2. Maestría
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Tesis de la Escuela de Posgrado
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Item Development of an eco-friendly composite based on geopolymer matrix produced with fired clay brick powder and reinforced with natural fibers(Pontificia Universidad Católica del Perú, 2019-02-27) Silva Mondragón, Guido Leonardo; Kim De Aguilar, SuyeonCurrent construction industry is responsible for a large amount of greenhouse gas emissions due to the widespread use of building materials with high-embodied energy such as ordinary Portland cement-based materials and steel. Therefore, this thesis presents the development of a new eco-friendly building material based on a geopolymer matrix produced with Fired Clay Brick Powder (FCBP) and reinforced with natural fibers as a low CO2 alternative for the traditional building materials. With this purpose, a review of recent advances in the application of geopolymer composites and geopolymers reinforced with natural fibers in the construction industry were first presented. This review covers two major eco-friendly materials for construction: first, geopolymers obtained from industrial by-products and waste materials, such as fly ash, ground granulated blast furnace slag, construction and demolition wastes and main tailings; and second, natural fibers used as reinforcement for geopolymer composite materials. Literature review allowed the definition of morphology, size, and the molar ratio of SiO2/Al2O3 in the raw material, together with the alkaline solution/solid ratio, NaOH concentration, SiO2/M2O molar ratio in the total alkaline solution and the curing conditions as key parameters in the formulation of geopolymers. It has been also found that the type, pre-treatment, amount and length of the natural fibers play an important role in the reinforcement of geopolymer matrices. Once key parameters of geopolymer composites production were identified, an attempt for the formalization of a methodology to improve the compressive strength of FCBP-based geopolymers is presented. The tests allowed the definition of optimum conditions of the FCBP-based geopolymers formulation and curing conditions, which resulted in a cementitious matrix with high compression strengths of up to 37 MPa. Nevertheless, high-strength geopolymers evidenced a fragile behavior and low ductility similar to Portland cement-based materials. Therefore, the last part of the work was focused on the evaluation of natural cellulose fibers (jute and sisal) as reinforcement of FCBP-based geopolymers. The results indicated that jute and sisal fiber addition at the optimum content significantly improved the compressive, splitting tensile and flexural strength with respect to the unreinforced geopolymer matrix and lead to a shifting of the failure mode from a brittle to a more ductile failure in all mechanical tests.Item Estudio de la adsorción del fosfato y glifosato presentes en soluciones acuosas utilizando arcillas organofílicas como materiales adsorbentes(Pontificia Universidad Católica del Perú, 2018-10-04) Martínez Bellido, Katherine Maritza; Sun Kou, María del RosarioLa presente tesis se ha centrado en evaluar el estudio de la adsorción del fosfato y glifosato en soluciones acuosas empleando arcillas organofílicas como materiales adsorbentes. Las arcillas organofílicas se obtienen mediante la sustitución de los cationes de cambio presentes en la arcilla precursora homoiónica (CP) con los cationes amónicos cuaternarios hexadeciltrimetilamonio (HDTMA) y tetrametilamonio (TMA) en concentraciones de 1, 2 y 4 veces la capacidad de intercambio catiónico (CEC) de la arcilla. La caracterización de los materiales adsorbentes se ha realizado mediante técnicas analíticas e instrumentales, lo cual permite conocer la morfología, la estructura y las propiedades superficiales de las arcillas. En base a la capacidad de adsorción (qe) de las arcillas organofílicas para la retención de fosfato presente en soluciones acuosas, se ha obtenido el siguiente orden: CP-HDTMA-4> CP-HDTMA-2 >CP-HDTMA-1 >CP-TMA-4 >CP-TMA-2 >CP-TMA-1, en forma similar para el caso de glifosato se ha observado el siguiente orden: CP-HDTMA-4 > CP-HDTMA-2 > CP-TMA-4 > CP-TMA-2 > CP-HDTMA-1 > CP-TMA-1. El tiempo de equilibrio necesario para alcanzar la máxima adsorción del fosfato ha sido de 15 min y para el glifosato ha sido de 20 min. El modelo cinético que presenta un mejor ajuste con los resultados experimentales para la adsorción de ambos adsorbatos ha sido el de pseudo-segundo orden. Para el estudio de las isotermas, la adsorción del fosfato y glifosato han presentado un mejor ajuste con el modelo de Langmuir. En todos los resultados el pH ha sido un factor importante debido a que afecta la capacidad de adsorción, encontrándose que los valores máximos de adsorción para el fosfato y glifosato, han sido a pH=2 y pH=12, respectivamente.