In This study, a new laboratory test rig was developed, which can simulate the tribo-system and tribo-mechanism of polishing stage in building stone processing plants as far as possible to eva‎luate the abrasivity of granitic building stones during the stage. Using this rig, a new test method was developed that operational parameters, i.e., the polishing head pressure, head rotation speed, and the water flow rate, are 5 bar, 300 rpm and 4 lit/min, respectively. A building stone abrasivity index (BSAI) was developed via this rig, which defines the weight loss of abrasive tools during polishing for five minutes. The proposed test method was carried out on 15 different types of Iranian granite building stones, and the correlation of obtained BSAI with the physico-mechanical and petrographic properties of stone was investigated via simple regression analysis. Meaningful and reasonable relationships were observed. The results showed that BSAI increases by increasing equivalent quartz content, grain size, the ratio of quartz to all cleavable minerals, overall Mohs harness, texture coefficient, uniaxial compressive strength and Brazilian tensile strength. Moreover, weak correlative relations were seen between porosity and apparent density with BSAI. To eva‎luate the accuracy of the proposed test method, first, the BSAI was compared with two important abrasivity indices of stones. In addition, the laboratory results were compared with data obtained from stone processing plants to validate the proposed test method. Using the developed index, the real life of the abrasive tool in the industry during the polishing process was estimated with acceptable accuracy (R = 0.96 and error less than 15%). eva‎luation of test duration is another topic studied in the present research, which showed a direct relationship between increasing the test duration with the new abrasion index. To investigate the effect of operating parameters on the weight loss of abrasive tools, the base operating parameters were changed between ±25% and ±50%. The results showed that pin weight loss was increased up to a critical pressure and then gradually decreased. This nonlinear wear behavior disagrees with Archardʹs well-known wear law. The FESEM images of worn pin surfaces show that due to excessive load, debonded abrasive particles were unable to pull out from the pin surface, i.e., an interlocking phenomenon occurred between pin and stone surface. It was also observed that pin weight loss increases with the head rotation speed and decreases with water flow rate. Then, for further study and by performing a flow test of seven liters per minute, it was shown that the wear of the pins was almost unchanged. By comparing the results of the effect of operational parameters on the amount of weight loss of abrasive tools, it was detected that the consumption of abrasive tools is more sensitive to changes in the rotation speed of the polishing head. The general findings of the research show that the developed test is a reliable and valuable method for eva‎luating the abrasivity of granite building stones during the polishing process and can properly simulate this process.

ابراهيم قاسمي،‌ هادي حسيني

راحب باقرپور

رسول اجل لوئيان ، مهدي صالحي، سعيد مهدوي