Propiedades de pastas de cementos modificados con residuos industriales

Pastas fueron elaboradas reemplazando cemento portland ordinario por caliza de bagazo de agave, ceniza volante, nano-SiO2 geotérmica y humo de sílice. Las pastas fueron curadas a 20ºC y 100% de humedad hasta 28 días. Se les evaluó la resistencia a la compresión, resistencia a la penetración de iones cloruro, porosidad y microestructura. Tras la evaluación, los resultados revelaron que las pastas reemplazadas mostraron una matriz más compacta y menos porosa, valores de resistencia a la compresión de hasta un 45% más, valores de paso de carga de hasta 57% menos, en comparación con las pastas de referencia

Concretos sustentables expuestos a altas temperaturas

Concretos fueron elaborados reemplazando cemento Portland ordinario por nano-SiO2 geotérmica y humo de sílice. Se curaron a 20ºC y 100% de humedad hasta 7 años y después fueron expuestos a altas temperaturas (350°C, 550°C y 750°C). Se les evaluó la velocidad de ultrasonidos (UPV), análisis termogravimétrico/diferencial (TG/DTA), difracción de rayos X (DRX) y microscopía electrónica de barrido (MEB). La pérdida de peso y la reducción en la UPV fue mayor para los especímenes adicionados (NSG y HS) en comparación con el espécimen de referencia (CPC 100%), además se apreció una mayor degradación en la microestructura de los especímenes con adiciones

Effect of the Microstructures Formed in Cements Modified by Limestone Agave Bagasse Ash, Fly Ash, Geothermal Nano-SiO2 Waste and Silica Fume on Chloride Ion Penetration Resistance

In the present work, pastes were fabricated replacing the ordinary portland cement (OPC) by 0, 1.67, 2.5 and 5 wt% of limestone from agave bagasse ash (ABA), fly ash (FA), geothermal nano-SiO2 waste (GNW) and silica fume (SF), using 1.5 wt% of superplasticizer based in carboxylate and a water/binder ratio of 0.45. After fabrication, the pastes were cured at 20ºC and a humidity content of 100% for up to 28 days. The compressive strength, chloride penetration, porosity and microstructural evolution properties were evaluated. The results obtained from the test suggests that the mechanical, electrochemical, physical and microstructural properties resulting from the cured specimens were enhanced, when compared to the cements obtained with pastes composed by 100% of OPC. It was found that the ABA pastes improved by ~15% to ~25% their mechanical resistance, compared with the values obtained for 100% OPC and 5% FA respectively. Additionally, the pastes containing 2.5% of ABA and 2.5% of GNW, showed an increase of 35% in the values of mechanical resistance in comparison to the 100% OPC. It is also worth mentioning that a the pastes experienced a higher densification value, mainly due to the addition of GNW, which promotes the development of a matrix with reduced porosity when compared with values measured at 100% OPC. The chlorine ion penetration ratio had also low values giving an ion penetration resistance around 57 % less. These results revealed that geothermal nano-SiO2 waste (GNW) and limestone of agave bagasse ash (ABA) could be considered as a potentially suitable material for making pastes, mortars and concrete for industrial applications, which will contribute positively to the reduction of the CO2 emissions into the atmosphere, as well as decrease the environmental impact generated at the disposal zones