Iron Oxide Nanoparticles Incorporated Cement Mortar Composite: Correlation between Physico-Chemical and Physico-Mechanical Properties

It is now well-understood that incorporation of nanoparticles can enhance the physico-mechanical properties of cement mortar composites. However, there is still little information on the influence of the dosage and chemistry of nanoparticles on the physico-chemical properties of the composites. In this paper, nano-modified cement mortar composites containing 0.0, 2.0, 2.5 and 3.0 wt% of iron oxide (IO) nanoparticles were prepared and their mechanical properties including compressive and flexural strengths were investigated. The results show that the influence of nanoparticle addition is mainly on the growth and change of the calcium silicate hydrate (C–S–H) crystals, which ultimately has an impact on the mechanical properties of the composite. The microstructure and morphology of the composites characterized using scanning electron microscopy (SEM) have shown that composites containing IO have a more compact microstructure with no micro-cracks compared to the plain mortar composite. It is also shown that a composite containing 2.5 wt% IO exhibits the highest compressive and flexural strengths. It is found that the IO nanoparticle at 2.5 wt% dosage not only prevents the formation and propagation of micro-cracks, but also contributes to the improvement of the accessibility of the water molecules to the IO oxygen groups and cement C–S–H. These findings are promising by establishing correlations between the physico-chemical and physico-mechanical properties of IO-reinforced cement mortar composites, which contribute toward using IO to improve the mechanical properties of cement mortar composites.