New nanomaterials for consolidating stone

The contact angle analysis, scanning electron microscopy measurement, stain resistant test, salt crystallization test and outdoor exposure test were conducted to investigate the effectiveness and durability of this composite coating.Results showed that Si O composite materials created a hydrophobic, crack-free coating with self-cleaning and antibacterial properties on the decayed sandstone surface, allowing their use for practical outdoor sandstone conservation applications.In these last years the nanolime has been applied widely, but despite the rapid increase in the literature on nanolime as a conservation material, it is today necessary to set up more technical and practical studies focalized on real specific cases.For practitioners, it is important to have a broader range of published case studies that describe the nanolime treatment to different environmental situation [4].Nanotechnologies and nanolime, as consolidating materials for architectural and stone surfaces [5], have been developed mainly in the last years, for the capability to solve several problems connected with conventional lime treatments, such as incomplete lime carbonation process, limited depth penetration, and the formation of thin white superficial layers [6].The materials in nanodimensions have specific chemical and physical properties, linked to the physical and chemistry properties of very small particles with respect to the massive materials [7].

The following elements have been pressed in an agate mortar to prepare an homogenous powder subsequently added with 20 m L of distilled water: After 5 minutes of mixing, the aggregate became dense and it has been placed in 5 cm plates where it dried up during the 48 following hours.Callixtus’s catacomb, the site contains a great number of stone materials and wall paintings of great interest from historical, artistic, and religious point of view, by evidencing the necessity to be preserved, protected, and valued in situ.Both stone materials and wall paintings are chiefly made of calcium carbonate matrix (calcareous stones and plaster) aggregated in various structures.What has been described above induced us to consider the influence of relative humidity (RH) and material’s moisture content in the performance of stone consolidation [8]. [11] on lime pastes has shown that lime pastes exposed to 97% RH are resulted to have a higher carbonation rate compared with pastes exposed to 65% RH, where a small amount of calcium hydroxide was retained.The same authors [12] have also studied the strong influence of both relative humidity and particle size on the carbonation rates of lime pastes and lime mortars.

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