Tatiana Durmekova

Changes in Marble Quality After Sodium Sulphate Crystallization and Long-Lasting Freeze-Thaw Testing

This paper summarizes research results about the quality and durability assessment of marbles from Slovakia quarries or outcrops, as well as marbles imported to Slovakia for building purposes through standard laboratory tests—the salt crystallization test and the frost resistance test. For this research of salt crystallization effects, nine various marbles were studied. The mineral composition, microstructure and changes in physical properties of marbles were characterized. One type of the examined marbles, the Thassos marble from Greece, was submitted to detailed research through the use of electron visualization methods and X-ray microtomography. It was discovered that the cyclic salt crystallization caused a decay of this dolomite marble predominantly along dominant crystal boundaries. X-ray microtomography allowed for visualization in 3D with possibility to obtain information about processes of cracks creation. It was possible to characterize parameters of newly created cracks as to their length, width and persistence. Long-lasting cyclic freeze-thaw tests confirmed the satisfactory quality of twenty Slovak marbles and their suitability to all-purpose applications.

Experience from Investigation of Tectonically Extremely Deteriorated Rock Mass for the Highway Tunnel Višňové, Slovakia

The designed highway tunnel Visňove will cross the mountain ridge Lucanska Fatra in Slovakia in its length of 7.48 km. The selection of the tunnel alignment was preceded by a preliminary geological investigation, which indicated a complex geological structure. Consequently, a pilot tunnel was included into the planned geologic investigation. Two tunnelling methods were tested. Complicated geologic structure, intensive faulting and fracturing of rocks and intricate hydrogeological condition were proved by the pilot tunnel. Excavation of the pilot tunnel was variable, all rock mass behaviour types occurred. Enormous problems were linked with negotiation of sudden concentrated inflows of groundwater from fault zones reaching up to 160 l/s, followed by groundwater erosion.