Samples of mortars were collected from lime and hydraulic mortars affected by environmental degradation. A total of 63 samples were obtained from Hellenistic, Late Roman and Byzantine historic constructions located at Kavala, Drama and Makrygialos in North Greece. Samples were collected in sections from the surface up to 6 cm deep using a drill-core material. The first sample was collected from the external layer, while the internal samples were collected each 1cm beeper from the previous, in order to monitor the moisture ingress. Isotopic data will make it possible to create an ideal Hellenistic and Byzantine mortar layer and to provide weathering gradients. The isotopic values comprise a range of δ13C and δ18O values from −17.1‰ to 1.2‰ and −25.9‰ to −2‰, respectively. The weathering process of Hellenistic and Byzantine are expressed, by the regression lines δ18Ocalcite matrix = 0.6 × δ13Ccalcite matrix − 1.9 and δ18Ocalcite matrix = 0.6 × δ13Ccalcite matrix − 2.0 for hydraulic and Lime mortars respectively. Pronounced isotopic shift to heavy or light δ13C and δ18O in the carbonate matrix was attributed to the primary source of CO2 (atmospheric versus biogenic) and H2O (evaporation of local primary water), in residual limestone and in secondary processes such as recrystallization of calcite with pore water and salts attack. Exogenic processes related to biological growth are responsible for further alterations of δ18O and δ13C in lime mortars. This study indicated that stable isotope analysis is an excellent tool to fingerprint the origin of carbonate, the environmental setting conditions of mortar, origin of CO2 and water during calcite formation and to determine the weathering depth and the potential secondary degradation mechanisms.

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Bulk samples of mortars were collected from archaeological sites dated from Hellenistic to Roman period in order to investigate the technological evolution of historic structures from simple lime based systems to advanced hydraulic materials. Roman opus caementicium enabled the construction of vaults with a mechanical behaviour of an inert monolith; the rapidly hardened mortar with its concrete-like strength provided a monolithic effect on lighter vaulted structures. The samples were characterized in terms of their isotopic, chemical and mineralogical composition. Stable isotope analysis ( 13 C and 18 O) provided information relative to the origin of CO 2 and water during calcite formation making possible to distinguish different mortar technologies. The results of micro-morphological and petrographic examination elucidate the technological continuity of historic mortars. Hellenistic mortars are composed of lime enhanced with quartz aggregates. Roman mortars are composed of lime, pozzolan and various aggregates such as quartz, feldspar, ceramic and rock fragments. The isotopic values comprise a range of δ 13 C and δ 18 O values from −17.6‰ to 3.6‰ and −25.9‰ to 0.4‰ very different from that of local limestones used for mortar production. This study indicated that stable isotope analysis is an excellent tool to fingerprint the origin of carbonate and therefore indicate the variations in mortar's technology.

Samples of mortars were collected from lime and hydraulic mortars affected by environmental, mainly water induced degradation. Moisture and humidity possesses a main threat for the preservation of historic monuments. Agents of decay related with water such as acid rain, sulfate attack, acid attack, leaching action, salts attack, damage due to frost and many more can cause extensive cracks and total disintegration of historic constructions. 50 samples were obtained from historic constructions located in North Greece. Isotopic data will make possible to provide weathering gradients. The samples were characterized in terms of their isotopic, chemical and mineralogical composition. Compositional and morphological analyses were achieved using energy dispersive X-ray analysis in the scanning electron microscope. The results of micro-morphological and petrographic examination elucidate the different sources of degradation of historic mortars. Stable isotope analysis ( 13 C and 18 O) provided information relative to the origin of CO 2 and water making possible to distinguish different sources of waterinduced degradation. This study indicated that stable isotope analysis is an excellent tool to fingerprint the origin of water -induced degradation and to determine the weathering depth and the potential secondary degradation mechanisms.