Para hacer un uso más efectivo del humo de sílice en la mejora de la microestructura de la pasta de cemento endurecida., many researchers at home and abroad have conducted more detailed studies on the optimal conditions for the application of silica fume in cement paste and concrete, including the water-cement ratio, the amount of silica fume, the selection of admixtures and other volcanic ash admixtures and their dosage.
Silica fume in cement paste and concrete applications there is an optimal water-cement ratio range, generally beyond the range, Se reducirá el humo de sílice en la pasta de cemento endurecido y la mejora de la microestructura del hormigón..
As a researcher pointed out, a la edad de 3 d o 7 d in cement mortar, the water-cement ratio is less than 0.45 (relación agua-cemento de 0.35, 0.40) of the mortar specimens containing silica fume strength decreases, while the water-cement ratio is equal to 0.45 o 0.50 of the mortar specimens containing silica fume strength increases;
but at the age of 28 d o 90 d in cement mortar, the water-cement ratio is less than 0.35, 0.40, 0.50 The strength of mortar specimens containing silica fume is approximately the same;
while the strength of mortar specimens containing silica fume (independientemente del contenido de humo de sílice) con una relación agua-cemento igual a 0.45 es bajo;
cuando la relación agua-cemento es igual a 0.50 and the silica fume admixture is greater than 27.5%, silica fume has a significant effect on the later strength development of the mortar.
Although silica fume (microsílice) can effectively improve the microstructure of hardened cement paste and concrete, but because of the small particle size and large specific surface area of silica fume, por lo que la pasta de cemento y el hormigón se mezclan con humo de sílice, with the increase of mezcla de humo de sílice, la demanda de agua aumenta, and the self-shrinkage also increases. Por lo tanto, the amount of silica fume is generally limited to between 5% y 10%, and high efficiency water reducing agent to adjust the water demand, al mismo tiempo, there is a compatibility problem between cement, humo de sílice, ingredientes, por lo tanto, when using silica fume must pay attention to its application conditions.
Since the addition of silica fume in concrete may lead to self-shrinkage of concrete, and the addition of silica fume concrete is generally a special requirement of concrete, por lo tanto, the use of silica fume in concrete to harden the cement paste and concrete properties of the beneficial effect at the same time, must minimize the adverse effects brought about by silica fume, the most effective way to solve this problem is the addition of silica fume at the same time mixed with other volcanic ash materials or Other substances, so that they complement each other’s strengths and weaknesses to achieve better technical and economic results. Actualmente, more research is the use of ultrafine slag and silica fume compounding, o el uso de cenizas volantes y humo de sílice compuesto.
Another area of silica fume application conditions are more research is the use of silane on the surface of silica fume pretreatment after mixing into the cement paste or concrete or directly silane and silica fume at the same time into the cement paste or concrete, pueden mejorar la trabajabilidad de la pasta de cemento fresco y el hormigón, mejorando así la microestructura de la pasta de cemento endurecido y el hormigón.
El efecto del humo de sílice en las propiedades del concreto
