Investigation of a suitable porous stone for the restoration work on the Acropolis circuit wall

Abstract

The present work describes the research that was carried out to define a suitable replacement or supplementary stone to use in the restoration work of the circuit wall of the Acropolis in Athens, Greece. The main original building material of the wall is known as Aktitis stone, originating from the ancient quarries of Piraeus, which are no longer accessible. Given the constant exposure to a combination of decay agents, the building materials of the Acropolis wall have begun to present various weathering patterns that gradually have reduced their mechanical properties. When the stability of the structure is threatened and it is not possible to use fresh stones of the same type as the original, it is necessary to use an alternative compatible replacement stone during the restoration. Therefore, an evaluation of eight porous stone samples originating from active quarries in Sitia (Crete), Afytos (Chalkidiki) and Pitsa (Corinthia) in Greece was carried out, through various methods, including determination of physical and moisture transfer properties, uniaxial compression strength tests and color parameter measurements. Moreover, to study the resistance of the samples in the crystallization of soluble salts, accelerated aging tests were performed in sodium sulfate cycles. A comparative evaluation is made between the quarry stones and the original, to draw conclusions about the appropriate materials for use in the upcoming interventions.