Properties of Cement Composites Modified with Silica-magnetite Nanostructures

Abstract

The incorporation of nanosized particles into the building materials can significantly influence their properties. Such noticeable modification of the properties of cement-based composite is not possible with traditional cement binders and mineral additives. Heavyweight cement concretes are used for production of the radiological shields in the objects exposed to ionizing radiation. In the case of nuclear reactors, concrete is also exposed to a high temperature at the moment of failure. In the presented work authors investigated the properties of the cement composites modified with core-shell type nanostructures. The study is aimed at the development of new material solution showing improved shielding properties of the concrete. Magnetite nanoparticles coated with silica shell were applied to increase the resistance of concrete to elevated temperature, without deterioration of its shielding ability. Plain cement paste and cement paste containing 5 wt% magnetite/silica core-shell structures were prepared. The samples were exposed to temperatures elevated to 300 oC and 450 oC, respectively. Nanoindentation technique was applied for the analysis of mechanical properties of cement pastes. The results have confirmed the favorable role of the Fe3O4/nSiO2 nanoparticles in the protection of the cement matrix from the high temperature.