Slakeability and swellability characterizations of Subang claystone of West Java, Indonesia

The Indonesian government recently launched several strategic construction projects in the West Java Province involving the construction of the Kertajati international airport, Jatigede large dam, and Cisumdawu toll road, and upgrading many existing roads and the construction of new ones. It should be noted that some of these projects lie on clay-bearing sedimentary rocks known as Subang claystone, in which many cuts and fills must be constructed. It is already widely known that Subang claystone has unfavorable engineering characteristics regarding slakeability and swellability behaviors, so this research will be helpful to give engineering considerations for all those strategic construction projects. This research will be focused on the analyses of slakeability and swellability characterizations utilizing slake-durability and unconfined swelling tests, as well as consistency analyses of the claystone as standardized by the International Society for Rock Mechanics, Suggested Methods. Field observation and rock samples conducted in the Sumedang area for the claystone is the most abundant rock type. Widespread outcrops, numerous excavations, and road cuts have provided excellent samples. The test results indicated that the claystone could be classified as a very low-durability rock, with Id2 ranging from 5.82% to 26.80%. It means that Subang claystone has a high slakeability characteristic. The claystone also showed a high swellability characteristic with volumetric swelling strain reaching up to 29.6% and medium to high plasticity indexes ranging from 30.9% to 35.2%. There was a good correlation between the claystone’s slakeability, swellability, and consistency.