Study on the efficacy of amorphous calcium carbonate as a consolidant for calcareous matrix

Abstract

The popular involvement of amorphous calcium carbonate (ACC) in organisms, usually via a complicated non-classical crystallization pathway, has aroused interest in the scientific community. In recent years, a lot of work has been carried out for the preparation and application of ACC. In this paper, the effectiveness of ACC for the consolidation of calcareous matrix was evaluated. ACC was synthesized through direct carbonation of calcium oxide in ethanol and was introduced into simulated samples as consolidant. A comprehensive study for the assessment of protective effect was carried out by testing surface strength, chromaticity, compressive strength, water vapor permeability, water absorption and freezing–thawing resistance. The results showed that the addition of ACC could significantly improve the surface strength, compressive strength and weatherability of treated samples, while it had only a slight influence on color difference and water vapor permeability. It was confirmed that ACC could connect the loose calcite particles by ‘spot welding’ through heterogeneous nucleation and growth processes. As a consolidant, it demonstrated its merits in this study and could be proposed as an alternative for the protection of weathered calcareous stones.