Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

Heritage Science

Table 4 The daily P-wave velocity change rates (%) in three stages for the rock samples immersed in water and acidic solutions

Treatment days	Water group	H₂SO₄ groups (mol L⁻¹)			HNO₃ groups (mol L⁻¹)
Treatment days	Water group	0.2	0.4	0.8	0.2	0.4	0.8
I (days 1–4)	− 2.04 ± 0.89	− 4.20 ± 1.77	− 4.83 ± 1.82	− 5.16 ± 2.04	− 2.42 ± 0.89	− 3.24 ± 1.09	− 4.02 ± 1.94
II (days 5–8)	1.30 ± 0.76	− 1.17 ± 0.84	− 1.01 ± 0.79	− 1.06 ± 0.65	− 1.43 ± 0.87	− 1.73 ± 0.54	− 1.55 ± 0.81
III (days 9–19)	0.15 ± 0.08	− 0.32 ± 0.15	− 0.16 ± 0.09	− 0.15 ± 0.08	− 0.34 ± 0.13	− 0.20 ± 0.07	− 0.06 ± 0.04