Influence of nanoparticles on fluidity and mechanical properties of cement mortar

• Nanoparticles content affected directly on the fluidity of cement mortar.
• Mechanical properties of cement mortars modified nanoparticles were tested.
• Increasing nano-ZnO content significantly restrains the hydration of mortar.
• Enhancement mechanism of nano-SiO2 on mortar was studied by SEM and XRD.

Nanoparticles are potentially effective microstructural reinforcements for cementitious composites. Many properties of composites may change with the addition of nanoparticles. In this work, the workability, mechanical and microstructure properties of mortar containing four kinds of nanoparticles were evaluated, and these four kinds of nanoparticles were nano-Al2O3, nano-SiO2, nano-TiO2 and nano-ZnO respectively. Test results showed that the increasing addition of nano-SiO2 and nano-Al2O3 led to the increased water demand while nano-TiO2 and nano-ZnO had little effect on the mortar fluidity. With 3% (by weight of cement) nano-SiO2 particles, the 7 days flexural and compressive strength increased by 17.8% and 9.5% respectively. Nano-ZnO prolonged the setting time of mortar significantly, furthermore, the compressive strength was much lower than that of control specimen at early age. The influence of nanoparticles on the hydration degree, fluidity and mechanical properties of cementitious mixes were analyzed by using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD).