Pozzolanic Reactivity of Volcanic Breccia from Euganean Hills: Sustainable Lime-Based Binders for Historic Building Restoration

The environmental impact of Portland cement production has intensified the search for sustainable alternative binders, particularly for historic building restoration where material compatibility is essential. This thesis investigates the pozzolanic reactivity of white volcanic breccia from the Euganean Hills (Padova, Italy), a material historically used in Roman constructions, combined with different lime-based raw materials to develop greener alternatives for restoration applications. Eight mix designs were systematically evaluated using combinations of portlandite, quicklime, slaked magnesia lime, and magnesium oxide. The investigation employed quantitative X-ray powder diffraction (XRPD) to assess phase assemblages at 28 and 60 days, kinetic XRD to monitor early hydration (first 24 hours), and scanning electron microscopy (SEM) for microstructural characterization and elemental mapping. Results demonstrate that binder selection fundamentally controls reaction kinetics and phase development. The dissertation confirms the pozzolanic potential of Euganean Hills white breccia and identifies distinct performance profiles suitable for different restoration requirements. However, continued microstructural evolution beyond bulk chemical stability suggests that standard 28-day testing protocols may inadequately assess natural pozzolan systems. Future research should investigate M-S-H phase formation and extend monitoring periods to fully characterize long-term performance for practical restoration applications.