Recycling coal bottom ash in construction materials: Technical specifications of bottom ash-based sound absorbing porous concrete applied in highway noise barriers

Tesis descargada de TESEOAs industrial waste continue to accumulate, they are becoming a major problem for the environment as well as for public health. In addition, European and Spanish waste legislations are promoting the recycling of industrial waste, following the waste hierarchy, instead of landfill disposal. On the other hand, another environmental problem which is becoming an increasingly significant concern because of its negative impact on human health is noise pollution. The main scope of the thesis research has been to study the recycling opportunities of coal bottom ash from Spanish coal power stations in construction materials. The objective was focused on developing a material with high content of coal bottom ash which comprises the properties required for the specific applications. The argumentative line followed in the development of the present work started from the idea of recycling Spanish coal bottom ash as a majority constituent in construction materials for specific applications, such as Portland cement replacement, coarse aggregates replacement in concrete for fire resistance panels, as part of ceramic materials and bricks, and coarse aggregates replacement in porous concrete production with sound absorbing properties. From the results obtained, bottom ash-based porous concrete for sound absorbing applications has been deeply analysed, enhancing the properties of the final product and describing the technical requirements that could validate its use in highway noise barriers at industrial scale. Besides that, durability and environmental properties have been analysed in order to study the impact of the coal bottom ash-based product on the environment and human health. Finally, in order to completely analyse the use of coal bottom ash as part of porous concrete for its application as sound absorbing porous material in road traffic noise reducing devices, it has been developed a methodology which accurately predicts the acoustic behaviour of the material without having to manufacture large panels and testing them in a reverberation room at an approved laboratory. The objectives pursued have been developed from laboratory to semi-industrial scale, which enables to extrapolate the results ensuring the use of bottom ash-based sound absorbing products in road traffic noise reducing devices

Reciclado de residuos cerámicos en materiales absorbentes acústicos

The scope of this investigation is to develop a material mainly composed (80% w/w) of ceramic wastes that can be applied in the manufacture of road traffic noise reducing devices. The characterization of the product has been carried out attending to its acoustic, physical and mechanical properties, by measuring the sound absorption coefficient at normal incidence, the open void ratio, density and compressive strength. Since the sound absorbing behavior of a porous material is related to the size of the pores and the thickness of the specimen tested, the influence of the particle grain size of the ceramic waste and the thickness of the samples tested on the properties of the final product has been analyzed. The results obtained have been compared to a porous concrete made of crushed granite aggregate as a reference commercial material traditionally used in similar applications. Compositions with coarse particles showed greater sound absorption properties than compositions made with finer particles, besides presenting better sound absorption behavior than the reference porous concrete. Therefore, a ceramic waste-based porous concrete can be potentially recycled in the highway noise barriers field.El objetivo de este trabajo es desarrollar un material absorbente acústico compuesto fundamentalmente por residuos cerámicos (80% p) que se pueda utilizar en la fabricación de dispositivos reductores de ruido de carretera. La caracterización del producto se ha llevado a cabo atendiendo a sus propiedades acústicas, físicas y mecánicas, determinando el coeficiente de absorción acústica a incidencia normal, porosidad abierta, densidad y resistencia a compresión. La absorción acústica de un material poroso está fuertemente determinada por el tamaño de poro y por la longitud dela probeta sometida a ensayo. De este modo, se ha analizado la influencia del tamaño de partícula del residuo cerámico y del espesor de las muestras estudiadas en las propiedades del producto final. Los resultados obtenidos se han comparado con los obtenidos para un hormigón poroso elaborado con árido grueso, que se ha tomado como producto de referencia tradicionalmente empleado en este tipo de aplicaciones. Las composiciones elaboradas con el residuo de mayor tamaño de partícula han mostrado mayor absorción acústica, incluso mayor que las del hormigón poroso comercial. Por tanto, un hormigón poroso elaborado con residuos cerámicos puede ser potencialmente empleado como material en la fabricación de barreras acústicas de carretera

Fly ash based geopolymeric foams using silica fume as pore generation agent. Physical, mechanical and acoustic properties

Authors would like acknowledge the help received by CITIUS (General Research Services) from University of Seville, especially the XRD laboratory.The aim of this work is the development of a porous geopolymeric foam with sound absorbing properties using silica fume as the pore generation agent. The samples were manufactured using a coal combustion fly ash as source material for the geopolymerization reaction, an alkaline solution as activating solution and silica fume as pore forming agent. Three parameters were studied: silica fume proportion (0, 20 and 40 wt%), activating solution (potassium silicate and potassium hydroxide) and setting temperature (40 and 70 °C). Once the samples were prepared, the experimental study of the most important physical, mechanical and acoustic features were carried out. The increase in the proportion of silica fume in the mixture and setting temperature produced a reduction in setting time and a raise of open void porosity, reducing the compressive strength at 28 days up to a half but increasing the sound absorption. The influence of activating solution in open porosity and sound absorbing properties was not very important

Recycling by-products from coal-fired power stations into different construction materials

The present investigation aims to analyse alternative uses of bottom ash and fly ash as part of construction materials for different applications: bottom ashbased ceramic bricks, pozzolanic material in the cement production, waste stabilisation/solidification of an electric arc furnace dust using ash-based geopolymers, and ashbased geopolymers used as hydraulic road binders. Different replacements of natural materials by different fly and/or bottom ashes have been studied in all the cases. This study has analysed various parameters influencing the manufacturing process, with the aim of reducing the energy consumption of these processes, as they have been, for example, the firing temperature of bricks and grind size of bottom ashes in cements. All materials are manufactured in a simple and economical way, in order not to increase the cost of the products, and the final products have been evaluated according to different European standards used in these applications, in order to assess their possible, actual technical feasibility. The results obtained in this study show that even higher ratios of replacement ([40 %) of ashes have properties similar to those commonly used

A porous geopolymer based on aluminum-waste with acoustic properties

Paval, a solid waste stream from the aluminum industry, is used as a pore generation agent in geopolymers. Paval was mixed with coal combustion fly ash, as a geopolymeric precursor, and activated with alkaline solution with the aim of obtaining porous geopolymers to be used as noise barriers. Both geopolymeric and pore generation reactions happen simultaneously. Aluminum from Paval can react with water and OH from the geopolymerization activating solution, producing hydrogen. The hydrogen gas released generates a highly porous material. The influence of the fly ash-paval proportion and the setting temperature on open porosity, compressive strength and noise-absorbing properties were evaluated. To better understand these influences, the setting time, volume expansion and mineral composition were also studied. The obtained results showed that a higher Paval content (fly ash-Paval ratio 50:50) and setting temperature (70 C) produced a lower setting time and higher volume expansion, increasing the open porosity and improving acoustic properties, but reducing the compressive strength. The material manufactured under these conditions showed similar amorphous phase content to the non-porous geopolymers made without Paval. On the other hand, the obtained materials did not raise environmental concerns in a normalised leaching test

Evaluación continua con Goodle-GMS a más de 800 alumnos en Ingeniería Química

El objetivo de esta experiencia ha sido la de establecer un sistema de evaluación continua en asignaturas con gran cantidad de alumnos de forma que no supongan un excesivo trabajo para el docente, que permita generar una retroalimentación a los alumnos rápida, de forma que estimule el trabajo de los estudiantes. La experiencia ha sido realizada simultáneamente a 859 alumnos matriculados de la asignatura Química, correspondiente a 1º de los Grados de Ingeniería de la Energía (85), Ingeniería Aeroespacial (137), Ingeniería de las Tecnologías Industriales (459) e Ingeniería Química (141), durante el segundo cuatrimestre en la Escuela Técnica Superior de Ingeniería de la Universidad de Sevilla.L'objectiu d'aquesta experiència ha estat la d'establir un sistema d'avaluació contínua en assignatures amb gran quantitat d'alumnes de manera que no suposin un excessiu treball per al docent, que permeti generar una retroalimentació als alumnes ràpida, de manera que estimuli el treball dels estudiants. L'experiència ha estat realitzada simultàniament a 859 alumnes matriculats de l'assignatura Química, corresponent a 1r dels Graus d'Enginyeria de l'Energia (85), Enginyeria Aeroespacial (137), Enginyeria de les Tecnologies Industrials (459) i Enginyeria Química (141), durant el segon quadrimestre a l'Escola Tècnica Superior d'Enginyeria de la Universitat de Sevilla. S'han plantejat 5 problemes personalitzats als alumnes, en funció del seu DNI, de manera que s'han lliurat i corregit mitjançant la plataforma Goodle-GMS.The objective of this experience has been to establish a system of continuous assessment in subjects with large numbers of students so they do not involve too much work for teachers and allow providing scope for quick feedback to the students so that stimulates the students' work. The experience was carried out simultaneously to 859 students enrolled for the course Chemistry, corresponding to first course of Energy Engineering (85), Aerospace Engineering (137) Engineering Industrial Technologies (459) and Chemical Engineering (141), during the second semester in the School of Engineering of the University of Seville

Automatic pronunciation assessment vs. automatic speech recognition: a study of conflicting conditions for L2-English

Producción CientíficaThis study addresses the issue of automatic pronunciation assessment (APA) and its contribution to the teaching of second language (L2) pronunciation. Several attempts have been made at designing such systems, and some have proven operationally successful. However, the automatic assessment of the pronunciation of short words in segmental approaches has still remained a significant challenge. Free and off-the-shelf automatic speech recognition (ASR) systems have been used in integration with other tools with the hopes of facilitating improvement in the domain of computer-assisted pronunciation training (CAPT). The use of ASR in APA stands on the premise that a word that is recognized is intelligible and well-pronounced. Our goal was to explore and test the functionality of Google ASR as the core component within a possible automatic British English pronunciation assessment system. After testing the system against standard and non-standard (foreign) pronunciations provided by participating pronunciation experts as well as non-expert native and non-native speakers of English, we found that Google ASR does not and cannot simultaneously meet two necessary conditions (here defined as intrinsic and derived) for performing as an APA system. Our study concludes with a synthetic view on the requirements of a reliable APA system

Utilization of Boiler Slag from Pulverized-Coal-Combustion Power Plants in China for Manufacturing Acoustic Materials

número del art. 5705The potential utilization of boiler slag generated in large amounts from pulverized-coalcombustion (PCC) power plants has recently drawn much attention due to the serious problems caused to ecosystems. In order to make maximal use of the boiler slag and reduce the environmental risk it poses, this study focused on manufacturing acoustic materials using boiler slag from Chinese PCC power plants. Three promising acoustic materials were successfully manufactured from up to 80% boiler slag with different grain sizes, with the addition of 20% Portland cement. The density and compressive strength of the products were inversely proportional and the sound absorption coefficient was positively proportional to the grain size of the boiler slag. The best sound absorption coefficient was obtained in products made from the coarsest fraction of the boiler slag (MS-C). Nonetheless, all the boiler-slag-based acoustic products still demonstrated compressive strength and densities comparable to those of other acoustic materials made of Spanish bottom ash or other conventional/recycled materials. The acoustic products made from the coarsest fraction (MS-C) and medium fraction (MS-M) of the boiler slag presented good noise absorption characteristics, like those of the commercial coarse porous cement that is traditionally used as an acoustic product. Furthermore, the acoustic products were characterized by very low leach ability of potentially hazardous elements. Consequently, the manufacture of acoustic materials is a very promising application for boiler slag. On the one hand, it consumes huge amounts of boiler slag that is generated in large amounts in China. On the other hand, the acoustic products can be used extensively to produce road acoustic barriers with a high sound absorption efficiency, no significant physical or mechanical limitations and no environmental implicationFoundation of China 41972179Foundation of China 41972180National Key R&D Program of China 2018YFF0215400Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) CUGCJ181

A Prospective Cohort of SARS-CoV-2-Infected Health Care Workers: Clinical Characteristics, Outcomes, and Follow-up Strategy

Background. During the coronavirus disease 2019 (COVID-19) outbreaks, health care workers (HCWs) are at a high risk of infection. Strategies to reduce in-hospital transmission between HCWs and to safely manage infected HCWs are lacking. Our aim was to describe an active strategy for the management of COVID-19 in severe acute respiratory syndrome coronavirus 2 (SARSCoV-2)-infected HCWs and investigate its outcomes. Methods. A prospective cohort study of SARS-CoV-2-infected health care workers in a tertiary teaching hospital in Barcelona, Spain, was performed. An active strategy of weekly polymerase chain reaction screening of HCWs for SARS-CoV-2 was established by the Occupational Health department. Every positive HCW was admitted to the Hospital at Home Unit with daily assessment online and in-person discretionary visits. Clinical and epidemiological data were recorded. Results. Of the 590 HCWs included in the cohort, 134 (22%) were asymptomatic at diagnosis, and 15% (89 patients) remained asymptomatic during follow-up. A third of positive cases were detected during routine screening. The most frequent symptoms were cough (68%), hyposmia/anosmia (49%), and fever (41%). Ten percent of the patients required specific treatment at home, while only 4% of the patients developed pneumonia. Seventeen patients required a visit to the outpatient clinic for further evaluation, and 6 of these (1%) required hospital admission. None of the HCWs included in this cohort required intensive care unit admission or died. Conclusions. Active screening for SARS-CoV-2 among HCWs for early diagnosis and stopping in-hospital transmission chains proved efficacious in our institution, particularly due to the high percentage of asymptomatic HCWs. Follow-up of HCWs in Hospital at Home units is safe and effective, with low rates of severe infection and readmission. Keywords. coronavirus; COVID-19; health care workers; Hospital at Home; SARS-CoV-2

CIBERER : Spanish national network for research on rare diseases: A highly productive collaborative initiative

Altres ajuts: Instituto de Salud Carlos III (ISCIII); Ministerio de Ciencia e Innovación.CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low-prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15-year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research