Prevention of sulfate-induced thaumasite attack: thermodynamic modelling in BaCO3-blended cement

Comunicación presentada en el International Congress on Materials and Structural Stability (CMSS 2013), celebrado en Rabat del 26 al 30 de noviembre de 2013.Thaumasite, an expansive salt, remains stable over a wide range of compositions in the CaO-SiO2-Al2O3-CaCO3-CaSO4-H2O system. Despite its slow formation, it constitutes a risk for the integrity of underground structures such as foundations and tunnels that are in contact with sulfate-containing soil or groundwater. Sulfate-resistant Portland cements, which pursuant to the existing legislation are manufactured with clinker containing 0-5 % of C3A, prevent ettringite- but not thaumasite-mediated concrete deterioration. The present study used thermodynamic modeling to explore the viability of a new type of BaCO3-blended Portland cement able to resist thaumasite formation. The results of sulfate attack (44 wt% Na2SO4 solution), simulated with the GEMS geochemical code in cements with 5 or 20 % BaCO3, or 2.5, 5, 10 or 20% CaCO3 at 8 ºC, showed that less thaumasite precipitated and at higher sulfate/cement ratios in the presence than in the absence of Ba. Particularly at the higher replacement ratio, Ba proved to be able to immobilise sulfates in the medium via the precipitation of BaSO4, a highly insoluble salt, and hamper the precipitation of thaumasite. The study also showed that a higher BaCO3 content in the system hindered thaumasite formation even in the presence of greater amounts of carbonates. At 5 % BaCO3, thaumasite started to precipitate after 53 g of Na2SO4 were added per 100 g of cement, while at 20 %, the sulfate content threshold was higher, at 70 g per 100 g of cement, and smaller quantities of the salt formed.Funding from the Spanish Ministry of Education and Science (Project CONSOLIDER CSD2007-00058) and the Regional Government of Madrid (Geomaterials Programme) is gratefully acknowledged.Peer Reviewe

Resiliencias feministas frente a las Violencias Machistas en Lamu, Kenia. La Mutilación Genital Femenina

Con este proyecto se valora el grado de implementación de las reformas legislativas en materia de Violencia de Género y especialmente respecto de la práctica de la Mutilación Genital Femenina en Kenia en la actualidad y las estrategias de resiliencia propias de las mujeres indígenas frente a las Violencias Machistas con el objetivo de recuperar las voces subalternas (Spivak, 1992). Se comienza la investigación por medio de un una revisión normativa y un estudio piloto en el terreno donde se realizan distintas entrevistas en profundidad a mujeres indígenas y entrevistas semi-estructuradas a agentes clave vinculados a proyectos de cooperación en la zona y dentro del proceso institucional frente a las Violencias Machistas. Entre las conclusiones se identifica cómo la prohibición de la mutilación femenina ha traído consecuencias positivas, pero también negativas, como el aumento del riesgo para la salud de las menores a las que todavía se les práctica esta mutilaciónThis project assesses the degree of implementation of the legislative reforms on Gender Violence and especially regarding the practice of Female Genital Mutilation in Kenya today and the resilience strategies of indigenous women. with the aim of recovering the subaltern voices (Spivak, 1992). The research is started by means of a normative review and a pilot study in the field where different interviews are carried out with indigenous women and semi-structured interviews with key agents linked to cooperation project and within the institutional process to the gender violence. Among the conclusions, it is identified how the prohibition of female mutilation has brought positive, but also negative, consequences, such as the increased risk to the health of minors who are still being practiced this mutilation

Analysis of the risk factors of gender-based violence and resilence strategies of women in Lamu, Kenya

According to the World Health Organization (2018), gender-based violence is a global phenomenon that affects more than a quarter of women around the world. Despite the promulgation of a multitude of regulations against gender-based violence, it is estimated that more than 40% of women who suffer violence do not report it (ONU, 1979, 2017; Unión Africana, 2005). This study aims to identify and encourage strategies to counter gender-based violence in Indigenous women od Lamu, Kenya. In this work, we adopt the social justice perspective developed by Young (1990) to ask how the gender-based violence legislative reforms of the last few years in Kenya have affected indigenous women, what resilience strategies they have developed, and whether these strategies could be integrated into institutional actions. To this end, a field study was developed in Lamu (Kenya), where we conducted in-depth interviews with indigenous women and key agents. We concluded by establishing a relationship between the lack of female participation and the barriers that still exist in gender-based violence administration that silence and revictimize indigenous women (Maqueda, 2008). We also emphasize the importance of rejecting the passive image of women and incorporating the resilience strategies they have developed in education and work (Salvador, 2015; Piotti, 2015; Hambry, 2005).Según la Organización Mundial de la Salud (2018), la violencia de género es un fenómeno global que afecta a más de una cuarta parte de las mujeres en todo el mundo. A pesar de la promulgación de multitud de normativas contra la violencia de género, se estima que más del 40% de las mujeres que sufren violencia no la denuncia (ONU, 1979, 2017; Unión Africana, 2005). Este estudio tiene como objetivo identificar y fomentar estrategias para contrarrestar la violencia de género en las mujeres indígenas de Lamu, Kenia. En este trabajo, adoptamos la perspectiva de justicia social desarrollada por Young (1990) para preguntar cómo las reformas legislativas sobre violencia de género de los últimos años en Kenia han afectado a las mujeres indígenas, qué estrategias de resiliencia han desarrollado y si estas estrategias podrían integrarse en las acciones institucionales. Para ello, se desarrolló un estudio de campo en Lamu, donde realizamos entrevistas en profundidad con mujeres indígenas y agentes clave. Concluimos estableciendo una relación entre la falta de participación femenina y las barreras que aún existen en la gestión de la violencia de género que silencian y revictimizan a las mujeres indígenas (Maqueda, 2008). También destacamos la importancia de rechazar la imagen pasiva de las mujeres e incorporar las estrategias de resiliencia que han desarrollado en la educación y el trabajo (Salvador, 2015; Piotti, 2015; Hambry, 2005)

Autonomías departamentales en Bolivia : hacia la consolidacion de un sistema político multinivel

Artículo originalLas elecciones departamentales y municipales de marzo del 2015 en Bolivia revelan, por una parte, la incertidumbre en las reglas de juego y, por el otro, la relativa autonomía en la configuración de las fuerzas y los sistemas políticos en los distintos niveles de la organización política territorial sub-nacional. Esto se dio en el marco de un sistema de partidos nacional fuertemente marcado por la expansión y presencia predominante de un partido político: el Movimiento al Socialismo. Las incongruencias de los resultados de las elecciones sub nacionales de 2015 respecto a las elecciones nacionales de octubre de 2014, quiebran la aparente faz monolítica del comportamiento electoral que se expresa a nivel nacional a favor del actual presidente y del partido gobernante. No obstante, las opciones políticas alternativas están débilmente articuladas y muestran una limitada capacidad de irradiación territorial y presencia multinivel en la geografía política bolivian

Thermodynamic modeling of sulfate-resistant cements with addition of barium compounds

Comunicación presentada en el International Congress Science and Technology for the Conservation of Cultural Heritage (TechnoHeritage), celebrado en Santiago de compostela del 2 al 5 de octubre de 2012.Sulfate attack by ground waters, soils, etc. is one of the threats to the built heritage in concrete. This study validated through thermodynamic modeling with GEMS geochemical code a new sulfate-resistant formulation based on the addition of BaCO3 and BaO to ordinary Portland cement (OPC), which could be used to replace weathered concrete. The thermodynamic calculations pointed out that Ba ions were able to form an insoluble salt, barite (BaSO4) with the dissolved sulfate which inhibited the formation of ettringite, the latter oc- curred when the concentrations of BaCO3 and BaO were ≥ 6 and ≥ 4 wt.%, respectively. The results of a simulated sulfate a ttack revealed that ettringite precipitated upon ingression of ≥46 ml of a Na2SO4 solution (44 wt.%) in OPC blends with 20 wt.% of BaCO3; whereas with 20 wt.% of BaO, the sulfate that precipitated besides ba rite was monosulfoaluminate when sulfate solution was ≥40 ml (tested up to 52 ml).Funding from the Spanish Ministry of Education and Science (Project CONSOLIDER CSD2007-00058) and the Regional Government of Madrid (Geomaterials Programme) is gratefully acknowledged.Peer Reviewe

Forgetting “Novel” but Not “Dragon”: The Role of Age of Acquisition on Intentional and Incidental Forgetting

Two experiments studied how the age at which words are acquired (Age of Acquisition, AoA) modulates forgetting. Experiment 1 employed the retrieval-practice paradigm to test the effect of AoA on the incidental forgetting that emerges after solving competition during retrieval (i.e., retrieval-induced forgetting, RIF). Standard RIF appeared with late-acquired words, but this effect disappeared with early-acquired words. Experiment 2 evaluated the effect of AoA on intentional forgetting by employing the list-method directed forgetting paradigm. Results showed a standard directed forgetting effect only when the to-be-forgotten words were late-acquired words. These findings point to the prominent role of AoA in forgetting processes.This research was supported by grants from the Spanish Ministry of Economy and Competitiveness (http://www.mineco.gob.es/portal/site/mineco/?lang_choosen=en) to AM (PSI2013-46033-P), TB (PSI2012-33625), and CJG-A (PSI2011-25797), and from the Ministry of Science (http://www.mineco.gob.es/portal/site/mineco/?lang_choosen=en) (EDU2008-01111) and the Andalusian Government (http://www.juntadeandalucia.es/) (P12-CTS-2369) to TB

Developing new sulfate-resistant cements: a BaCO3 approach

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1OPC mortar and concretes can be attacked by sulphate solutions giving rise to different decaying processes, related with the formation of ettringite, gypsum, thaumasite etc. At present deterioration due to ettringite formation is avoided by limiting aluminate phase in clinker Portland, however it does not prevent other forms of sulphate attack. Barium carbonate has been used in several fields to eliminate sulphate ion from solutions due to it reacts with them and produces a very insoluble salt, BaSO4. There are in the literature studies demonstrating that ettringite as well as gypsum decompose in the presence of barium carbonate. Studies on the hydration rate of synthetic C3A in the presence of varying percentages of gypsum, BaCO3 or gypsum+BaCO3 revealed that BaCO3 neither regulated the speedy reaction of C3A with water nor reacted with the aluminate. Blends of gypsum plus BaCO3 proved able to regulate C3A hydration. The objective of this paper was to know the behavior of mortars elaborated with optimized mixes of clinker-gypsum-BaCO3 in 4.4 wt% Na2SO4 solution. For this four cements were elaborated by mix of: a) clinker M with 5% of gypsum; b) Clinker M with 3% of gypsum and 15% of BaCO3; c) clinker V and 7 wt% of gypsum; d) clinker V plus 3wt% of gypsum and 15% of BaCO3. Studies on durability were performed on mortar prisms of 10x10x60 mm size, with cement/sand ratio = 1/3 and water/cement ratio = 0.5. Cement Mortar prisms remained submerged under water and under sodium sulfate solution for one year. Samples were extracted from solution after 1,3,5,7 and 12 months and then mechanically tested. XRD and SEM/EDX were performed on the said samples. The compressive but mainly flexural strengths of mortars a), decreased from 5 months in contact with sulphate solution while in the mortars b) strengths remain unaltered after 12 months. Mechanical strengths of mortars c), decreased from 3 months in contact with sulphate solution and were completely destroyed after 12 months of exposition. BaCO3 fails as protector from sulphate attack in d) mortars which were cracked after one year of sulphate exposition. Correlations between mineralogical composition and microstructural changes in mortars along time of test were established.Peer Reviewe

La violencia contra niños, niñas y adolescentes, la línea entre el abuso y la disciplina

Esta investigación se centra en averiguar la manera en que padres, niños y líderes comprenden y conceptualizan la violencia. El artículo explora cómo se comunican las familias, las habilidades de los padres y la influencia de los líderes comunitarios. El proyecto se realizó en la localidad de Pelileo, Ecuador, considerada área rural, con una muestra de (n = 260) entre los que se encontraban 59 líderes comunitarios, 110 niños y adolescentes y 101 padres. Los individuos pertenecían a las poblaciones de Pelileo, Bolívar, Huambaló y Cotaló, pequeños pueblos rurales que pertenecen al estado de Tunguahua, Ecuador. Para obtener datos se realizó una investigación cuantitativa utilizando encuestas para cada grupo. La investigación siguió las normas y principios de la Unidad de Investigación de la Universidad Técnica Ambato. Los resultados confirmaron la presencia de abuso físico, emocional y sexual contra niños en esta área rural donde los actores sociales solicitaron un componente de educación en las áreas de habilidades parentales y comprensión de la violencia. Como conclusiones de esta investigación se dedujo que era necesaria la cooperación con unidades gubernamentales, como el Departamento de Educación, la Junta Cantonal y la Universidad, para ofrecer el componente educativo solicitado por los actores sociales que formaron parte del proceso investigativo

Chemistry of the interaction between an alkoxysilane-based impregnation treatment and cementitious phases

Chemical compatibility with a wide range of materials is among the features that has driven the use of alkoxysilanes as consolidants in built structures. Such compatibility is particularly important in cementitious materials where the reaction with portlandite may generate C-S-H gel, one of the main hydration phases of OPC. The cementitious matrix is a complex system, however, and the reaction of its many phases with alkoxysilanes, while poorly understood, may determine treatment efficacy. This article describes a detailed study of the individual interactions between an oligomeric alkoxysilane-based impregnation treatment previously shown to interact with the portlandite present in cement paste and the cementitious phases generated in ordinary portland cement hydration. The findings show that both portlandite and C-S-H gel interact with the silicon oligomers in the hydrolysed impregnation treatment to generate a C-S-H gel (in the case of portlandite) and a rise in C-S-H gel mean chain length (MCL). Ettringite is also altered in the presence of alkoxysilanes, transforming to gypsum and AH(3). Its transformation generates a tetrahedral aluminium that is taken up into a high silicon gel sourced from the treatment to form an amorphous aluminosilicate gel. Monocarboaluminate and katoite also partially decompose in the interaction with the product, whereas gibbsite remains unaffected