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[en] The adsorptive removal of total dissolved solids by activated coal using response surface methodology was investigated. A four-variable central composite experimental design was applied to correlate the adsorption variables (effluent pH, adsorbent dosage, contact time, and adsorption temperature). The adsorption variables were optimized based on the removal of total dissolved solids from fibre cement industry effluent. Three-dimensional surface plots were generated to estimate the effect of the combinations of the independent variables on the adsorption efficiency. The results of the model validation gave experimental yield 96.2%, predicted yield 96.5% obtained at effluent pH 6.27, adsorbent dosage 27.60 mg L−1, contact time 48.00 min, and adsorption temperature of 31.00 °C. The good agreement found between observed and predicted values supports the suitability of the applied model to predict the adsorption treatment.
[en] Industrial by-products generated in the steel manufacturing are successfully used as raw materials in the production of construction materials. However, steel slags, due to their nature and composition, can cause undesirable side-effects in mortars and concretes. The reactive components of LFS and EAFS can affect the stability of the cement matrix. This situation may be prevented by an adequate pre-treatment of slag stabilization and a study of the possible reactions within its mineralogical components, to ensure the stability of the slag over time. In this work, an experimental process is shown to evaluate the behaviour of LFS under adverse environmental conditions when used as aggregates in the manufacture of cement mortars for masonry, such as the presence of humidity, high temperatures (80°C) and possible alkali-silica and alkali-silicate reactions. The results show an acceptable behaviour under normal environmental conditions (20°C). However, the formation crystalline acicular structures were observed under high temperatures (80°C) and in the presence of humidity, which degraded the internal structure of the mortars manufactured with LFS.
[es]Los subproductos industriales producidos en la fabricación de acero están siendo utilizados con éxito como materias primas en la producción de materiales de construcción. Sin embargo, las escorias de acero, debido a su naturaleza y composición, pueden causar efectos secundarios indeseables en morteros y hormigones. No obstante, las escorias de acería pueden causar efectos secundarios no deseados en los morteros y hormigones. Los componentes reactivos de las LFS y EAFS pueden afectar a la estabilidad de la matriz de cemento. Esta situación se puede prevenir mediante un adecuado tratamiento previo de estabilización de la escoria y de un estudio de las posibles reacciones de sus componentes mineralógicos, para asegurar su estabilidad en el tiempo. En este trabajo se muestra un proceso experimental para valorar el comportamiento de las escorias blancas de Horno Cuchara LFS cuando se utilizan como áridos en la fabricación de morteros de cemento para albañilería, comprobando su comportamiento en condiciones ambientales adversas, tales como la presencia de humedad, altas temperaturas (80°C) y las posibles reacciones álcali-sílice y álcali-silicato, con el objetivo de determinar su viabilidad en el diseño de morteros. Los resultados muestran un comportamiento adecuado en condiciones de ambientales normales (20°C). Sin embargo, a altas temperaturas (80°C) y en presencia de humedad se desarrollan estructuras cristalinas aciculares que provocan la rotura de la estructura interna de los morteros fabricados con LFS.
[en] Cement is the basic material for constructions which is made from a mixture of elements that are found in natural materials such as limestone, marl and/or clay. Cement manufacturing is an energy and resource intensive process with both local and global environmental, health and safety impacts. Because of these impacts, ensuring healthy and safe working conditions for employees is one of the most significant issues for the cement industry. In this review, cement manufacturing process was clarified briefly and potential hazards and their risks in cement industry were investigated.
[en] Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement.
[es]Se estudiaron residuos cerámicos de demolición (DCWs) a fin de determinar su potencial uso como materiales cementicios suplementarios en cementos mezcla (PBC). Para este propósito, se investigaron tres residuos cerámicos. Luego de la caracterización de los materiales a utilizar, se analizó el efecto del reemplazo por residuos cerámico (8, 24 y 40% en peso). Se estudió la actividad puzolánica, el progreso de la hidratación, la trabajabilidad y la resistencia a compresión a 2, 7 y 28 días. Los resultados mostraron que los residuos molidos se comportaron como fillers a edades tempranas, pero con el progreso de la hidratación, la actividad puzolánica de los residuos cerámicos contribuye a los requerimientos de resistencia.
[en] The influence of secondary fuels components used for Portland clinker production on emission value of heavy metals is presented in this paper. Analyses and studies of hazardous substances emission (heavy metals) from cements and concretes were conducted according to standards developed by Technical Committee CEN TC 351. The contents of following heavy metals were analyzed: Cr, Zn, Cd, Pb, Co, Ni, Mn, Cu, Sr, Ba and P in secondary fuels used by cement industry in Poland for Portland clinker production. Total heavy metal contents in cements and their leaching from cements CEM I were studied. Leaching of heavy metals from CEM I-based concretes to environment was also determined. Obtained tests results allow to conclude that changes in technology of cement clinker production leading to the usage of waste materials and secondary fuels does not cause an increase in heavy metals emission in level, which requires qualifying cement as material, which has to be regularly controlled for harmfulness on man and natural environment. (paper)
[en] This study investigates the magnesium sulphate resistance of chemically activated phosphorus slag-based composite cement (CAPSCC). Enough mortar specimens were prepared from phosphorus slag (80 wt.%), type II Portland cement (14 wt.%), and compound chemical activator (6 wt.%) and were exposed to 5% magnesium sulphate solution after being cured. Mortar specimens of both type II and V Portland cements (PC2 and PC5) were also prepared and used for comparison purpose. According to the test results, after 12 months of exposure, PC2, PC5 and CAPSCC exhibited 43.5, 35.2 and 25.2% reduction in compressive strength, 0.136, 0.110, and 0.026% expansion in length, and 0.91, 2.2, and 1.78% change in weight, respectively. Complementary studies by X-ray diffractometry and scanning electron microscopy revealed that CAPSCC has a very low potential for the formation of sulphate attack products, especially ettringite. The results confirm a high magnesium sulphate resistance for CAPSCC compared to PC2 and PC5.
[es]Este trabajo aborda el estudio de la resistencia al sulfato de magnesio de un cemento compuesto con base de escoria de fósforo activada químicamente (CAPSCC). Se prepararon muestras de mortero a partir de escoria de fósforo (80% en peso), cemento Portland tipo II (14% en peso) y activador químico (6% en peso) y tras el curado, se expusieron a una solución de sulfato de magnesio al 5%. También se prepararon morteros de cementos Portland de tipo II y V (PC2 y PC5) que se usaron con fines comparativos. De acuerdo a los resultados obtenidos, después de 12 meses de exposición, PC2, PC5 y CAPSCC mostraron un 43.5, 35.2 y 25.2% de reducción en la resistencia a la compresión, 0.136, 0.110, y 0.026% de expansión en longitud, y 0.91, 2.2 y 1.78% de cambio en peso, respectivamente. Estudios complementarios por difracción de rayos X y microscopía electrónica de barrido revelaron que los cementos CAPSCC tienen un potencial muy bajo para la formación de productos de ataque de sulfato, especialmente etringita. Los resultados confirman una alta resistencia al sulfato de magnesio para CAPSCC en comparación con PC2 y PC5
[en] The paper focused on cement production, limestone use and cement production. No separate emission factors were available, hence the study used a single factor for all the three. The study set four objectives ranging from quantification of carbon dioxide from industrial processes to mitigate options and recommendations
[en] This paper, which is a contribution to the UNEP series on Eco-Efficient Cements, examines the role of material-based solutions to reducing CO2 emissions from cement production considering factors that could influence implementation. Global urbanization has led to an increase in demand for cement and cement-based materials. With its growth in consumption, the associated CO2 emissions from its production are raising concern. However, the role of mitigation strategies in a global context that account for regional material availability and degree of market adoption have yet to be considered. This work shows that the 2 °C scenario targets for 2050 can be met through increased use of calcined clay and engineered filler with dispersants. The introduction of new Portland clinker-based cement alternatives, use of alkali-activated materials, and improvement of efficiency of cement use could further contribute to reduction goals. There are currently-available technologies for reduction that could be rapidly implemented.
[en] FECTO Cement, Islamabad was commissioned in the late 80's to cope the ever-increasing demand of building material in Pakistan. The first ever heavy industry issued license in the Capital area. At that time, environmental issues in Pakistan were merely a subject, discussed only by the professionals in their drawing rooms. The Management of Fecto Cement foresaw the now's burning whirlpool issue and fabricated the company's policy under the slogan ' no race will prosper until it learns the dignity of environmental protection'. The Management's true commitment, consistent, support and steps taken to preserve the biodiversity of eco system in surrounding including Social impacts were discussed. Every industrial process has certain adverse effects on environment. The only way to cope / fight them is approximation, which minimizes those to such an extent that they become appreciably harmless to Biodiversity. Plantation of thousands of plant's and orchids in suburb by Fecto cement, employing costly but highly efficient dust collectors besides Cone's which consume 13 % of the plant energy. To reduce SO/sub x/ in emission gases designing of the efficient and trust worthy Raw meal design, use of low SO/sub x. fuels stagnant Quality Control System and environmentally efficient GMP's enforced in production area plus the supply to municipal facilities like fresh water, schools for children specially girls and jobs to fight the ever increasing unemployment in Islamabad, Made it a prestigious, trust worthy environmental friendly state of the art industrial establishment, which stood as a hallmark and glittering example to other industrial enterprises in Pakistan. (author)