Resistance to salt crystallization of thin-bedded or platy limestone from the town of Benkovac in Croatia

Purpose. This paper aims to show the petrographic microstructural properties of natural stone as a building material from Benkovac, which is exposed to the influence of sea salt crystallization on the Croatian Adriatic coast. Methods. The research is based on the graphical and statistical analysis of the results of polarization and electron microscopy, resistance to salt crystallization, ultrasound propagation velocity and uniaxial compressive strength testing. Three diffe-rent lithotypes of limestone – grainy, micritic and laminated are analyzed to evaluate their important petrographic properties that have impact on the durability when material is exposed to the salt crystallization. Findings. In the petrographic analysis, different characteristics are highlighted, especially those relevant to anisotropy of the structural features as lamination or layering. Besides determination of resistance to the salt crystallization, propagation of ultrasound direct P waves and uniaxial compressive strength are also tested. It is of scientific importance that a change in the internal structure of all samples, especially the laminated lithotype, is observed during the testing. The decrease of ultrasonic propagation velocity, decrease in compressive strength, and durability due to the action of crystallization pressure is a result of increase of the pore space and the fracturing along natural discontinuities such as lamination and layering. Originality. This paper is the first to deal with the resistance to salt crystallization of the Benkovac stone, especially from the point of view of its petrographic properties. It also deals with the new aspect of interpreting the durability results by combining different methods of evaluating properties that are related to each other. Practical implications. The knowledge gained in a specific area of the thin-bedded limestone of Benkovac can also be utilized in other places for better and effective protection and preservation of buildings, for which the same type of stone is quarried and used in construction.