| Popis: |
Structural studies to assess the earthquake resistance of Byzantine monuments have proved that their static and dynamic behaviour depend on the mechanical, chemical and microstructural properties of the masonry mortars and bricks. The crushed brick/lime concrete is classified as an advanced cement-based composite, explain- ing the longevity of Byzantine monuments. More specifically, the Byzantine monu- ment of the Church of St. Michaels in Vydubytskyi Monastery (11 th c.), in Kiev has been studied to provide insights on its effective dynamic properties, during major earthquake in the area. The bricks and mortars are investigated taking under consid- eration the construction technique known as "concealed course", by optical micros- copy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermal analysis (TG-DTA). They were found to allow for continuous stresses and strains due to the presence of the amorphous hydraulic formations (CSH) at the crushed-brick powder/binder interfaces and in the binding matrix, and be able to absorb greater energy without initiations of fractures. The interpretation of the amorphous nature of the hydraulic formations is compared with the use of fine siliceous sources to accelerate the for- mation of hydraulic compounds. The determination of the mortar properties indi- cated that they are of considerable mechanical strength and durability. The results show major similarities with these of the Byzantine monuments in Istanbul (Theo- dosian Walls and Hagia Sophia - 6 th - 11 th c.), giving evidence to earthquake resis- tant construction techniques and materials. Hence, a reverse engineering approach, complying with the deduced criteria is proposed in order to reproduce compatible restoration concrete for earthquake protection of monuments. |
