Effect of particle size of colloidal nano-silica on the properties of the SCM based concrete

In the current study, effect of particle size of colloidal nano-silica on the properties of the SCM based concrete is studied. The nano-silica particle sizes adopted for the study are 30nm, 60nm and 90 nm. The M20 grade concrete system is made up of cement (C), fly ash (FA), micro-silica (mS) and nano-silica (nS). Compressive strength test at 60 days and pore structure analysis are carried out for C-FA-mS-nS system. The hydration of Portland cement is significantly influenced by the colloidal nanosilica (CNS) particle size. High doses of nS content boost the pozzolanic reaction and the creation of CSH and CASH gels, but they also have a negative impact on the strength development of the material by increasing microcracking due to the self-desiccation effect. The addition of nanosilica to concrete can significantly enhance its qualities after hardening because it ensures the pozzolanic reaction, the seeding effect, which both increase the degree of hydration, and the filling effect, which can fill the internal porosity defects. The cement-mS system's impermeability was greatly improved by the nS because it improved the microstructure, increased the complexity of the pore structure, and refined the pore structure.