Publications Details
Sol-gel preservation of mankind`s cultural heritage in objects constructed of stone
Monuments, buildings, and works of art constructed of carbonate-based stone (calcite, e.g., limestone and marble) are subject to deterioration resulting from the effects of environmental exposure, granular disintegration, freeze/thaw cycles, and salt recrystallization. This damage can potentially be reversed by the use of mineral-specific chemical passivants and consolidants that prevent hydrolytic attack and mechanical weakening. The treatment strategy combined the use of calcite coupling molecules to passivate the surfaces against new weathering with alkoxysilane strengthening or consolidating layers to arrest physical deterioration. The authors report on the effectiveness of passivating agents designed through a combined approach of modeling their adhesive and passivating properties using computations at the molecular scale and testing those properties using simulated leaching tests, microscopic evaluation, and characterization of mechanical strength. The experimental results indicate that there may be a threshold binding energy for the passivant above which the dissolution rate of calcite is actually enhanced. Passivant/consolidant treatments were identified which showed substantial reductions in the leach rate of calcite exposed to simulated acid rain conditions.