EFFECTS OF NANOSILICA ON COMPRESSIVE STRENGTH AND WATER SORPTIVITY OF CONCRETE AT DIFFERENT WATER-CEMENT RATIOS

Abstract

Compressive strength and water sorptivity index (WSI) are among the decisive parameters defining the strength and durability of concrete in corrosive environments. Previous research on concrete technology has largely been attentive to methods to obtain highly resistant concrete. Importantly, marked capillary porosity inside the concrete enhances the ingression of detrimental ions into the concrete. To avoid this, WSI needs to be maximally diminished. Currently, there are some strategies such as the partial substitution of cement with nanosilica (a highly active artificial pozzolan) in the concrete mixing plan to enhance concrete properties. This research explored the effects of adding nanosilica on the compressive strength and WSI of concrete. A total of 336 cube concrete specimens were examined for 7 and 28 days in the Concrete Research Laboratory of Qazvin Azad University. Experiments covered 28 mixing plans involving 1, 2, 3, 4, 5, and 6% cement substitution with nanosilica at water-cement ratios of 0.35, 0.40, 0.45, and 0.50. It was found that adding nanosilica to the concrete mixing plan enhances compressive strength and reduces WSI.