Factors affecting the serviceability of granite pegmatite floor facing tiles

The aim of the research work has been to define the factors causing the destruction of polished granite pegmatite tiles used for indoor flooring. Facing tiles made of various-size-grain and large-to-giant-grain rocks (mica-quartz-feldspar composition) have been studied using a transmitted-light microscopy method (OLYMPUS BX51 microscope and Steindorff stereoscopic laboratory microscope, 170-BD-LED-E model). The natural features of the granite pegmatite that affect the endurance of the facing tiles have been studied, i.e. the mineral composition and structural-textural properties of the granite pegmatite tiles, as well as the mineral percentage, the grain size and interrelationships have been defined. It has been found that that the tile endurance depends on a crystalline-media property connected with the minerals’ internal structure. The studied tiles consist of plagioclase, microcline, quartz, muscovite, biotite, and garnet. The structure is heterogeneous, varying from fine-grain to giant-grain (crystalline-grain), with alternating fine-grain, medium-grain and large-to-giant-grain structure areas. The minerals are mainly hard (6-7 by the Mohs scale of hardness), except for the mica (2-3). The muscovite and plagioclase have perfect and perfect cleavage, respectively. The cleavage is associated with the anisotropic cohesive forces acting among the regularly arranged structural units in the minerals’ lattice. The mica’s cleavage is a slip plane, which affects the endurance of the facing tile and causes cleavage fracture and subsequent chipping and breakdown. The coarse-crystalline plagioclase has perfect cleavage in two directions, i.e. under vertical load it splits in two directions on the cleavage. Thus, a conclusion can be made that the muscovite’s and plagioclase’ crystalline structure causes cleavage fracture of the facing tiles and their further destruction

facing materials, minerals, cleavage, hardness, structure and texture, pegmatite, crystal lattice

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