Characterization of waste nano-silica rich sludge from photovoltaic production processes

This progress report presents the initial stage of the project. The activities carried out during the first eight months (effective date of start: April 2011) of the project can be divided into three parts. Fists, 3 different batches of the silica sludge received from South Korea were physically and chemically characterized. These features are important to the application and design of concrete mixtures. Thus, the characterization techniques included: scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), nitrogen physical adsorption isotherm (BET, t-plot and BJH methods), density by Helium pycnometry, particle size distribution determined by laser light scattering (LLS) and dynamic light scattering (DLS). Second, a dispersability study was performed to design stable slurries to be used as liquid additives during the concrete production on site. Finally, the third activity performed includes the testing of the designed slurries using an isothermal calorimeter and the mechanical testing of standard mortars with 7% of cement replacement to determine the puzzolanic activity of the waste nano-silica sludge.