Advanced mortar coatings for cultural heritage protection : Durability towards prolonged UV and outdoor exposure

In the present work, two kinds of hybrid polymeric\u2013inorganic coatings containing TiO2 or SiO2 particles and prepared starting from two commercial resins (Alpha\uaeSI30 and Bluesil\uaeBP9710) were developed and applied to two kinds of mortars (an air-hardening calcic lime mortar [ALM] and a natural hydraulic lime mortar [HLM]) to achieve better performances in terms of water repellence and consequently damage resistance. The two pure commercial resins were also applied for comparison purposes. Properties of the coated materials and their performance were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Tests were also performed to determine the weathering effects on both the commercial and the hybrid coatings in order to study their durability. Thus, exposures to UV radiation, to UV radiation/condensed water cycles and to a real polluted atmospheric environment have been performed. The effectiveness of the hybrid SiO2 based coating was demonstrated, especially in the case of the HLM mortar

Self-healing polymeric coatings

Coatings have become one of the most ubiquitous end applications for polymeric materials. Introducing self-repairing mechanisms into coatings is one way to ensure a high level of performance and an extended service life-time, with reduced energy and cost efforts with maintenance and repair. This chapter presents a revision of the self-healing approaches and mechanisms that have the potential to find applications in the broad and challenging smart coatings field. It discusses some of the systems/mechanisms, in light of main molecular interactions that can be used to introduce intrinsic healing mechanisms on polymeric coatings: (i) molecular chains inter-diffusion and segregation, (ii) reversible bonds, and (iii) noncovalent bonds. Many of the current functional polymeric coatings rely on their surface chemical groups for a special performance or functionalities, such as extreme water repellence, self-cleaning behavior (via superhydrophobic or superhydrophilic mechanisms), or anti-(bio)adhesion (i.e., low adherence of proteins and other biofoulants)

Smart hybrid coatings for cultural heritage

The protection of stone monuments against deterioration has recently attracted much attention from scientists. An accurate analysis of the degradation mechanisms of stones has led to the conclusion about the necessity of protection especially against the condensed water and the salts formation. In this study the strengthening effect of nanoparticles-based treatments applied on marbles surfaces is compared to that exhibited by silane commercial polymers. The surface properties of these types of smart coatings were investigated by different analytical techniques such as contact angle measurements, to gain information on surface hydrophobicity and super-hydrophobicity, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), to characterize the surfaces morphology. Aimed at evaluating the superior performance of hybrid coatings , exposure tests both to UV ageing and to atmospheric pollution in a highly polluted typical urban environment, were carried out. Furthermore both bare and coated samples were submitted to aging tests in a Q-UV tester cabinet (1000 h of exposure to UV radiation). Diffuse Reflectance Spectroscopy (DRS) was employed for the CIELab colorimetric coordinates assessment, while Ion Chromatography (IC) was employed to evaluate the coating capacity to avoid salts (Cl-, NO3- and SO42-) formation. Water vapour permeability and water absorption by capillarity were also evaluated