Valorization and optimization of residue of masonry for the production of self-compacting concrete

El empleo de diferentes materiales cementicios suplementarios (MCS) en la elaboración de concretos autocompactantes (CACs) es una práctica cada vez más frecuente. En este artículo se presentan resultados de una investigación acerca de la utilización del residuo de mampostería (RM) como MCS. El material se caracterizó utilizando la prueba de Frattini, índice de actividad de resistencia y termogravimetría. La influencia del RM en las propiedades del CAC se evaluó reemplazando el cemento Portland en porcentajes de 0 a 50% en volumen. Las propiedades en estado fresco de los CAC se evaluaron mediante los ensayos de flujo de asentamiento con cono de Abrams, caja en L y embudo en V. Los resultados muestran que el RM presenta actividad puzolánica y puede ser empleado como MCS. El CAC elaborado con RM presentó buen comportamiento en términos de autocompactabilidad; sin embargo, el RM, al presentar baja reactividad a edades tempranas, mostró disminución en la resistencia a la compresión en forma directamente proporcional al porcentaje de reemplazoThe use of different supplementary cementitious materials (SCM) in the production of self-compacting concretes (SCCs) is an increasingly common practice. In this paper, results of a research about the use of residue of masonry (RM) as SCM are presented. Frattini test, resistance activity index and thermogravimetry testing were carried out. The influence of RM on the fresh and hardened properties of the SCC was studied by replacing the Portland cement in percentages of 0 to 50% by volume. The fresh properties of the SCCs were measured by slump flow test, L-box and V-funnel. The test results showed that the RM has pozzolanic activity and can be used as SCM. The SCC manufactured with RM presented good performance in terms of self-compactability; however, the RM, because of its low reactivity at early ages, showed a decrease in the compressive strength, that was directly proportional to the percentage of replacemen

Modeling a bending resistance modulus for a cementitious material compound based on properties in fresh state

En la presente investigación se estudió la relación entre las propiedades del estado fresco y el estado endurecido de un material compuesto formado por una matriz de cemento Pórtland reforzado con fibra de fique dispuestas al azar, las propiedades evaluadas en estado fresco fueron: ondulabilidad, fluidez, drenabilidad y en estado endurecido el módulo de la resistencia a la flexión. Las muestras se prepararon con diferentes materias primas (Fibra de fique, Bentonita, Pulpa, Humo de Sílice y Acronal), las componentes se agregaron a una mezcladora a velocidad constante, luego se vertió la mezcla en una cámara de drenado donde se extrajo el agua y se conformó la lámina con dimensiones de 130x50x6 mm, luego se sumergió en una piscina de curado por 28 días para ser evaluado el módulo de la resistencia a la flexión. El modelo de regresión lineal que se propuso para predecir el módulo de la resistencia a la flexión, en función de las propiedades en estado fresco, se realizó a través del análisis de las interacciones entre las variables de la formulación de la mezcla utilizada. Como resultado del modelo de regresión se obtuvo que existe una clara correlación entre el módulo de la resistencia a la flexión y las propiedades predictoras ondulabilidad, fluidez y drenabilidad, además estas tienen un efecto negativo sobre el módulo de la resistencia a la flexiónIn this research we studied the relationship between fresh state and hardened state of a fiber reinforced laminate compound (MCLRF), respectively, based on a matrix of Portland cement. The variables that have been worked in the fresh state were undulation ability, flow ability and drain ability and hardened in the form of resistance to bending, (bending resistance modulus). The samples were prepared with different raw materials (fique fiber, bentonite, pulp, silica fume, and Acronal). The ingredients were grinded by a mixer working at a constant speed, after that, the mixture was poured into a drainage chamber, and the water was extracted, forming a sheet with dimensions 130x50x6 mm, finally, it was immersed in a curing chamber for 28 days, for bending evaluation. The linear regression model proposed to predict the bending resistance modulus, considering the properties of in fresh state, was performed through the analysis of interactions between variables in formulation of the mixture used. From the regression model it was found that there is a clear correlation between bending resistance modulus and the predictive variables: undulation ability, flow ability and drain ability. Furthermore, the variables have a negative effect on the bending resistance modulu

Optimization of the technological properties of porcelain tile bodies containing rice straw ash using the design of experiments methodology

This study examines the effects of replacing fluxing and filler materials with rice straw ash (RSA) in manufacturing porcelain stoneware tile, using the design of experiments (DOE) methodology. The results of the characterization were used to obtain statistically significant, valid regression equations, relating the technological properties of the dried and fired test pieces to the raw materials content in the unfired mixtures. The regression models were analysed in relation to the X-ray diffraction and scanning electron microscopy results and used to determine the most appropriate combinations of traditional raw materials and RSA to produce porcelain stoneware tiles with specific technological properties. The studied range of tile body compositions: clay (40 wt%), feldspar (20–50 wt%), feldspathic sand (5–20 wt%), and RSA (0–25 wt%) was shown to be appropriate for porcelain stoneware tile manufactur

Optimization of compressive strength using design of extreme vertices mixing, in ternary concretes based on masonry residue and hydrated lime

La búsqueda de materiales alternativos que sustituyan parcialmente el cemento Portland debido a la problemática ambiental que presenta este en su producción, nace la necesidad de investigar el empleo de mezclas ternarias (cemento Portland de uso general (OPC), residuo de mampostería (RM) y cal hidratada (CAL) para mejorar las propiedades de los concretos y disminuir su impacto ambiental. En este sentido, esta investigación realizo un diseño de mezclas de vértices extremos para estudiar el efecto del empleo de RM proveniente de residuos de construcción y demolición (RCD) y CAL como sustitución parcial del cemento Portland (hasta un 20 % en peso) en concretos ternarios en la resistencia a la compresión a los 28 días de curado. Por otra parte, se evaluó las propiedades en estado fresco (asentamiento) y endurecido, como la resistencia a la compresión, tracción indirecta, absorción y porosidad y succión capilar. Los resultados mostraron que a mayor porcentaje de reemplazo de RM y menores de CAL presentaron mejores resistencias a la compresión que cuando se presentaba mayores porcentajes de cal hidratada. La resistencia a la compresión aumentó en 25,1% y 16,1% a los 28 y 60 días de curado con respecto a la mezcla patrón.The search for alternative materials that partially substitute Portland cement is important because of the environmental problems that this presents in its production, hence the need to investigate the use of ternary mixtures (Portland cement for general use (OPC), masonry residue (RM) and hydrated lime (CAL) to improve concrete properties and reduce their environmental impact. According to this, the present research did a design of extreme vertices mixing to study the effect of the use of RM from construction and demolition waste (RCD) and CAL as partial substitution of Portland cement (up to 20% by weight) in concrete ternary in the compressive strength after 28 days of curing. On the other hand, the properties in fresh state were evaluated (slump) and hardened state, such as compressive strength, indirect tensile strength, absorption and porosity and capillary suction. The results showed that a higher percentage of MR replacement and lower CAL had better compressive strengths than when higher percentages of hydrated lime were present. The compressive strength increased by 25.1% and 16.1% at 28 and 60 days of curing with respect to the reference mix.Na busca de materiais alternativos que consigam substituir parcialmente o cimento portland devido ao problema ambiental que gera em sua produção, nasce a necessidade de pesquisar o uso de misturas ternarias (cimento Portland de uso geral (OPC)), resíduo de alvenaria (RM) e cal hidratada (CAL) para melhorar as propriedades dos concretos e diminuir seu impacto ambiental. Neste contexto, a presente pesquisa fez um desenho de vértices extremos misturando para estudar o efeito do uso de RM de resíduos de construção e demolição (RCD) e CAL como substituição parcial do cimento Portland (até 20% em peso) em ternário de concreto na resistência à compressão após 28 dias de cura. Por outro lado, as propriedades em estado fresco foram avaliadas (slump) e estado endurecido, como resistência à compressão, resistência à tração indireta, absorção e porosidade e sucção capilar. Os resultados mostrarem que maiores porcentagens de substituição de RM e menores de CAL apresentam maiores resistências a compressão que com o aumento no conteúdo de cal hidratada. A resistência aumentos em 21 e 16 % aos 28 e 60 dias de curado respeito a amostra padrão