The influence of curing and thermal treatment temperaturę on the microstructure of CAC binder with nano additives

Abstract

The incorporation of nano additives into the cement matrix in order to obtain real cementitious nanocomposites presents an important research problem. This work analyses the effect of nanoSiO2 (NS) on the hydration of CAC, cured at different temperatures (5o C, 20o C, and 40o C) and after thermal treatment (at 800o C, 1000o C), and subsequently on the microstructure and phase composition of hardened cement paste, when W/C=1. After three days of hydration at different temperatures the following crystalline hydration products were found to have formed: CAH10 at 5o C, CAH10 and C2AH8, at 20o C, and C3AH6 and AH3 hydrates at 40o C. Additionally, the XRD results of hardened samples revealed a higher relative intensity of XRD peak of hydrates in the samples with NS compared to the samples without NS. In the samples fired at 800o C the hydrates decomposed, CA, CA2 and C12A7 minerals formed, higher amounts of minerals formed in the samples with NS. The results of XRD analysis of the samples fired at 1000o C showed that the intensities of XRD peaks of CA and CA2 minerals increased, whereas the XRD peak of C12A7 decreased in all samples tested.