Slaking is one of the most basic characteristics of swelling rocks. However

criteria refer to slaking and characteristics of collapsed scraps are rare among rapid identification and classification criteria available. Thus

it is necessary to explore into slaking and grain size distribution (GSD) of the dry collapsed scraps of swelling rock and their relationships with the level of expansibility

which can complete the rapid identification and classification criteria with respect to slaking. With argillaceous rock samples collected from Daban Tunnel in Xinjiang Uygur Autonomous Region

and Heidong Cavern of Taizhou and Shepan Island in Zhejiang province

laboratory tests of saturated water absorptivity of dry rock block and slaking test are conducted; and GSD of the dry collapsed scraps

slake durability index and their relationship with expansibility derived from saturated water absorptivity of the swelling rock are analyzed. Results show that the effective grain size

grain sizes of the particle group with the maximum content and slake durability index are inversely correlated with the level of expansibility of the swelling rock. It is concluded that GSD of dry collapsed scraps of swelling rock can approximately act as an indicator for the level of expansibility.