Revista de la Construcción Journal of Construction 22] Mechanical properties of mortars containing recycled ceramic as a fine aggregate replacement Propiedades mecánicas de morteros que contienen cerámica reciclada como reemplazo del árido fino Abstract We study the behavior of mortars where 0%, 10%, 20%, 30%, 50% and 100% of their original natural sand was replaced by ceramic sand in a search of potential new building materials that will help to conserve natural resources and that are environmentally friendly. In this paper, the physical properties of the sands and their derived mortars, including their compressive strength, flexural strength, and shrinkage due to base and total drying, are characterized. Our results show that the compressive and flexural strengths of the recycled mortars decrease proportionally to the amount of natural sand replacement used. A similar behavior is observed for the shrinkage due to drying in mortars with low ceramic substitutions (10%, 20% and 30%). Based on these findings, we believe that the use of mortars made with recycled sand (with substitution contents lower than 30%) could be feasible in applications where the mechanical requirements are low. Resumen A partir de la búsqueda de nuevas alternativas en el área de construcción que ayuden a la conservación de los recursos naturales y del medio ambiente, se estudia el comportamiento de morteros con sustituciones parciales de reemplazo del 0%, 10%, 20%, 30%, 50% y 100% de arena cerámica reciclada por arena natural. Se caracterizan las propiedades físicas de las arenas estudiadas, así como las propiedades mecánicas de los morteros resultantes de ellas; tales como la resistencia a la compresión, flexión y de retracción básica, por secado y total. Los resultados obtenidos indican que para la resistencia a compresión y a flexión de los morteros reciclados, éstos sufren decrementos proporcionales al remplazo de la arena natural; sin embargo, para el caso de la retracción por secado éstos reportan comportamiento similar (morteros con sustituciones bajas de 10%, 20% y 30%). En base a lo anterior, morteros con arena cerámica reciclada (con contenidos menores al 30% de reemplazo) podrían ser factibles de su utilización en aplicaciones, en las cuales los requerimientos de éstos sean bajos.

The difficult current environmental situation, caused by construction industry residues containing ceramic materials could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0, 10, 20, 30, 50 and 100%), such as: the density, the compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analysis process of the results are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness; in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content). At the end of the investigation it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the prediction equations produced could be used in cases of similar applications.

The experience achieved using the tool “Questionnaires,” available inside the Virtual Campus of an architectural engineering school in northeast Spain, is presented. “Questionnaires” is a mechanism/tool adequate and simple to evaluate the knowledge level achieved by students. This work shows and identifies the control indices of adaptation for questionnaires, such as the Facility Index, the standard deviation, the Discrimination Index, and the Discrimination Coefficient. From these parameters, educational performance is inferred, identified, and predicted. The conclusions of this work will allow the modification of deficient knowledge-evaluation practices and the identification of needs for specific groups or for students with particular requirements, thus making it feasible to apply these parameters with a guarantee of success in similar evaluation processes.

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We present a theoretical investigation of copper complexes with potential applications as sensitizers for solar cells. The density functional theory (DFT) and time-dependent DFT were utilized, using the M06 hybrid meta-GGA functional with the LANL2DZ (D95V on first row) and DZVP basis sets. This level of calculation was used to find the optimized molecular structure, the absorption spectra, the molecular orbitals energies, and the chemical reactivity parameters that arise from conceptual DFT. Solvent effects have been taken into account by an implicit approach, namely, the polarizable continuum model (PCM), using the nonequilibrium version of the IEF-PCM model.

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ResumenLa corrosión en el acero de refuerzo es un problema que disminuye la vida útil en las estructuras de concreto reforzado, además de comprometer su seguridad estructural. En los modelos disponibles para estimar el efecto mecánico de la corrosión, se supone que el acero corroído, a través de los óxidos que crecen a su alrededor, ejercen una presión sobre el concreto circundante suponiendo un problema de esfuerzos o deformaciones planas. En el presente trabajo, se modela el problema con elemento fi nito tridimensional a partir de un experimento sobre un cilindro de concreto reforzado sometido a corrosión acelerada, instrumentado para medir indirectamente la presión en la interfase acero-concreto. De los resultados obtenidos se concluye que el efecto de la longitud de acero corroído, longitud anódica, tiene un efecto signifi cativo sobre la magnitud de la presión en la interfase acero-concreto, hecho que puede ser utilizado para mejorar los modelos existentes. Descriptores