Laboratory Evaluation of a Graphene Oxide–ESTEL Nanocomposite for Adobe Consolidation: Implications for Future Validation at Sudus, Saudi Arabia

Earthen architectural heritage is highly vulnerable to moisture, erosion, salt activity, and progressive loss of cohesion, creating a need for consolidants that improve mechanical performance without obscuring the limitations of laboratory-to-field transfer. This study evaluates a graphene oxide–ESTEL (GO–ESTEL) nanocomposite as an exploratory consolidant for adobe under controlled laboratory conditions in Egypt and discusses, separately, how the results may inform future validation at Sudus, Saudi Arabia. Laboratory specimens and non-Sudus reference adobe fragments were characterized using polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), computed tomography (CT), and uniaxial compressive strength testing. A fixed exploratory formulation based on a 3 wt.% aqueous GO dispersion combined with ESTEL was applied to the adobe specimens. The treated specimens showed denser microstructural features and improved particle bridging in SEM observations, while CT imaging provided complementary qualitative visualization of the internal structure of the treated adobe. Average maximum compressive load increased from 340.60 to 486.87 kgf, corresponding to a 42.94% increase; maximum displacement and strain at failure decreased by approximately 36.8%. These results demonstrate short-term laboratory strengthening of the tested adobe formulation, but they do not establish long-term durability, an optimum GO concentration, or direct compatibility with Sudus materials. The Sudus survey is therefore retained only as an application context and monitoring framework rather than evidence of field effectiveness. Site-specific mineralogical characterization, environmental monitoring, formulation optimization, accelerated ageing, and controlled pilot trials are required before any conservation application at Sudus or comparable heritage sites.