Durability aspects of ancient mortars of the archeological site of Olynthos

Abstract In order to conserve the archeological site of Olynthos, a systematic study of materials preceded. The analysis of mortar samples taken from the remains of ancient Olynthos (400 BC) showed that different qualities of mortars were used for different purposes. Almost impermeable mortars were found in contact with draining canals. This was the initiative to start a combined analysis of mortars by determining their physical and chemical characteristics in order to find the textural features and the alterations of the structure in order to understand their resistance to weathering. The paper focuses on the interrelation of findings from the above-referred examinations. The use of reactive siliceous materials in combination with lime as well as the excellent gradation of aggregates used seems to be the secrets of the good performance of the ancient mortars.