Effect of the addition of nanoparticles of <scp>CaCO₃</scp> and different water‐to‐powder ratios on the physicochemical properties of white Portland cement

Abstract

Abstract The addition of calcium carbonate nanoparticles (nano‐CaCO 3 ) accelerates the hydration of Portland cement improving its mechanical properties. Conversely, nano‐CaCO 3 addition leads to reduction in the water required during initial PC hydration. Therefore, the use of a correct water‐to‐powder ratio is fundamental for manipulating this hydraulic cement. This study evaluated the effect of nano‐CaCO 3 addition and different water‐to‐powder ratios on the physicochemical properties of white Portland cement (WPC). WPC was associated to different concentrations of nano‐CaCO 3 , and the following experimental groups were created: G1a (no nano‐CaCO 3 ); G2a (0.5% nano‐CaCO 3 ), G3a (1% nano‐CaCO 3 ), G4a (2% nano‐CaCO 3 ), and G5a (5% nano‐CaCO 3 ). The setting‐time (ST), compressive strength (CS), dimensional change (DC), solubility (S), and pH were assessed (24 hr and 30 days). Next, WPC + 5% nano‐CaCO 3 was manipulated varying the water‐to‐powder ratio: G1b (WPC/0.33 ml); G2b (WPC/nano‐CaCO 3 /0.33 ml); G3b (WPC/0.29 ml); G4b (WPC/nano‐CaCO 3 /0.29 ml); G5b (WPC/0.26 ml); and G6b (WPC/nano‐CaCO 3 /0.26 ml). The tests were repeated. The data analysis (2‐way ANOVA and Tukey test, α = 5%) demonstrated that ST was shorter for samples containing nano‐CaCO 3 ( p &lt; .05). Reduction in CS was observed for all groups at 30 days, except G5a, G2b, and G6b ( p &lt; .05). DC and S had no statistical difference among groups ( p &gt; .05) independently of nano‐CaCO 3 water‐to‐powder ratio. After 30 days, there was significant reduction in pH for G3a and G6b ( p &lt; .05). The different concentrations of nano‐CaCO 3 and water‐to‐powder ratios affected the physicochemical properties of WPC, especially the setting‐time and compressive strength.

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