NATIONAL PHD IN HERITAGE SCIENCE

Thesis title: Analysis of Chemical and Physical Degradation Phenomena in Cultural Heritage Materials and Development of Technologies for their Protection and Conservation

This doctoral research integrates the study of decay mechanisms in historic mortars with the development of geopolymer binders as a compatible and sustainable alternative for the conservation of the built heritage. Compatibility is understood in a multidimensional sense—chemical–physical, microstructural, hygric, mechanical, and aesthetic—and is consistently related to breathability, long-term durability, and the principle of reversibility/minimum intervention, within a circular-economy framework that valorises local resources and Construction-and-Demolition Waste (CDW). Metakaolin-based geopolymer mortars were formulated with historically relevant aggregates (zeolitic tuffs of different types and cocciopesto) and subjected to a suite of diagnostic and performance tests: physical and hygric analyses, mechanical tests, thermal measurements, and accelerated ageing cycles (salt crystallisation and wetting–drying), complemented by non-destructive controls (UPV, hardness, colour surveys) to track material evolution without impairment. The tests indicate that—within appropriate design ranges (Si/Al ratio, aggregate selection, liquid-to-solid ratio)—it is possible to obtain geopolymer mortars with properties commensurate with conservation practice, while maintaining a balanced trade-off between performance and colour stability. To bridge the laboratory–site gap, the research was transferred to a real case, the archaeological complex of Carminiello ai Mannesi (Naples), in collaboration with the Heritage Authority: site surveys, targeted sampling, and characterisation analyses supported the selection of the formulation assessed as most compatible from mineralogical and hygric standpoints. Therefore, an on-site pilot intervention was carried out, consisting of the repointing of three selected joints, with the initiation of a long-term non-destructive monitoring programme aimed at assessing adhesion, cohesion, moisture behaviour, and colour stability under real exposure conditions. Ultimately, the combined pathway of design, diagnostics, and field testing does not merely validate a material; it articulates a working methodology. It offers a practicable—cautious, verifiable, and replicable—trajectory that narrows the distance between laboratory and site, positioning geopolymer mortars as a responsible option for historic contexts.