Functionalized nanoparticles-based surface treatment as an alternative to mitigate deterioration in fired clay materials

The preservation of built and cultural heritage poses numerous challenges globally, given its intrinsic value and historical significance. This study assesses the performance of two surface treatments, comprising a dispersion of functionalized silicon-based nanoparticles at a concentration of 0.1% in water. Two different variants were examined: the first being simple functionalized (NS) "T1" and the second being dehydrated functionalized (NF) "T2" nanoparticles. The application of both treatments, T1 and T2, was carried out on specimens of fired clay tile using a sponge brush in two layers, with 30 min between each layer. These treatments were compared with the application of three commercial products: a 90% siloxane-based reactive grade compound (SX), a solvent-based silicone resin active (C1), and silicone-based active and water-conveyed additives (C2). After application, the specimens were evaluated simultaneously to determine the behavior and effectiveness of the treatments in two different exposure environments (in a natural urban/industrial environment for 24 months and a controlled environment in a QUV chamber for 2000 h). The performance of the treatment was assessed through the measurement of static contact angle, capillary water absorption, and optical appearance in accordance with colorimetric and FTIR standards. It was established that the application of the T2 treatment yields comprehensive outcomes in fired clay tiles as a hydrophobic treatment, imparting advantageous properties. Urban and industrial settings significantly impact visual aesthetics, as reflected in high ΔE* values. Functionalized nanoparticles demonstrate enhanced performance even at low concentrations, making them ideal for preserving the aesthetics and structural integrity of walls and roof tiles in heritage buildings.