Ca (OH) 2 Nanoparticles Based on Acrylic Copolymers for the consolidation and protection of Ancient Egypt Calcareous Stone Monuments

The deterioration of lime-based porous materials used in artistic/architectural field (lime-based wall paintings, calcareous stones) is one of the most serious problems facing conservation today. The aim of this study was to... [ view full abstract ]

The deterioration of lime-based porous materials used in artistic/architectural field (lime-based wall paintings, calcareous stones) is one of the most serious problems facing conservation today. The aim of this study was to evaluate the effectiveness of inorganic compatible treatments, based on nano sized particles of calcium hydroxide (slaked lime) as a consolidation and protection material dispersed in acrylic copolymer, poly ethylmethacrylate/methylacrylate (70:30) (Poly (EMA/MA), for calcareous stone monuments and painted surfaces affected by different kinds of decay, thanks to the conversion of lime into calcium carbonate. Calcium carbonate is, as a matter of fact, very compatible with many carbonatic lithotypes and architectonic surfaces, because its characteristics are very similar to those of the materials to be restored.
The synthesis process of Ca (OH)2 nanoparticles/polymer nanocomposites have been prepared by in situ emulsion polymerization system. The prepared nanocomposite containing 5% of Ca (OH)2 nanoparticles showed obvious transparency features and represent nanocomposites coating technology with hydrophobic, consolidating and well protection properties.
Some tests are performed in order to estimate the superficial consolidating and protective effect of the treatment; the obtained nanocomposites have been characterized by TEM, while the penetration depth, re-aggregating effects of the deposited phase and the surface morphology before and after aging was examined by Scanning electron microscopy (SEM), Improving of stone mechanical properties were evaluated by compressive strength tests, Changes in water-interaction properties were evaluated by water absorption capillarity measurements and colorimetric measurements were used to evaluate the optical appearance.
All the results converged in individuating these nanometric particles of slaked lime as an innovative, completely compatible, and efficient material for the consolidation of artistic (lime-based wall paintings) and architectural (lime stones) surfaces,Ca (OH)2 /polymer nanocomposite enhanced the durability of limestone toward thermal aging and improved the stone mechanical properties compared to the samples treated with pure acrylic copolymer without Ca (OH)2 nanoparticles.