Multi-functional monodispersed SiO2–TiO2 core-shell nanostructure and TEOS in the consolidation of archaeological lime mortars surfaces

Abstract

Archaeological traditional lime mortars are susceptible to many environmental conditions such as the impact of water (rain, humidity, groundwater, etc.), variation of temperatures' degrees, wind and/or pollution. Accordingly, this research aims to provide newly assessed multifunctional Nano-coating for the purpose of archaeological lime mortar protection. For this, the study combined physicochemical and mechanical characterizations in performance assessment of 3%, 5%, and 7% of the synthesized SiO2–TiO2 core-shell nanostructure and TEOS as consolidants on the surfaces of the experimental lime mortars. A series of techniques and tests were fulfilled for the evaluation. For analysis, X-ray diffraction and UV–Vis along with scanning electron microscopy were used to identify microstructure. Furthermore, wettability, colorimetric, self-cleaning, petrophysical, Nano-indentation, and uniaxial compressive strength tests were performed to select the most durable consolidant between 3%, 5%, and 7% SiO2–TiO2/TEOS. Durability assessments were carried out through salt weathering, thermal and UV aging tests. The results showed that 3% and 5% of SiO2–TiO2/TEOS enhanced the physical and mechanical properties of the lime mortars. On the other hand, 7% SiO2–TiO2/TEOS proved their insufficient efficacy in improving the surfaces of lime mortars for the high amount of TiO2 and its behavior for aggregation