A study on strength and corrosion protection of cement mortar with the inclusion of nanomaterials

Nanomaterials are highly efficient additives for the modification of microstructure, resulting in better mechanical properties and durability of concrete/mortar. This study investigates the effect of three different dosages (1%, 3% and 5%) of nano-SiO2 and nano-TiO2 on workability, mechanical strength, and corrosion resistance of fly ash-based cement mortars. It was found that the workability of mortar decreases with increase in percentage of nanoparticles, and it was more pronounced for the mortar mix made with 5% nano-SiO2. In contrast, yield stress and viscosity were significantly higher compared to the control mix. Similarly, higher compressive strength was observed for the mortar made with both nano-SiO2 and nano-TiO2 compared to the control mortar. For instance, at 56 days, the compressive strength increased by 50% and 26% for mortar made with 3% nano-SiO2 and 1% nano-TiO2, respectively. The flexural strength result shows an increase at 1% nano-SiO2 and nano-TiO2 content. Beyond this level, the flexural strength decreases, especially for nano-SiO2 mortar. Furthermore, the inclusion of nanoparticles in cement mortar enhances the corrosion resistance of the mortar compared to control samples. Lower mass loss, lower pitting depths of the rebar, and shorter crack length were observed. Scanning electron microscopy and energy-dispersive x-ray measurements show better performance of mortar mixes made with nanoparticles compared to the control mix due to the denser matrix, more C-S-H gel and low Ca/Si ratio.