Improving the performance of SiO2 nanoparticles in portland-limestone cementitious systems using silica-limestone composites

This study examines the effectiveness of doping SiO₂ nanoparticles onto limestone substrates to mitigate nanoparticle agglomeration, thereby enhancing their performance through improved dispersion within the cement paste matrix. SiO₂ nanoparticles were doped onto the limestone particles using the wet doping method, and the resulting SiO₂-nanoparticle-limestone composite was incorporated into cement paste systems. To thoroughly examine the effects of SiO₂-nanoparticle-limestone composite on the properties of cement paste mixtures, SiO₂ nanoparticles with two different specific surface areas (90 m²/g and 300 m²/g) and at various dosages (1.4 %, 2.8 %, and 5.6 % by weight of the total binder) were doped onto the limestone particles. Results show that doping SiO₂ nanoparticles onto the limestone particles reduced the required amount of superplasticizer, decreased calcium hydroxide content through intensified pozzolanic activity, refined the pore structure, and enhanced compressive strength in cement paste systems, compared to the direct addition of colloidal SiO₂ nanoparticles during mixing process. These findings suggest that the SiO₂-nanoparticle-doped limestone composite has the potential to develop cement-based materials with substantially reduced clinker content, enhanced mechanical strength, and a refined pore structure.