El efecto de la introducción de nanopartículas base silicio (NBS) preparadas por sol-gel en la permeabilidad de materiales base cemento portland fue estudiado. La introducción de NBS en morteros fabricados con una relación a/c de 0.65 fue inducida durante el curado por 72h, utilizando suspensión de [NBS]=0.1% vs. el volumen del agua. Posteriormente, las muestras siguieron un periodo de inmersión en agua potable con el fin de promover la reacción de la NBS con la matriz cementante y la resistividad fue medida frecuentemente. Después, fueron expuestos en ambientes con Cl- o CO2. Los resultados indicaron una disminución en la penetración de estos agresivos y un incremento de la resistividad en los especímenes tratados; por ende un incremento de la vida útil.
In recent years, biomineralization process is being employed in development of bioconcrete, which is emerging as a sustainable method to enhance the durability of concrete by way of increasing compressive strength and reducing the chloride permeability. In this study, different bacterial strains isolated from the soils of the Laguna Region of Mexico were selected for further study. ACRN5 strain demonstrated higher urease activity than other strains, and the optimum substrate concentration, pH, and temperature were 120 mM, pH 8, and 25 °C, respectively. Further, Km and Vmax of urease activity of ACRN5 were 21.38 mM and 0.212 mM min, respectively. It was observed that addition of ACRN5 at 10 cells ml to cement-water mixture significantly increased (14.94%) in compressive strength after 36 days of curing and reduced chloride penetration. Deposition of calcite in bio-mortars was observed in scanning electron microscopy and energy dispersive X-ray diffraction spectrometry analyses. Results of this study demonstrated the role of microbially induced calcium carbonate precipitation in improving the physico-mechanical properties of bio-mortars.
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