Abstract-Rice husk (RH) is a rich silica by-product of rice production with great potential for industrial applications. After combustion, a rice husk ash rich in silica is obtained, with some amount of other inorganic components constituted mainly of alkaline elements. The study was conducted to characterize both the rice husk and rice husk ash (RHA) in order to evaluate their constitution and the form in which mentioned impurities are present. The amorphous silica crystallized when heated under certain conditions. In this way, the examination of the crystallization process of rice husk ash with different impurity levels was also carried out by varying the temperature, time and heating conditions. The study reveals a preferential distribution of silica at the cell tip of the outer RH surface cells. The impurities form compounds with combinations of different elements such as Ca and Mg, P and K, and are mainly localized below the inner surface in the form of spherical and cuboidal shapes, as well as irregular morphologies. Abstract-Rice husk (RH) is a rich silica by-product of rice production with great potential for industrial applications. After combustion, a rice husk ash rich in silica is obtained, with some amount of other inorganic components constituted mainly of alkaline elements. The study was conducted to characterize both the rice husk and rice husk ash (RHA) in order to evaluate their constitution and the form in which mentioned impurities are present. The amorphous silica crystallized when heated under certain conditions. In this way, the examination of the crystallization process of rice husk ash with different impurity levels was also carried out by varying the temperature, time and heating conditions. The study reveals a preferential distribution of silica at the cell tip of the outer RH surface cells. The impurities form compounds with combinations of different elements such as Ca and Mg, P and K, and are mainly localized below the inner surface in the form of spherical and cuboidal shapes, as well as irregular morphologies..

This study deals with a comparison between water and air cured blended cement pastes at a Water-to-binder (W/B) ratio of 0.3 after ageing for 91 days. Supplementary Cementitious Materials (SCMs) like zeolitic tuffs are widely used to improve compressive strength by the pozzolanic reaction. In this study, mordenite rich tuff, a mixture of clinoptilolite-heulandite-mordenite-calcite, and calcareous siltstone were blended with Ordinary Portland cement (OPC) at levels ranged from 5 to 27.5%. Using quantitative X-ray diffraction (QXRD), Thermal gravimetric analysis-Differential scanning calorimetry (TGA-DSC), as well as density measurements and compressive strength, some hydration parameters such as content of calcium hydroxide (CH), anhydrous cement phases, calcite, and water in hydrates, density and the mechanical performance were determined. The results showed that hydration process of blended cement pastes was uncomplete at ages as late as 91 days regardless of curing conditions. The air cured cement pastes showed a less content of CH, water in hydrates, and compressive strength, but instead a higher density and content of carbonate-like minerals with respect to their water-cured counterparts. The pozzolanic reaction scarcely proceeded at a W/B ratio of 0.3 regardless of curing condition. Among the SCMs, mordenite rich tuff blended cement pastes presented the best compressive strength values, when was cured under water; the others showed better values of compressive strength in air curing condition.

Abstract-Nanocomposites of high density polyethylene (HDPE)were prepared by conventional equipment for polymer processing using three different organo-clays (5% by weight) with maleic anhydride grafted polyethylene bonding agent (20% by weight). One of the clay is originated from Peninsula de Santa Elena (Group Ancon) of Ecuador. The nanocomposites were processed by a simple screw extruder and injection molding. The extruder was made using dispersive and distributive elements to improve the dispersion of the organo-clays in to the polymer compound. The microstructures of the organo-clays and nanocomposites were determined by X-ray diffraction. Tensile and impact test were performed to evaluate its mechanical properties. The effects of the organo-clays in the thermal stability and crystallinity of HDPE were measured by thermogravimetric analysis (TGA) and dynamic scanning calorimetry (DSC), respectively. Organo-clay dispersion in the polyethylene was observed by SEM and visually. Improvement in the mechanical, thermal, and dispersion properties of the nanocomposites developed using the orgao-clays found in Ecuador were observed. Resumen-Nanocompuestos de polietileno de alta densidad (HDPE) fueron preparados con equipos convencionales de procesamiento de polímeros utilizando tres diferentes organoarcillas (5% por peso) con un agente de enlace basado en anhídrido maléico polietileno grafted (20% por peso). Una de las arcillas es originaria de la Península de Santa Elena (Grupo Ancón) de Ecuador. Los nanocompuestos fueron procesados usando una extrusora de tornillo simple y una inyectora de moldeo. El tornillo del extrusor fue fabricado con elementos dispersivos y distributivos para mejorar la dispersión de las organoarcillas en la matriz polimérica. La microestructura de las organoarcillas y los nanocompuestos fueron determinados por difractometría de rayos X. Propiedades mecánicas fueron evaluadas a través de ensayos de tensión e impacto. El efecto de las organoarcillas en la cristalinidad y estabilidad térmica del polietileno fueron determinados por calorímetro dinámico de barrido y análisis termo-gravimétrico, respectivamente. La dispersión de las organoarcillas en el polietileno fue observada por microscopía electrónica de barrido y visualmente. Se observaron mejores propiedades mecánicas, térmicas y dispersión de los nanocompuestos desarrollados con la organoarcilla originaria de Ecuador. Keywords--Palabras claves-Nanocompuestos, HDPE, organoarcilla, propiedades, producción, industrial.Abstract-Nanocomposites of high density polyethylene (HDPE) were prepared by conventional equipment for polymer processing using three different organoclays (5wt%) with maleic anhydride grafted polyethylene coupling agent (20wt%). One of the clay is originated from Peninsula de Santa Elena (Group Ancon) of Ecuador. The nanocomposites were processed by melt blending in a single screw extrusion and injection molding. Dispersive and distributive elements in the single screw improved the melting compounding. The microstructures of t...

Abstract-. The goal of this paper is to provide a basis for the sustainable development of the cement and construction industry. Both of them involve environmental impacts as a result of the increased demand of their products and services. There is a concern about the adverse effects to sustainable development, and this have led to develop more efficient technologies in the cement industry, however there are still several problems and associated consequences. Considering the above, the approach used in this paper is the environmental evaluation of cement production from alternative raw materials, in this case zeolites.The methodology known as life cycle assessment (LCA) was used to quantify the environmental impacts. The study results showed that the environmental burden of the zeolite-based cement is higher than the ordinary Portland cement. Nevertheless, this outcome is due to the scale at which the study was conducted, therefore the environmental burden would be diminished if the production process is done on an industrial scale.