Yazar "Yilmaz, N. Gunes" seçeneğine göre listele

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    Abrasion wear characterization of some selected stone flooring materials with respect to contact load
    (Elsevier Sci Ltd, 2012) Karaca, Z.; Yilmaz, N. Gunes; Goktan, R. M.
    Abrasion of stone flooring materials under the influence of foot traffic is mainly a function of the load exerted on them by fine solid particles. This paper presents a study of the abrasion behavior of some natural stone flooring materials when subjected to wear under varying contact loads. Abrasion wear tests were performed on a Bohme apparatus which is widely used in the construction industry for determining flooring suitability of stone tiles. Contact loads ranging from 100 to 500 N were applied for each tested stone material, while keeping the other operational parameters constant. In the case of carbonate stone materials, abrasion wear rate was found to be linearly proportional to the applied load. The granites, however, exhibited a non-linear abrasion wear behavior, not conforming to Archard's well-known classical wear law. It was also observed that, in some cases, changes in the applied load could be an influencing factor in the ranking of flooring materials with respect to abrasion wear rate. (C) 2012 Elsevier Ltd. All rights reserved.
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    Influence of rock cradle block geometry on rebound hardness
    (Springer Heidelberg, 2016) Yilmaz, N. Gunes; Goktan, R. M.; Yavuz, A. B.; Karaca, Z.
    The Schmidt hammer (SH) testing of cylindrical rock cores requires the use of a cradle block (core holder) to hold the cores firmly during the test. For this purpose, the related International Society for Rock Mechanics (ISRM)-suggested method and American Society for Testing and Materials (ASTM) standard suggest the use of an 'arch-shaped' or a 'V-shaped' cradle block. However, there is little or no detailed quantitative information in the literature regarding the potential influence of cradle block type on the measured rebound values (R values). With this in view, an investigation was carried out regarding the influence of cradle block geometry on R values, by employing the two cradle blocks specified in the preceding Standards. Using an L-type Digi-Schmidt hammer, SH tests were performed on NX-size cylindrical cores of 20 different rock varieties, both in 'oven-dry' and 'wet' state. Although the observed differences were usually small, results showed that the magnitudes of the mean rebound values determined in the arch-shaped block (R (A)) were higher than those determined in the V-shaped block (R (V)), except in one case. For the oven-dried samples, lowest and highest differences between the means of R (A) and R (V) values were 0.37 and 5.92, respectively. In the case of wet samples, the differences ranged from a low of 0.33 to a high of 4.70 in R-units. Statistically significant positive linear correlations were observed between R (A) and R (V) values, although the degree of correspondence was relatively lower for rocks having uniaxial compressive strength < 50 MPa. The results of additional SH tests carried out on two different engineering materials also indicated that higher mean rebound values could be attained in the arch-shaped block. The results of the present study did not confirm the findings of a previous study where it was found that the V-shaped cradle block gave consistently higher mean rebound values than the arch-shaped one. The possible reasons for this discrepancy were discussed.