The impact of colloidal nanosilica on concrete performance: compressive strength, ductility, and microstructural analysis

In this study, we investigate the effects of colloidal nanosilica on the compressive behaviour and ductility of concrete. The primary objective is to understand how varying percentages of colloidal nanosilica, influence the mechanical properties and microstructure of concrete over different curing periods. The methodology involves preparing concrete specimens with specified nanosilica content and conducting comprehensive tests, including compressive strength, field emission scanning electron microscopy, and X-ray diffraction analysis. Key findings indicate that while the incorporation of colloidal nanosilica generally reduces the compressive strength of concrete, it significantly enhances its ductility. For instance, at seven days, the ductility increases by 26%, 36%, and 65% for samples containing 5%, 10%, and 15% nanosilica, respectively. The FESEM analysis reveals that nanosilica improves the microstructure by reducing porosity and promoting pozzolanic reactions. However, higher nanosilica content results in an irregular nanoparticle structure, contributing to the reduced compressive strength.