevaron a cabo sesiones magistrales, resolución en pizarra de ejercicios con una gran variabilidad de casos prácticos y realización de un examen final como única medida evaluativa. Los resultados arrojaron una alta tasa de fracaso en la materia. Con el fin de reducir esta alta tasa de fracaso y mejorar el aprendizaje del alumnado, se optó por limitar los casos prácticos objeto de examen. Esto no debe entenderse, ni mucho menos, como una devaluación en el programa, sino una concreción de los mismos en menos ejemplos. Como complemento de ello, el docente explicaba someramente otro caso que, aunque parecido, tenía las suficientes particularidades como para constituir un ejemplo totalmente diferente. Este caso debería ser desarrollado íntegramente y en profundidad por el alumnado mediante la realización de una práctica individualizada que contaba para la evaluación de la materia. Como resultado de este nuevo marco, el número de estudiantes que superaron la asignatura ascendió en un 24 % aproximadament

Uso de prácticas reales y virtuales para el uso de cuestionarios conceptuales en la Física Aplicada

[Resumen] Es bastante común, en asignaturas como Física observar una falta de ligazón entre el fenómeno real observado y el concepto adquirido en las clases teóricas o de pizarra. Esto hace que el alumno tenga una brecha, muchas veces insalvable, que le dificulta enormemente no solo la superación de la materia, sino también la adquisición de nuevos conceptos. Además, las ciencias experimentales adolecen de horas de prácticas en el bachillerato. Teniendo en cuenta tales antecedentes, los docentes que firmamos el presente trabajo –todos ellos pertenecientes a la ETSI de Caminos, Canales y Puertos– hemos intentado desarrollar una metodología que aúne la parte conceptual de la materia con determinadas prácticas, tanto virtuales como reales, para alumnos de primer curso de Física Aplicada de nuestras titulaciones. En el presente trabajo, que es parte de otro mucho más amplio, los autores proponen una estrategia de enseñanza-aprendizaje mediante prácticas de banco de laboratorio y virtuales. La metodología seguida fue la siguiente: en primer lugar, se procedió a un análisis de pruebas docentes para la identificación de los apartados peor calificados. Una vez delimitado el marco de actuación, se procedió a un rediseño de las prácticas de laboratorio y su metodología. Así, antes de su realización se realizó una evaluación inicial para constatar el grado de conocimiento previo que el/la alumno/a poseía. Seguidamente se llevó a cabo el trabajo experimental que consistió en una práctica en banco de Laboratorio (Práctica Real) y otra mediante simulación de ordenador (Práctica Virtual). Entre ambas, se iban introduciendo algunos conceptos básicos sobre el fenómeno estudiado. Una vez finalizadas, se realizó otro cuestionario para poder analizar el resultado. El porcentaje de incremento de respuestas válidas entre ambos cuestionarios fue de alrededor del 20%. Algunas preguntas presentaban un mayor porcentaje de fallos, lo que nos dio pie a incidir sobre ellas de un modo más concreto en el aula

Structural basis for inhibition of the histone chaperone activity of SET/TAF-Iß by cytochrome c

Chromatin is pivotal for regulation of the DNA damage process insofar as it influences access to DNA and serves as a DNA repair docking site. Recent works identify histone chaperones as key re- gulators of damaged chromatin’s transcriptional activity. However, understanding how chaperones are modulated during DNA damage response is still challenging. This study reveals that the histone chap- erone SET/TAF-Iß interacts with cytochrome c following DNA damage. Specifically, cytochrome c is shown to be translocated into cell nuclei upon induction of DNA damage, but not upon stimulation of the death receptor or stress-induced pathways. Cytochrome c was found to competitively hinder binding of SET/TAF-Iß to core histones, thereby locking its histone-binding domains and inhibiting its nucle- osome assembly activity. In addition, we have used NMR spectros- copy, calorimetry, mutagenesis, and molecular docking to provide an insight into the structural features of the formation of the complex between cytochrome c and SET/TAF-Iß. Overall, these findings estab- lish a framework for understanding the molecular basis of cyto- chrome c-mediated blocking of SET/TAF-Iß, which subsequently may facilitate the development of new drugs to silence the oncogenic effect of SET/TAF-Iß’s histone chaperone activity

Late-time cosmology in (phantom) scalar-tensor theory: dark energy and the cosmic speed-up

We consider late-time cosmology in a (phantom) scalar-tensor theory with an exponential potential, as a dark energy model with equation of state parameter close to -1 (a bit above or below this value). Scalar (and also other kinds of) matter can be easily taken into account. An exact spatially-flat FRW cosmology is constructed for such theory, which admits (eternal or transient) acceleration phases for the current universe, in correspondence with observational results. Some remarks on the possible origin of the phantom, starting from a more fundamental theory, are also made. It is shown that quantum gravity effects may prevent (or, at least, delay or soften) the cosmic doomsday catastrophe associated with the phantom, i.e. the otherwise unavoidable finite-time future singularity (Big Rip). A novel dark energy model (higher-derivative scalar-tensor theory) is introduced and it is shown to admit an effective phantom/quintessence description with a transient acceleration phase. In this case, gravity favors that an initially insignificant portion of dark energy becomes dominant over the standard matter/radiation components in the evolution process.Comment: LaTeX file, 48 pages, discussion of Big Rip is enlarged, a reference is adde