Nanoparticles as concrete additives: Review and perspectives

Nanoparticles are highly efficient additives for modification of cement products, even at small concentrations (≤1%). The main modifications are (typical ranges shown, though great variability has been observed): reduction of set time (by 1-2 h) and diffusivity (by 4-75%), and increase of strength (by 5-25%), and thermal durability (0-30% increase in residual strength). These modifications were attributed to the unique reactivity of nanoparticles associated with their small size and large surface area. The paper reviews documented observations of SiO2, Al2O3, Fe2O3, TiO2, CaCO3, and clay nanoparticles, and discusses effective modification mechanisms and commercial application challenges, including cost and dispersion.