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Feasibility study on safety and health method of preparing cement paste by adding nano functional additives at the same time

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Document pages: 13 pages

Abstract: The use of a mixing method based on a new dry dispersion procedure is reported. This method can properly mix nano functional additives while avoiding the health risk of exposure to nanoparticles, and is compared with the common manual mixing in this work. This dry dispersion method allows greater processability by avoiding problems associated with particle dispersion. These two mixing methods have been used to prepare Portland cement CEM I 52.5r slurry, in which nano ZnO and micron or nano pozzolan SiO2 with bactericidal properties are added. The hydration processes performed by the two hybrid methods were compared to determine the efficiency of using the method. Hydration analysis of these cement pastes at different ages (fromne to twenty-eight days) by means of differential thermal analysis and thermogravimetry (DTA-TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) analyses. Regardless of composition, all the mixtures of cement pastes obtained by the novel dispersion method showed a higher retardation of cement hydration at intermediate ages which did not occur at higher ages. In agreement with the resulting hydration behaviour, the use of this new dispersion method makes it possible to prepare homogeneous cement pastes with simultaneous functional nanoparticles which are physically supported on the larger particles of cement, avoiding exposure to the nanoparticles and therefore minimizing health risks. Manual mixing of cement-based materials with simultaneous nanometric functional nanoparticles on a large scale would make it difficult to obtain a homogenous material together with the health risks derived from the handling of nanoparticles.

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