Diagnosis and Proposal for Restoration of Masonry Structures Damaged During the War - An Example of Examination of VijećNica (City Hall) In Sarajevo

Abstract

Thermal shock, that takes place in masonry structure during the fire, induces chemical and physical changes in stone and mortar. Chemical changes usually do not occur immediately but after certain time and they are connected with the kind of burning material. For example, the burning of plastic materials produces chlorides while the burning of certain paints produces sulfates. These harmful products of burning, contained in smoke, diffuse deeply into the mortar and after some time they destroy the compactness of binding material.

The destruction process is accelerated if the mortar is in a wet environment (capillary moisture, condensation, rain leakage etc.) because sulfate and chloride salts crystallize during vaporization, enlarge their volume and destroy the structure of mortar and stone.

The high temperature causes mortar separation, larger mortar porosity, peeling and cracks in the stone.

In order to estimate the damage of masonry material caused by high temperature, the temperature values and fire duration must be known.

The masonry materials and elements have been tested for required heating, but each fire is different, depending on many factors such as the quantity of burning material, the type of material, the storage method and burning characteristics. The quantity of ventilation is very important factor, too.

The preliminary results of the examination of City Hall (Vijećnica) in Sarajevo will be given in this paper as a practical example of derived diagnosis.