Desarrollo de un tratamiento de estabilización sobre los residuos de fuel del Prestige : posibilidades de almacenamiento definitivo del resíduo estabilizado y potencial uso como material de construcción

[Resumen] El Prestige vertió 63.000 t de fuel pesado frente a las costas gallegas en una de las peores ma-reas negras acaecidas en Europa. Las tareas de recuperación de residuos se realizaron en el mar y también en la costa obteniendo residuos muy diferentes. En el mar se recuperaba una emul-sión de agua y fuel, sin embargo en el litoral, dada la extensión del vertido y la necesidad de trabajo manual, el residuo producido era una mezcla de fuel, agua, arena, rocas, bolsas plásticas, herramientas de limpieza, etc. De este modo, aunque sólo se recuperaron 43.000 t de fuel la can-tidad de residuos generada fue muy superior, 170.000 t. El objetivo de esta investigación es encontrar soluciones para el tratamiento y gestión del residuo generado por el vertido del Prestige. Es un residuo muy heterogéneo y presenta además una textura líquido-viscosa. Esta última propiedad imposibilita el vertido directo por prohibi-ción expresa de la Directiva 1999/31 de vertederos. Las técnicas de tratamiento de un residuo tan heterogéneo son limitadas, además existían unas pruebas satisfactorias de aplicación de una técnica de estabilización/solidificación con cal viva. Por estas razones se planteó el tratamiento de los residuos mediante estabilización, en este sentido se ha desarrollado una metodología de estabilización que utiliza no sólo cal viva, sino también serrín de granito, un subproducto del corte de piedra. Gracias a la sustitución de parte de la cal por serrín de granito se mejora el mezclado y se abaratan mucho los costes de estabili-zación. La proporción de mezcla más adecuada es una de 30 % de residuo de fuel, 35 % de cal viva y 35 % serrín de granito. Con estas proporciones se obtiene un residuo sólido de textura pulverulenta que puede ser fácilmente manipulado. Tras el proceso de estabilización el residuo es sólido y presenta buenas características geo-técnicas y además, en virtud de los ensayos de lixiviación, recibiría una clasificación de no peli-groso según la legislación vigente. Por tanto, sería posible construir un vertedero para el depósito definitivo del residuo estabilizado. Se ha considerado también la utilización de los residuos estabilizados como áridos para morteros de cemento, no por que el fuel mejore sus propiedades, sino como una vía para el reci-claje del residuo. Se ha conseguido fabricar morteros que emplean residuo estabilizado como árido, alcanzando un 12 % de fuel en masa. La inclusión del fuel empeora las resistencias aun-que mejora la resistencia al hielo-deshielo. La calidad de los morteros con fuel es aceptable para muchas aplicaciones, y esto combinado con una buena resistencia a la helada haría posible su utilización en elementos prefabricados no estructurales destinados a tráficos ligeros, tales como adoquines prefabricado

Mussel shell mortars durability: Study of aggregate replacement limit

[Abstract]: The knowledge acquired through previous experimental phases with coating mortars with mussel shell aggregates led to conclude that irregular, flaky and hydrophobic particles of the mussel shell and the organic matter content introduce entrapped air and entrained air in the mixes. This phenomenon causes different and opposite effects on the main properties of mortars, which are in some way positive and negative (for durability), consequently, their durability cannot be easily predicted. The present work pretends to analyse the results of different durability tests, such as water vapour permeability, adhesive strength, and weathering cycles to recommend the maximum percentage of mussel shell sand used in coating mortars that guarantee the required lifespan. After an in-depth literature review, it can be said that it is not easy to predict the durability of mortars using mussel shell aggregates. This question has been hardly analysed in the existing literature and the maximum substitution percentage of conventional aggregate that can be replaced is not clear. This work aims to answer this issue by analysing different properties: water vapour permeability, adhesive strength, and weathering cycles. Mussel shell content improves the water vapour permeability of both air lime and cement mortars but worsens the adhesive strength and weathering cycle behaviour. For most applications, 25 % of mussel shell aggregate can be employed, but for some applications, 50 % or even 75 % of mussel shell aggregate is feasible and will avoid the undesirable landfilling of this waste.This work has been developed within the framework of the project "Valorización de las conchas de bivalvos gallegos en el ámbito de la construcción" (Valorisation of Galician bivalve shell in the construction sector; Code 00064742/ITC-20133094), funded by CDTI (Centro para el Desarrollo Tecnológico e Industrial) under the FEDER-Innterconecta Program, and co-financed with European Union ERDF funds

Influence of the Mixing Procedure on the Fresh State Behaviour of Recycled Mortars

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The effect of two different mixing protocols on the fresh-state behaviour of self-compacting mortars with and without recycled sand was compared. For this purpose, the mortar mixes were designed considering three solid volume fractions, while maintaining the water to cement ratio and superplasticiser dosage constant. The results conclude that the inclusion of recycled sand harmfully affects the rheological behaviour of the mortars and this effect can be mitigated using mixing protocols with longer mixing times and delayed admixture addition times. Finally, a rheograph was developed to explain the expectable changes in a conventional mix when recycled sand is incorporated, the solid volume fraction is varied and changes are applied to the mixing procedure

Comparison data between hybrid and galvanic anode installation in the Arousa Island Bridge

The Arousa Island Bridge, with its 1980 m is the only road access to the Arousa Island. Built in 1985, this single-cell box girder divided in 40 spans runs entirely on the sea. The deck is between 2 to 12 m above sea level, so after 25 years in a marine environment, the structure showed reinforcement corrosion, especially in piles and deck bottom. Attending to the corrosion damages, caused simply from a chloride attack, the local government decided to intervene with an ambitious repair project. This decision has been taken only after an exhaustive cost analysis to determine the feasibility of repairing the structure against the construction of a new one. In this project, the reparation was divided in three types of intervention: conventional reparation with patches, galvanic anode installation and hybrid anode installation. The objective of this division is the data collection for further repairs. The research will be explained in detail and the comparative results will be explained in depth, therefore examining the corrosion progresion and service life. Currently, after careful analysis of examining the last 6 years of data, the hybrid anode installation is the system with the better initial results. Though with the evolution of the years, the galvanic anode installation is just as effective

Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.This work was supported by the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Health (FIS; PI16/00425 and PI19/00321), Centro de Investigación Biomédica en Red Enfermedades Raras (CIBERER, 06/07/0036), IIS-FJD BioBank (PT13/0010/0012), Comunidad de Madrid (CAM, RAREGenomics Project, B2017/BMD-3721), European Regional Development Fund (FEDER), the Organización Nacional de Ciegos Españoles (ONCE), Fundación Ramón Areces, Fundación Conchita Rábago and the University Chair UAM-IIS-FJD of Genomic Medicine. Irene Perea-Romero is supported by a PhD fellowship from the predoctoral Program from ISCIII (FI17/00192). Ionut F. Iancu is supported by a grant from the Comunidad de Madrid (CAM, PEJ-2017-AI/BMD7256). Marta del Pozo-Valero is supported by a PhD grant from the Fundación Conchita Rábago. Berta Almoguera is supported by a Juan Rodes program from ISCIII (JR17/00020). Pablo Minguez is supported by a Miguel Servet program from ISCIII (CP16/00116). Marta Corton is supported by a Miguel Servet program from ISCIII (CPII17/00006). The funders played no role in study design, data collection, data analysis, manuscript preparation and/or publication decisions

Carbonation evolution of lime putty coatings with mussel shell aggregate

The carbonation process is studied from young ages up to 2 years in mortars with fine mussel shell aggregate. Mussel shell aggregate affects lime mortars due to its shape (angular and flaky) and texture (smooth), and also its microstructure consisting of 2% organic matter in the form of protein and polysaccharides (chitin). Its effect is analysed in pore structure, microstructure by SEM, carbonation by phenolphthalein, and mechanical strength by means of compressive strength and ultrasounds. Conclusions show that the use of mussel shell aggregate delays carbonation at young ages (28 days) while increasing the total carbonated area at longer ages (1 and 2 years). These two different trends can be seen in all of the properties analysed. © 2020 Elsevier Lt

Effects of mussel shell aggregates on hygric behaviour of air lime mortar at different ages

Mussel shells, composed of calcium carbonate (>95%) and organic matter, are suitable alternatives to conventional sand in mortar. In addition, the use of lime instead of cement as a binder has also been considered for sustainable construction materials as well as in restorative applications. This study aims to contribute to the knowledge of air lime mortar through the analysis of the water transport properties of air lime mortar produced with mussel shell aggregates at different ages. Four mortar groups were obtained from the reference mortar by replacing limestone sand with mussel shell sand at substitution rates of 25%, 50%, and 75%. Water absorption, capillary uptake, weight variation, and drying from the fresh state up till one and two years were determined. The organic matter content and flaky seashell shape are responsible for the main differences observed between the mussel mortars and reference mortar. These two characteristics promote transport tortuosity paths and hydrophobic behaviour leading to reduced capillary uptake and increased drying resistance index. Furthermore, they enhance water retention, which increases the carbonation rate. © 2020 Elsevier Lt

Impact of mussel shell aggregates on air lime mortars. Pore structure and carbonation

Galician “Rías”·conditions (extension, water temperature ….) enable the production of excellent quality cultured mussels. This leads Spain to be the third producer country in the world. Cannery industry (35% of the total cultured mussel production) generates 25000 tons of mussel shell waste per year. Hence, it is necessary to find a sustainable use for this material. The purpose of this work is to verify the most significant changes in the properties of air lime coating mortar when replacing limestone sand with mussel shell sand. Two different air limes have been used: non-aged hydrated commercial lime powder and 10 month-old slaked lime putty. Reference mortars and mortars with mussel shell aggregate as a substitute for limestone aggregate at different rates - 25%, 50% and 75% - have been tested. The behaviour of mortars at the age of one year from kneading has been studied. Studies show that mussel shell increases the pore volume of air lime mortar mixtures, which means a reduction in the mortar's workability and density. The poor paste-aggregate cohesion of mussel shell particles in the air lime matrix worsen the mortar mechanical strength results, which is confirmed by ultrasound test results. Carbonation at this age and hygric behaviour are properties that improve with mussel shell content. © 2019 Elsevier Lt

Design and properties of cement coating with mussel shell fine aggregate

The production of farmed mussels amounts to millions of tonnes across over 40 countries. Shell waste resulting from this production has a very significant environmental impact. In Galicia, mussel shell waste is transformed, using low impact heat treatment, into a by-product that can be used as an aggregate. This research investigates cement-coating mortars where conventional aggregate is partially replaced with mussel shell aggregate. Reference mortars and mortars with mussel shell sand replacing conventional sand at different rates: 25%, 50% and 75% have been tested. Results show the feasibility of mussel shell in cement coatings at an optimal replacement rate of 25% of the conventional aggregate. © 2019 Elsevier Lt