Prediction of long-term slake durability of clay-bearing rocks

A research program was conducted on different clay-bearing rocks selected from the Ilam, Sarpol-e Zahab and Tajarak regions (Iran) to predict their slaking characteristics. The new durability apparatus (nested mesh drums) separates disintegrated particles varying from > 25.4 to < 2 mm as the drums were rotated. On the basis of the particle size distribution, the disintegration ratio (DR) was used to evaluate the rock durability. A concept was proposed to describe the rock slaking characteristics under the slake durability test cycles, by using the difference in the DR values between the adjacent (?DR) and backward (N*) cycles. This allows the estimation of the rock durability as it is subjected to a larger number of test cycles, and hence the prediction of the effects of weathering processes. This prediction provides an effective approach when data are limited or inaccessible. Therefore, a new classification system is introduced for rock durability assessment. The test results show that the Gurpi-limey marls (G-2, G-3) and the Pabdeh-marly limestone (P-3) are classified as moderate to high durability rocks