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PIETRAFORTE Origin Albania. Petrographic name Lithic arenite Type Siliciclastic sedimentary rock. Macroscopic description Fine-grain clastic rock, grey in color with more yellowish portion (altered), without veins of calcite. Petrographic description under the microscope Mineralogically immature and texturally mature sandstone composed primarily of altered quartz, lithic and feldspar granules (including microcline and plagioclase). The granules are well classed and have a maximum diameter of a few tenths of a millimeter. The lithic component consists of micritic calcite clasts. The trace amounts of other minerals present include granules of muscovite, chlorite, microcrystalline quartz, zircon and opaque minerals. Genetic environment The rock was formed by the accumulation of clastic sediments well classed from granulometric standpoint (absence of matrix). This characteristic indicate a transport agent capable of selecting the granules based on their kinetic energy, so the environment of formation refers both to a fluvial continental environment and a deltaic or coastal marine environment. The composition of the clasts, the quartz and feldspar granules on the one hand and the micritic carbonate granules on the other, indicate that the sediment derived from a mixed-feed basin where both upper-crust carbonatic rocks and medium-lower-crust igneous and metamorphic rocks (crystalline base) outcropped. Results of chemical analysis (% by weight): SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 LOI Tot 51.53 0.299 18.01 0.97 0.66 0.06 17.27 98.80 4.55 2.34 0.222 2.90 Photos under the petrographic microscope The following photos were taken on thin sections. PO-1000! .jpg – Panoramic of quartz , feldspar, and calcite crystals (nicols //) PO- 10002.jpg – Panoramic of quartz , feldspar, and calcite crystals (nicols//) PO- 10003.jpg – K- feldspar, muscovite clasts (nicols//) PO- 10004.jpg – Chlorite (nicols//) PO-10005 .jpg – Microcline clasts (nicols +) PO- 10006.jpg – Zircon and plagioclase clasts (nicols+) PO-10007 .jpg – Microcrystalline quartz clasts (top left) and plagioclase clasts (bottom right) (nicols+) PO-10008 .jpg – Panoramic of quartz, feldspar, calcite and muscovite clasts (nicols +) PO- 10009.jpg – Muscovite clast (nicols +) Flexural strength UNI EN 12372/2001 The flexural strength test was performed according to UNI EN 12372/2001 standard on ten specimens. The following are the minimum, maximum and arithmetic mean values of flexural strength obtained on dry specimens (Rtf ): a Rtf min = 14.0 MPa Rtf max = 19.4 MPa a a mean Rtfa = 17.2 MPa Freeze/thaw resistance UNI EN 1341/2003 The results of the flexure testing described above were compared with those of a flexure test performed on ten specimens subjected to 48 freeze/thaw cycles.. The following are the minimum, maximum and arithmetic mean of the flexural resistance test on specimens subjected to freeze/thaw cycles (Rtf ): g Rtf min = 12.5 MPa Rtf g max = 17.9 g MPa mean Rtfg = 14.8 MPa A comparison of the mean Rtfa values with those of Rtfg shows a slight decrease in flexural strength, so it falls into Class 1, indicating a strength variation less than or equal to 20%, and the material can be described as “resistant” according to table 6 UNI EN 1341/2003. Skid/slip resistance UNI EN 1341/2003 The test performed according to UNI EN 1341/2003 standard Appendix D on six specimens provided the following mean value: USRV = 80