The Slake Durability of Argillaceous and Non-argillaceous Rocks: Insights From Effects of the Wetting–Drying and Rock Lumps Abrasion

The slake durability test device was primarily designed for argillaceous rocks (clay-bearing) such as shale, claystone mudstone, and marl by Franklin and Chandra (Franklin JA, Chandra R (1972) The slake-durability test. Int J Rock Mech Min Sci 9:325–341). Later, the International Society for Rock Mechanics standardized the test method (ISRM (2007) The complete ISRM suggested methods for rock characterization, testing, and monitoring, 1974–2006. In: Ulusay R, Hudson JA, compilation arranged by the ISRM Turkish national group, Ankara, Turkey). The slake durability test is conducted to assess the durability offered by argillaceous rocks to degradation (slaking) when subjected to wetting–drying cycles (WD cycles). However, in previous decades two, various researchers also have used this test to assess non-argillaceous rocks. In this paper, the effects of the WD cycles and rock lumps abrasion (RLA) on the degradation of argillaceous and non-argillaceous rocks during the slake durability test are investigated. To this end, some marls and limestones (as argillaceous and non-argillaceous samples, respectively) were collected from rock trenches along roads in Lorestan province, west of Iran. The mineralogical studies were performed by microscopic thin sections and X-ray diffraction analyses (XRD). Also, physico-mechanical tests, including porosity (n) and point load index (PLI), and slake durability tests up to 15 cycles were carried out to characterize the samples. Results indicated that the degradation of argillaceous samples [assessed using slake durability index (SDI)] during the slake durability test was remarkably affected by WD cycles. Besides, the RLA showed less effect on the degradation of these samples. WD cycles had a preventative role in the degradation of the non-argillaceous samples, and only the RLA was responsible for the degradation of these sample types. The findings show that clay minerals in argillaceous samples make them highly susceptible to degradation by WD cycles. Moreover, the absence of these minerals in non-argillaceous samples has caused their degradation to be independent of the WD cycles. According to simple regression analyses, there is a good correlation between the degradation of the argillaceous samples with their saturated-to-dry PLI ratio (PLI_r). However, no significant correlation existed between degradation and PLI_r of the non-argillaceous samples. Overall, the PLI_r can be considered a low-cost, rapid, and precise indicator to assess the degradation of the argillaceous samples during the slake durability test.