Assessment of new protective treatments for porous limestone combining water-repellency and anti-colonization properties

Abstract

Water is known to be the main deteriorating agent of building geomaterials. Owing to the presence of water, the alteration phenomena observed particularly on limestones are transportation of soluble salts, dissolution of calcite and development of micro-organisms. In restoration works, several chemical treatments can be used, such as biocides to remove existing biofouling and water-repellents to prevent the ingress of water and its deteriorating effects. The aim here was to combine these two properties in one treatment that could be applied at the end of the restoration work and to develop treatments based on natural products and that are safer for the users and the environment. Products with water-repellent and/or anti-colonization properties were developed and tested on a bioclastic limestone both in laboratory and outdoor conditions. They were compared with commercial water-repellents and a preventive anti-colonization treatment. Samples were exposed for 2 years in a forest environment, where the hydrophobicity and the colonization were evaluated every 6 months. In the laboratory, anti-colonization effects were determined through algae growth measurements. The product that confirmed an efficient hydrophobicity and anti-colonization effect will be applied on a restored site to test it under real conditions.

A new preventive coating for building stones mixing a water repellent and an eco-friendly biocide

“…More precisely, 51.6 % of pore access radii are larger than 1 µm, 41 % are between 1 and 0.1 µm and 7.4 % are between 0.1 and 0.01 µm. The capillary coefficient C1 relative to the weight increase per surface and per square root of time unit is 146 g.m -2 .s -1/2 [34] and implies good connectivity in the intergranular macroporosity. Such characteristics make the stone particularly sensitive to weathering like heterogeneous disintegration [35] and mainly favour a bioreceptivity that results in a significant greening of the stone [36].…”

Efficacy of different chemical mixtures against green algal growth on limestone: A case study with Chlorella vulgaris

“…This study attempts to develop a preventive treatment using a solegel process applied onto a clean surface (Eyssautier-Chuine et al, 2014). Tetraethoxysilane (TEOS), commonly used as a consolidant, was used here as a precursor at low concentrations.…”

Early detection of micro-organisms development on stone monuments thanks to the stimulated infrared thermography and SVD

“…At the final state, the weakness of the stone leads to its breakdown. Colourimetry is a usual NDT which assesses the biodeterioration of the stone through its colour change [1][2][3] but the settlement of pioneer bacteria can not be tracked by this method because of the lack of colour. IRT as a NDT has been investigated to detect pioneer biofilms before the visible soiling of walls to limit the cleaning.…”