Effect Of Ultra-fine Active Silica Powder On The Concrete Properties

A new type of supplementary cementitious material (SCM):Ultra-fine Active Silica Powder (UASP), had been studied. Firstly, the pozzolanic activity of UASP was determined by the method of lime absorption. Secondly, the pozzolanic activity of UASP was calculated by the method of mortar strength. Subsequently, the optimum dosage of UASP in cement pastes and mortar were determined. Successful preparation of the C40 and C50 series of concretes mixed with UASP. The mechanical property, workability and durability of UASP concrete were tested. The methods of X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were used to test the cement pastes in the different types of concrete. The studies show:(1) The mechanical properties of cement paste had been significantly improved by adding UASP; there have a optimum dosage of UASP in cement pastes;(2) UASP has very strong pozzolanic activity. The compressive strength results of mortar indicate that the pozzolanic activity of UASP is weaker than SF;(3) Successful preparation of C40 and C50 two series of concretes mixed with UASP.(4) As an effective concrete mineral admixture, UASP can significantly improve the mechanical property and workability.(5) An appropriate dosage of UASP can improve the durability of concrete.(6) Adding UASP to concrete can significant reduce the amount of CH in cement pastes, and then reduce the amount of directional CH crystals around the ITZ. Meanwhile, adding UASP to concrete can improve the microstructure of concrete. In conclusion, UASP can improve the mechanism of concrete.