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

This study examines the effectiveness of doping SiO 2 nanoparticles onto limestone substrates to mitigate nanoparticle agglomeration, thereby enhancing their performance through improved dispersion within the cement paste matrix. SiO 2 nanoparticles were doped onto the limestone particles using the wet doping method, and the resulting SiO 2 -nanoparticle-limestone composite was incorporated into cement paste systems. To thoroughly examine the effects of SiO 2 -nanoparticle-limestone composite on the properties of cement paste mixtures, SiO 2 nanoparticles with two different specific surface areas (90 m 2 /g and 300 m 2 /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 SiO 2 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 SiO 2 nanoparticles during mixing process. These findings suggest that the SiO 2 -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.