Transporte de agua en hormigón mezclado con residuos puzolánicos. Determinación de los parámetros cinéticos del proceso
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Fecha
2015-06-25
Autores
Palmero Cruz, Norma Caridad
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Editor
Universidad Central "Marta Abreu" de Las Villas
Resumen
En este trabajo se caracteriza cualitativa y cuantitativamente el proceso de absorción de agua en hormigones mezclados con residuos puzolánicos, tales como escoria siderúrgica granulada (GGBS), ceniza de bagazo de caña (CBCA) y ceniza de cáscara de arroz (CCA). Los datos experimentales de absorción de agua por unidad de área fueron extraídos a partir de resultados publicados por (Cordeiro, 2006) y (Mejia, 1997). Los parámetros cinéticos que caracterizan el proceso se obtuvieron aplicando un modelo compuesto capilar-difusivo capaz de describir el proceso de absorción de agua en todas las edades del hormigón, considerando tanto la absorción capilar a través de los grandes poros que tiene lugar mayoritariamente a edades tempranas, como la difusión a través de los poros pequeños y poros de gel que ocurre fundamentalmente a edades tardías. Con el uso del software Gráfula 3.1, fueron obtenidos los datos de masa de agua incorporada por unidad de área M/A Vs. t1/2 a partir de las curvas de los ensayos de los autores mencionados. Para la aplicación del modelo capilar difusivo las curvas son de M/A Vs. t.
De acuerdo con los valores de los parámetros cinéticos calculados se puede afirmar que de los tres materiales puzolánicos analizados el que más disminuye la permeabilidad del hormigón es la CCA incorporado a éste un 20 %, seguido por la CCA 10 %, CCA 15 %, CBCA 20 %, CBCA 15 %, CBCA 10 %, GGBS 70 %, GGBS 60 %. El material que menos disminuye la permeabilidad es la GGBS 80 %. En el caso de los hormigones compuestos con CCA el ajuste del modelo reflejó un comportamiento difusivo puro, no apreciándose un comportamiento capilar-difusivo en los otros casos. Esto está acorde con el inexistente comportamiento supuestamente lineal a edades tempranas que se aprecia en la curva de absorción, sin que exista una pendiente a estas edades que pueda significar algo en este período de tiempo. Los resultados cuantitativos se corresponden con el análisis cualitativo realizado también en el trabajo.
In this work it is characterized quantitative and qualitatively the process of absorption of water in blended concretes with residuals pozzolanic, such as ground granulated blag slag (GGBS), sugar cane straw ash (SCSA) and rice husk ash (RHA). The experimental data of water absorption per unit area were extracted starting from the results published by Cordeiro (2006) and Mejías and Talero (1997). The kinetic parameters that characterize the process is obtained by applying a hair-diffusive model compound capable of describing the process of water absorption in all ages of the concrete, considering both capillary absorption through the large pores at an early age as diffusion through the small pores and gel pores. Using the Grafula 3.1 software, data of water mass incorporated per unit area M / A Vs. t1 / 2 were obtained from the curves of the tests of these authors. For the application of capillary-diffusive model the curves used are M / A Vs. t. According with the values of the kinetic parameters calculated it can be say that of the three analyzed pozzolanic materials the rice hull ash (CCA) is the ash that more decreases the permeability when is incorporated into concrete at 20 %, followed by CCA 10 %, CCA 15 %, CBCA 20 %, CBCA 15 %, CBCA 10 %, GGBS 70 %, GGBS 60 % and finally the material that less decreases the permeability is the ground granulated blag slag (GGBS) incorporated into concrete at 80 %. In the case of concrete added with CCA the fit of the model reflect a pure diffusive behavior, not appreciating a capillary-diffusive behavior as in the previous cases. This is consistent with the nonexistent of the supposedly linear behavior at early ages, which is appreciated in the absorption curve that shows an insignificant slope at these ages. The quantitative results are consistent with the qualitative analysis carried out also in the research work. According to the results, the rice hull ash shows the best results, being an excellent pozzolanic material that diminish greatly the permeability of the concrete, causes a big pore refinement and therefore a significant increase of the durability.
In this work it is characterized quantitative and qualitatively the process of absorption of water in blended concretes with residuals pozzolanic, such as ground granulated blag slag (GGBS), sugar cane straw ash (SCSA) and rice husk ash (RHA). The experimental data of water absorption per unit area were extracted starting from the results published by Cordeiro (2006) and Mejías and Talero (1997). The kinetic parameters that characterize the process is obtained by applying a hair-diffusive model compound capable of describing the process of water absorption in all ages of the concrete, considering both capillary absorption through the large pores at an early age as diffusion through the small pores and gel pores. Using the Grafula 3.1 software, data of water mass incorporated per unit area M / A Vs. t1 / 2 were obtained from the curves of the tests of these authors. For the application of capillary-diffusive model the curves used are M / A Vs. t. According with the values of the kinetic parameters calculated it can be say that of the three analyzed pozzolanic materials the rice hull ash (CCA) is the ash that more decreases the permeability when is incorporated into concrete at 20 %, followed by CCA 10 %, CCA 15 %, CBCA 20 %, CBCA 15 %, CBCA 10 %, GGBS 70 %, GGBS 60 % and finally the material that less decreases the permeability is the ground granulated blag slag (GGBS) incorporated into concrete at 80 %. In the case of concrete added with CCA the fit of the model reflect a pure diffusive behavior, not appreciating a capillary-diffusive behavior as in the previous cases. This is consistent with the nonexistent of the supposedly linear behavior at early ages, which is appreciated in the absorption curve that shows an insignificant slope at these ages. The quantitative results are consistent with the qualitative analysis carried out also in the research work. According to the results, the rice hull ash shows the best results, being an excellent pozzolanic material that diminish greatly the permeability of the concrete, causes a big pore refinement and therefore a significant increase of the durability.
Descripción
Palabras clave
Modelos Matemáticos, Parámetros Cinéticos, Proceso de Absorción de Agua, Hormigones Mezclados, Residuos Puzolánicos, Construcciones Marítimas