The Investigation of Nano Silica in the Cement Hydration Process

With the advent of nano technology, materials have been developed that can be applied to high performance concrete mix designs. Nano silica reacts with calcium hydroxide (CH) to develop more of the strength carrying structure of cement: calcium silica hydrate (CSH). In this paper, relationships have been developed to distinguish the benefits when using different sizes of nano silica in cement paste. An extensive regime of experimental analysis was carried out to determine the effect of nano silica. Through these experiments the heat of hydration of multiple cement mix designs was measured. After that, the concentration of CH was recorded through X-ray diffraction. Then, the grain structures were examined through Scanning Electron Microscopy. Finally, the compressive strength was determined for each cement paste mixture. Through these experiments it was found that as the silica particles decreased in size and their size distribution broadened, the CSHs became more rigid; this increased the compressive strength.