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    Assessment of the results of the pendulum friction tester (EN 14231) for natural building stones used as floor-coverings
    (Elsevier Sci Ltd, 2013) Karaca, Zeki; Gurcan, Sevgi; Gokce, Mehmedi Vehbi; Sivrikaya, Osman
    The main scope and parameter in choosing stone materials for floorings are unquestionably safety and slip resistance. The standard EN 14231 is one of those developed for natural stones. The device used for the tests of this standard, the pendulum coefficient friction tester, determines the slip resistance value of floorings in angle. Standards and their testers have constantly being developed. When this point of view is considered, EN 14231 has not yet been criticized. In this study, EN 14231 and the results obtained by the pendulum tester were for the first time analysed in terms of characteristics expected from a standard. For experimental studies, marble, limestone, travertine and granite samples currently in use as natural building materials were used. For each type of stone, four well-known and widely used stones that had surface roughness less than 1 mm were chosen. In this respect, 384 pendulum tests were conducted on 192 samples and more than 2200 angles were read from F scale. Depending on these readings, the dry slip resistance value-wet slip resistance value (DSRV-WSRV) relationships of marbles, limestone, travertine, and granites were investigated. Except travertine, DSRV-surface roughness and WSRV- surface roughness relationships of the samples were investigated. In addition, DSRV- cavity surface area and WSRV- cavity surface area relationships of travertine samples were investigated. After the evaluation of the test results, it was observed that, in general, higher correlations were obtained from wet samples compared to dry ones. The highest correlations were obtained from wet limestone samples. On the other hand, the lowest correlations were determined on the marble samples. Besides, petrographic characteristics and the physical characteristics of the stones such as, surface roughness and surface cavities were not recorded to have had any determinative effects on the results of the pendulum tester. According to the data obtained in this study, EN 14231 and the pendulum tester were seen to have fallen short in distinguishing both different types of natural stones and different groups of the same type of stone. For this reason, new researches should be made on EN 14231 and the pendulum tester device and both should be developed further. In the light of these results, EN 14231 was concluded to have been unsatisfying in terms of the characteristics expected from a standard and its applicability for slip resistance tests of stone materials to be used in floorings. (C) 2013 Elsevier Ltd. All rights reserved.
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    Grain properties, grain-boundary interactions and their effects on the characteristics of marbles used as building Stones
    (Elsevier Sci Ltd, 2015) Karaca, Zeki; Hacimustafaoglu, Ramazan; Gokce, Mehmedi Vehbi
    In this study, the effects of relationships of micro-structure, grain size and grain boundary of 15 well-known worldwide marbles on some physical and mechanical properties (dry unit weight, porosity, uniaxial compressive strength, tensile strength) and on abrasion loss value were investigated in detail, being the first in terms of elaborateness in the literature considering the mentioned features. 10 different samples were tested for each marble in each test. Microscope images were grouped as intergranular properties (shape of grains, shape of grain aggregates, grain boundary type and pressure solution), intra-granular properties (twinning and alteration) and deformation. All marbles which were tested were found to be of heteroblastic texture. Nine samples were monomineralic marble while six were polymineralic. It was determined that grain characteristics and grain boundary interaction affected dry unit weight, porosity, uniaxial compressive strength, tensile strength and abrasion loss value of each marble tested. (C) 2015 Elsevier Ltd. All rights reserved.
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    Relationship between Slipperiness and Other Characteristics of Stones used as Flooring Slabs
    (Asce-Amer Soc Civil Engineers, 2016) Bellopede, Rossana; Marini, Paola; Karaca, Zeki; Gokce, Mehmedi Vehbi
    Slip resistance is an essential parameter when dimension stones are used as inner and outer floorings. Declaration of performances of stones and their surface finishes (sawn, honed, polished, hammered, flamed, sandblasted, or brushed) in relation to conditions (wet or dry) in Conformite Europeenne (CE) marking is essential for pedestrian safety. In this study, 130 samples taken from 81 stone types belonging to 13 types of petrographic families were tested according to the EN 14231 Standard, taking different finishes into consideration, during a ten-year period in the Marble Laboratory of Politecnico di Torino (Italy). A high number of pendulum friction tests (1,560) were conducted on 780 samples, and more than 7,000 readings were taken. On the basis of the obtained results, significant relations were found between the tested petrographic families and the types of finishes. A high correlation between open porosity, quartz content, and slipperiness of the stones with honed surface finishes was found. Moreover, the importance of the petrographic characterization of the stone, in relation to the declared surface finish, emerged as each petrographic family responded differently (according to its composition) to the action of the finishing abrasive.