PEG-assisted controlled precipitation of calcium hydroxide and calcium carbonate nanostructures for cement reinforcement

Herein, we have developed simple, one-stage and cheap precipitation methods for synthesizing Ca(OH)(2) and CaCO3 nanoparticles with average sizes of (75 +/- 8)0.95 and (70 +/- 10)0.95 nm, respectively. Both methods are based on CaCl2 precursor and cheap polyethylene glycol (PEG) surfactant. The influence of the precipitation conditions on the size and morphology of crystallites was studied, and the required conditions for the formation of anisotropic crystals of Ca(OH)(2) and CaCO3 were identified. Preliminary studies showed that all concentrations of isotropic CaCO3 nanoparticles increased the flexural and compressive strength of 2-day cement by more than 50% and more than 30%, respectively. The best overall result was achieved with 0.06% of CaCO3 nanoparticles, which increased the compressive and flexural strength of 28-day cement by approximate to 9% and approximate to 12%, respectively. The compressive strength of all the samples with Ca(OH)(2) nanoparticles at 2 days and 28 days increased by more than 20% and more than 5%, while the flexural strength of all 2-day cements increased by more than 25%.

Automated summary

The study demonstrates that adding different concentrations of CaCO3 nanoparticles can significantly improve the mechanical properties of cement. Among all experiments, 0.06% CaCO3 nanoparticles showed the best performance. Additionally, the addition of Ca(OH)(2) nanoparticles also leads to a noticeable increase in the mechanical strength of cement.