S. Demirdag

Analysis of the alterations in porosity features of some natural stones due to thermal effect.

Three types of commercially available carbonate rocks were used in the study to determine the effect of thermal treatment in the range from 100 °C to 500 °C on porosity features in terms of two different approaches such as pore shape factor and quality index values. The ratio of the ultrasonic velocity measurements before and after water saturation was used to differentiate porosity of pores from porosity of cracks under varying temperatures. It was found that, pores in Burdur Beige and Usak White are in the form of cracks, which are situated through inner structure. On the other hand, pores in Patara Limestone are in the form of porosity with lower pore shape factor values. Quality index calculation is another approach based on the comparison of the measured and theoretical ultrasonic velocity values. When the rocks were subjected to higher temperatures, internal stress was developed, crack lengths and numbers were increased and finally the higher pore shape factor and lower quality index values were obtained. This situation was proven by the higher water absorption values for all the stone types with the higher pore shape factor and lower quality index values depend on the noticeable increase in effective porosity values.

Investigation into Variations of Saw Rotation and Noise Level in Cutting by Circular Saw

Doğaltaş işleme teknolojisinde kayaçları kesmek için en çok elmas soketli dairesel testereler kullanılmaktadır. Bu testerelerle kesim sırasında kayaca bağlı olarak önceden ayarlanmış çevresel hızda ve oluşan gürültü seviyesinde değişim görülmektedir. Çalışmada, kayaç kesme deneyleri sırasında testerenin boştaki ve yükteki durumuna göre gürültü seviyesi ölçümleri ve testerenin devir ölçümleri yapılmıştır. Buna göre görece gözenekliği düşük, dayanımı, sertliği ve özgül enerji değerleri yüksek kayaçlarda testerenin tam yükteki devir sayısı boştaki devir sayısına oranla yaklaşık % 1 oranında azalma göstermiştir. En yüksek azalma değeri kireçtaşlarında (bejler) ölçülürken traverten, limra ve andezitte daha düşük devir azalma değerleri ölçülmüştür. Gürültü seviyesindeki artış oranları ise yaklaşık % 6.46’ya kadar en yüksek andezit ve bazalt kayacında meydana gelmiştir. In natural stone technology, to cut rocks circular diamond saws are widely being used. With these saws some variations are seen on pre-set peripheral speed and occurring noise level according to the rock type during cutting. In this study, in rock cutting experiment by circular saw, spindle speed and noise level measurements were made both when cutting and standing idle. About 1% decrease was showed saw spindle speed when cutting according to idle at rocks having low porosity, high strength, hardness and specific energy value. While the highest decrease value was measured at limestone, a lower speed reduction values was determined in travertine, lymra and andesite. The highest noise level increases approximately 6.46% was occurred in andesite and basalt.