Improvements of mechanical and physical features of cement mortar by nano Al2O3 and CaCO3 as additives

The current research aimed to investigate the impact of Al2O3 and CaCO3 nanoparticles on the properties of cement mortar. The research methodology primarily focused on preparing mortars using Al2O3 nanoparticles with a mean diameter of ~50 nm and CaCO3 nanoparticles with a particle size of 100 nm. These were utilized at three different substitution levels of 1, 3, and 5% by weight of cement as binary blending materials. The mechanical and physical properties of the cement mortar (compressive strength, density) were tested after 7 and 28 days, while ultrasonic pulse velocity was tested after 28 days of water curing. The experimental results illustrated that utilizing Al2O3 nanoparticles improved the mortar’s compressive strength at an early age (7 days of curing) more than at 28 days, with 3% substitution being the optimal proportion. Similarly, the use of CaCO3 nanoparticles as a binary blending mixture at substitution levels of 1, 3, and 5% by cement weight improved the compressive strength at an early age (7 days of curing) more than at 28 days. The optimal proportion was again 3%, with 87 and 40% improvement for 7 and 28 days of curing, respectively. When comparing Al2O3 and CaCO3 nanoparticles, the latter yielded better results than Al2O3 nanoparticles for both early and later ages. The combined effect of substituting 1 and 3% of Al2O3 and CaCO3 nanoparticles in cement mortar increased compressive strength by 28 and 74% at 7 days of curing and by 30 and 42% at 28 days of curing, respectively.