Preparación de la dosificación de un hormigón con humo de sílice, cuya RMC sea > 40 kp/cm2, a edades iniciales (5-10 horas)

Abstract

Silica fume (SF) or microsilica is related mainly with preparation of High Resistance Concrete. This has justified its use -together with portland cement (I-42'5/SR,MR) and an superfiuidifying additive- in the preparation of a concrete whose value for compressive mechanical resistance at early ages (only 5 to 10 hours) is higher than 40 kp/cm², instead of preparing it with the portland cement plus a setting accelerator or "model" dosage. The experimental techniques used to reach that objective have been: ultrasound energy and a press for breaking 30 x 15 mm specimens, and a maximum load of 2001. With the first technique, in only 25 days, 13 different dossages were prepared, which were compared to the "model" dosage, and two more that did not contain neither setting accelerator nor SF, this means that they had been prepared with the same portland cement, same fine and coarse aggregates and the same consistency, and that they would act as "reference" for all previous ones. In such a way the dosage was found: E, in this case, that was the same as the "model" as for the amount of fine and coarse aggregates, but not as for the amount of the portland cement used which this time was 360 kg/m³ instead of 400kg/m³ SF content 40 kg/m³ and water 144 l/m³