Core size effect on the dry and saturated ultrasonic pulse velocity of limestone samples

• Published in: Ultrasonics 2016-12, Vol.72, p.143-149
• Main Authors: Ercikdi, Bayram, Karaman, Kadir, Cihangir, Ferdi, Yılmaz, Tekin, Aliyazıcıoğlu, Şener, Kesimal, Ayhan
• Format: Article
• Language: English
• Subjects: Calcite; Calcite minerals; Clay minerals; Core sample length; Drying; Fluctuation; Limestone; P–wave velocity; Rock; Stabilization; Trends; Water effect
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2016.08.006

•Saturated limestone samples produced lower UPVs and UCS than those of dry samples.•Carbonate minerals played an important role for UCS and UPV of samples.•The UPVs of limestone samples increased or decreased with increasing sample length.•The optimum sample length was determined as 75mm for the UPV test. This study presents the effect of core length on the saturated (UPVsat) and dry (UPVdry) P-wave velocities of four different biomicritic limestone samples, namely light grey (BL-LG), dark grey (BL-DG), reddish (BL-R) and yellow (BL-Y), using core samples having different lengths (25–125mm) at a constant diameter (54.7mm). The saturated P-wave velocity (UPVsat) of all core samples generally decreased with increasing the sample length. However, the dry P-wave velocity (UPVdry) of samples obtained from BL-LG and BL-Y limestones increased with increasing the sample length. In contrast to the literature, the dry P-wave velocity (UPVdry) values of core samples having a length of 75, 100 and 125mm were consistently higher (2.8–46.2%) than those of saturated (UPVsat). Chemical and mineralogical analyses have shown that the P wave velocity is very sensitive to the calcite and clay minerals potentially leading to the weakening/disintegration of rock samples in the presence of water. Severe fluctuations in UPV values were observed to occur between 25 and 75mm sample lengths, thereafter, a trend of stabilization was observed. The maximum variation of UPV values between the sample length of 75mm and 125mm was only 7.3%. Therefore, the threshold core sample length was interpreted as 75mm for UPV measurement in biomicritic limestone samples used in this study.