Highlights:Graphical/Tabular Abstract Preparation of representative sphere test samples Determination of estimated cycle number Utilization of statistical mean control charts in SDI test When the recommendations in the standards and literature have been interpreted, representative test samples using in SDI test should be prepared as equal size, equal mass and smooth surface to be reached approximately ideal SDI value. In this study, multiple cycle SDI tests have been performed on spherical samples with equal size / mass and smooth surface prepared from the massive and laminated marl rock samples, and then the variation of SDI values in the cycles has been determined.
Figure A. Change of SDI valuesPurpose: The aim of this article is to estimate an ideal index values on the representative sphere test samples subjected to slake durability index test by using the statistical tools.
Materials and Methods:The massive and laminated marl sample blocks were collected from Tunçbilek and Seyitömer lignite mines at the Kütahya region in Turkey, respectively. The standards recommend that the shape of representative test samples should be prepared as nearly spherical samples. However, it should be also stated that being nearly spherical is a subjective matter, which changes from person to person. In this study, five different test sets for each rock blocks were prepared as representative sphere test samples by using the new method. The weight of representative sphere test samples in five sets have about 40, 45, 50, 55 and 60 grams each. Then The SDI values were determined for the five different sets subjected to the SDI test for 25 cycles. The amount of mass loss in the cycles have been marked an the statistical mean control charts, and their variabilities have been interpreted. After interpretation, the mean control charts were drawn again and then the lower and upper SDI index values were estimated the range of ideal index values.
Results:In this article, the SDI values should be determined on exactly spherical test samples subjected to SDI test to eliminate the effect of mechanical breakages of representative test samples during rotating the drum. After elimination of breakages, the weights of mass loss among the cycles were marked and interpreted on the mean control charts. In interpretation of control charts, it was suggested that the index values taken after more than two cycles can be useful to reach the ideal SDI values, as given in some literatures. In addition to this, the index values depending on the number of cycles were calculated as lower and upper indices on both massive and laminated marl samples.
Conclusion:In this article, the mean control charts have been determined as an effective tool on interpreting of the amounts of mass loss, and determination of variabilities between the cycles. Furthermore, the limit values of indices depending the variabilities have been represented as a new approach to reach the ideal index values.
Keywords: Slake durability index Mean control chart Massive marl lamina...
