Calcium Ethoxide as Consolidant for Porous Limestones: Influence of the Solvent

Abstract

Calcium ethoxide nanosuspension, a consolidating product developed during the European Nanomatch project, is here modified by adding two different solvents, 2-butanol and n-butylacetate, chosen for their different boiling points with respect to ethanol, the solvent employed in a previous work to dilute the original product. Fourier transform infrared spectroscopy (µFT-IR) was used to understand how the presence of these new solvents can influence the kinetics of the carbonation process and the pathway reaction. Furthermore, coatings derived from nanosuspensions were maintained for specific time intervals at controlled relative humidity conditions (RH = 50% and RH = 90%); the formed mineralogical phases were characterized by µFT-IR and X-ray diffraction (XRD). Results indicate that the used solvents can influence the kinetic and reaction pathways, while the phases formed at the end of the carbonation process are influenced by both solvents and RH conditions. The effectiveness of calcium ethoxide based product diluted in 2-butanol and n-butylacetate as limestone consolidants was evaluated with drilling resistance measurement system (DRMS) and ultrasound pulse velocity (UPV). The impact on color coordinates was also assessed. The results were compared with those obtained with the same product diluted in ethanol and a commercial nanolime. The use of these solvents gave different and better results in terms of efficacy.

A Novel Protection Method for Carbonate Stone Artifacts with Gypsum Weathering Crusts

“…Nevertheless, the slight discrepancy of this peak is not crucial for the confirmation of the calcite as it can shift occasionally; this can also be observed in the other forms of calcium carbonate. Conversely, the peaks of the other forms of the calcium carbonate located at lower wavenumbers, such as calcite (874 and 711 cm −1 ), aragonite (856 and 711 cm −1 ), and vaterite (875 and 745 cm −1 ), are usually not changed under different situations [33,[38][39][40]. Hence, the existence of the calcite can be fully ascertained here; this is in accordance with the XRD results.…”

“…Meanwhile, the peak intensity of the barium sulfate (1080 cm −1 ) also presented the same accumulative trending as that of calcium carbonate, which can be observed in Figure 6. In addition, the intensity of the peak located at 1454 cm −1 for the calcium carbonate almost did not alter at different times; this was observed in the preceding studies [40,42]. However, as depicted in Figure 6, the lengths of the vertical red lines may also stand for the content of the calcium carbonate.…”

Preparation of a new calcite layer from calcium glycolate for the conservation of sulfated limestone artifacts

“…CO 2 was from the atmosphere. Meanwhile, the signals at 1404 and 870 cm −1 were attributed to calcium carbonate, which should come from the hydrolytic reaction of calcium alkyl carbonate (Zuena et al, 2019). The calcium carbonate was further identified as calcite (d = 3.8522 Å, 3.0286 Å, 2.4914 Å, 2.2805 Å, and 2.0938 Å, Figure 4d), the most thermodynamically stable crystal phase in this environment.…”