Thermal and hygric expansion characteristics of mortars and bricks used in the dome structures of Turkish Baths from 14th and 15th centuries

• Thermal and hygric expansion behaviors of bricks and mortars from historical dome structures were studied.
• TECs of the mortars and bricks from the same dome structure are found to be within tight limits.
• The displacements of mortars and bricks due to increasing RH are comparable within the same structure.

Thermal and hygric expansion characteristics of mortars and bricks from the dome structures of three Turkish Baths from 14th and 15th centuries were investigated. The linear thermal expansion coefficients of the mortars and bricks were determined in the temperature range from −10 °C to 50 °C and hygric expansion characteristics of the same samples were studied in the relative humidity range from 30% to 80%. The results showed that the thermal and hygric expansion characteristics of mortars used in the dome structures of the studied baths are very similar to those of bricks used within the same structure. The thermal expansion coefficients of the mortars are 2.5% to at most 10% greater than the bricks of the same dome. The linear displacement of the mortars and bricks due to relative humidity changes are less pronounced in comparison with the displacement due to thermal changes, but similarity in the expansion trends in between the mortar and bricks of the same structure is also observed for the hygric expansion test results. Since movement of the materials resulting from cyclic changes in temperature or relative humidity may cause stresses at the interfaces where different materials are in contact, eventually resulting in cracks and detachments, it is important to consider the thermal and hygric expansion behavior of the original materials during the selection of repair materials to be used in the conservation works of these dome structures.