Effect of Binder Proportion and Composition on the Strength and Microstructure of Colloidal Nanosilver–Modified Mortar and Concrete

The present study explores the application of colloidal nanosilver (cAgNPs) in cement composites and compares the performance with commercial silica nanoparticles (SiNPs). Unlike SiNPs, the addition of cAgNPs improves workability and reduces the superplasticizer dosage. The effect of cAgNPs and SiNPs addition was studied for control and fly ash and alccofine blended mortar specimens with binder to filler (b/f) ratio of 1∶2 and 1∶1 at water binder ratios of 0.5 and 0.25. The addition of cAgNPs to control and blended mortar specimens at a 1∶2 b/f ratio exhibits early strength reduction of 14%–34% and 25%–37%, respectively, whereas the same increases by 15%–45% and 50%–100% for a b/f ratio of 1∶1. In addition to strength, the thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) studies confirm reactivity of cAgNPs and its dependence on the binder system, while field emission scanning electron microscopy (FE-SEM) confirms the enhanced microstructure densification. The study demonstrates that the nanoparticles inclusion contributes to increased paste demand and exhibits the beneficial effects of cAgNPs for improved workability and strength.