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Imperative to the design of new cements that bear different types of waste as additions is a parallel study of the mechanical strength and durability of the new materials to ensure their performance will be satisfactory throughout their service life. This study explored the effect of adding 10 % or 20 % granite quarry dust to cement on properties such as transport (total and capillary water absorption and electrical resistivity), dimensional stability (drying shrinkage and expansion), the alkali-silica reaction, heat of hydration and colour. No alkali-silica reaction was observed in the new materials and expansion and contraction were less intense than in conventional cement. The water absorption and capillary absorption coefficients rose less in the additioned cements than the replacement ratio, whilst their higher resistivity values afforded greater corrosion protection than found in the reference. The inclusion of this waste also prompted a rise in lightness and a decline in peak heat of hydration. The multivariate analysis of variance (MANOVA) conducted showed that the factors time and replacement ratio affected the properties significantly, whereas the combined effect of the two was statistically significant or otherwise depending on the property analysed. The findings showed that the partial replacement of cement with quarry dust is not detrimental to product durability and the recycled material qualifies as a strength class 42.5, type II/A. Adittionally, the binders bearing 20 % granite quarry dust meet the requirements to qualify as low heat cements (CEM II/A LH).

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Blending supplementary cementitious materials with portland cement is one of the current strategies for producing more eco-efficient binders by lowering the energy consumption and CO 2 emissions intrinsic to OPC manufacture. The effect of such additions on heat of hydration and energy performance is a subject of particular interest, for higher heat may reduce the service life of a concrete structure, whilst energy consumption per tonne of binder or megapascal may prove not to be energy-efficient. This paper explores the energy performance of granite sludge (GS) as an active addition to clinker and the effect of this by-product on heat of hydration and eco-efficiency. The findings show that maximum heating and total heat released are lower in the additioned than in the conventional material, with the difference widening at higher replacement ratios. Optimal energy performance is observed at ratios of 15 % to 30 % (both inclusive), with the experimental materials requiring less energy than ordinary cement per megapascal (MPa) of strength. Cements with 15 % to 30 % granite sludge are consequently eco-efficient. With 15 % GS they can be classified as ordinary, with 20 % to 30 % as low heat cements and with 35% as very low heat cements.

This study explores the effect on sulfate resistance of the use of ornamental granite industry waste as a supplementary cementitious material (at replacement ratios of 10% and 20%) in cement manufacture. The present paucity of scientific knowledge of the behaviour of these new cements when exposed to an external source of sulfates justifies the need for, and the originality of, this research. After characterising the waste chemically and mineralogically, cement paste specimens were prepared in order to determine the durability of the newly designed eco-cements using Köch–Steinegger corrosion indices. The new hydration products, which might induce microstructural, mineralogical, or morphological decay in the specimens, were also analysed by comparing the samples before and after soaking in a sodium sulfate solution for different test periods. Respect to the results, the damage to pastes bearing 10% granite sludge (GS) is the same as observed in OPC, whilst the former exhibit a higher Köch-Steinegger corrosion rate (1.61) than both OPC and OPC+20GS. Soaking the pastes in sodium sulfate induces matrix densification due to ettringite formation and gypsum precipitation in the pores. Further to those results, at an optimal replacement ratio of 10%, these alternative, eco-friendlier materials can be used in the design and construction of non-structural cement-based (mortar or concrete) members exposed to an external source of sulfate.

Cement-based materials decay with exposure to aggressive agents, a development that raises infrastructure operation and maintenance costs substantially. This paper analyses the inclusion of ultrafine construction and demolition (UC&DW) and biomass-fuelled power plant (BA) waste as pozzolanic additions to cement in pursuit of more sustainable and eco-respectful binders and assesses the durability of the end materials when exposed to seawater, chlorides (0.5 M NaCl) or sulphates (0.3 M Na2SO4). The effect of adding silica fume (SF) at a replacement ratio of 5% was also analysed. Durability was determined using the methodology proposed by Koch and Steinegger, whilst microstructural changes were monitored with mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and scanning electron microscopy (SEM) for a fuller understanding of decay processes. According to the findings, the new blended cements containing 20%UC&DW + 10%BA or 20%UC&DW + 20%BA + 5%SF resist the attack by the aggressive media studied, with a 56-d corrosion index of over 0.7. The composition of the reaction products generated with the attack is essentially the same in OPC and the SCM-bearing materials. The results show that the optimal replacement ratio for SCM is 30%.

El presente artículo es resultado de un proyecto adelantado en la línea de investigación “Formación integral,convivencia y democracia” de la Maestría en Educación de la Universidad Santo Tomás. El objetivodel proyecto apunta a la formulación de una propuesta para el desarrollo de la conciencia moral en losestudiantes de grado séptimo de básica secundaria del Colegio Agustiniano Ciudad Salitre (Bogotá).Dicho proyecto tiene como antecedente, fundamentalmente, el trabajo iniciado por Suárez y Meza entorno a la formación de la conciencia moral en la educación superior.Para favorecer este tipo de formación en los estudiantes se hace necesario establecer el grado dedesarrollo de la moralidad del sujeto, para lo cual resulta importante identificar el estadio de desarrollomoral en el cual se encuentra la población seleccionada, al igual que su tendencia hacia estadios superiores.Para ello se adopta la teoría de Lawrence Kohlberg y se aplica el cuestionario de problemassociomorales –DIT, por sus siglas en inglés– planteado por James Rest. Estos parámetros guían lapresente propuesta investigativa que tiene una proyección en el ámbito escolar, específicamente en elnivel de educación básica.