Historic Zagreb Cathedral restored with Cortec

08 July 2013

The gothic-style Zagreb Cathedral, built in 1093 and the tallest building in Croatia, attracts thousands of tourists. Recently Cortec provided a solution for it restoration.

Since low-quality stone was used in the past owing to economic reasons, it soon started to deteriorate, affected by weather and city pollution (smog and chemical factors). Even though during the Communist era in Croatia, reconstruction was not allowed, some reparations were made thanks to donations from Croatian Diaspora.

The final reconstruction started in 1990 and has been going on ever since, by phases and priorities. Zagreb Archbishopric's Committee for Reconstruction of the Cathedral was founded as well as a task force of selected experts.

The Committee selected Cortec for the reconstruction of its towers owing to the recommendation of the Faculty of Mechanical Engineering and Naval Architecture in Zagreb.
During reconstruction work on the south tower, damaged steel bands were detected surrounding the tower about every 3m in height. The bands were covered with rust and in drainage areas, there was visual damage to the diameter of the bands.

Economical approach with a minimum of intrusion to the structure was required to fix the condition of the bands. The mechanical resistance and structural stability of the tower needed to be maintained or improved. Faculty of Mechanical Engineering examined the bands and performed experiments on the steel bars. They recommended removal of loose corrosion from the bands surfaces, enhancing the bands in the areas of damage and application of Cortec's anti-corrosion protection product- CorrVerter.

CorrVerter is a water-based primer said to quickly convert rust into a protective layer and is capable of penetrating into the depths of corroded surfaces. It contains a novel chemical chelating agent that modifies surface rust into a hydrophobic passive layer. Two-layers of CorrVerter coating were brushed onto smaller surfaces and sprayed in larger areas directly onto the metal bands. The bands were then reinforced with steel fishplates that were welded on the bands and also protected with CorrVerter.

CorrVerter coating penetrated to the non- corroded part of the metal and is said to have stopped further advancement of the corrosion process.

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