Influence of Hydrothermal Nanosilica on Mechanical Properties of Plain Concrete

The production of nanosilica (NS) from natural hydrothermal solution is an alternative to the existing commercial fabrication methods because of the lower energy requirements. Here we provide a detailed characterization of the main properties of NS samples (e.g., shape and particle size) by different methods. The produced NS has a specific surface area between 60 m2/g and 500 m2/g and nanoparticles sizes between 5 nm and 135 nm. The aim of the present work is to evaluate the effect of the natural NS on compressive strengths of plain concrete. For this purpose, eight series of concrete specimens with different volume fraction of NS are studied. Experimental results reveal that with adding of NS, the concrete strength can be increased by 35% after 28 days, whereas strength characteristics of such concrete can be increased up to 84% after 3 days, and 93% after 7 days compared with a control concrete without NS.