Properties of cement-based materials incorporating byproduct colloidal nanosilica

Colloidal nanosilica is a byproduct of the etching process used in silica wafer production. This study assessed the effect of nanosilica incorporation on the performance of cement mortar and analyzed the influence of nanosilica based on mineralogical and microstructural characteristics. Tests regarding the flow, isothermal calorimetry, and compressive strength of cement mortars, and X-ray diffraction, Fourier transform infrared spectroscopy, mercury intrusion porosimetry, and compressive strength of cement pastes were performed at 3 and 28 days. The nanosilica-incorporated samples exhibited higher compressive strengths than the control sample. They did not exhibit pozzolanic reactivity but provided a pore-filling effect. At an early hydration age, the nanosilica particles refined the pore size and contributed to a reduction in the total porosity, leading to an enhancement in the compressive strength. Among the hydration products, the difference in Ca(OH)2 between the nanosilica-incorporated samples and control samples was confirmed. During hydration, the difference in Ca(OH)2 is assumed to be due to the blocking of the growth of Ca(OH)2 by the nanosilica particles. •Colloidal nanosilica byproducts generated from silicon wafer processing were used.•Compressive strengths increased with the addition of the nanosilica byproducts.•Difference in Ca(OH)2 between samples was confirmed resulting in pore refinement.•Growth of Ca(OH)2 during hydration may have been blocked by nanosilica particles.