Assessing the durability of mudrocks using the modified jar slake index test

Abstract

As exposure to weathering processes or other changes in moisture content can be the cause of troublesome breakdown of many mudrocks, it is essential to have reliable means of predicting this behaviour. Although the ISRM slake durability test is the standard test used to distinguish between durable and non-durable mudrocks, the test does not always identify problematic materials. The dynamic nature of the test and the use of an arbitrary 2 mm drum mesh size are particular short falls. The test is too aggressive to characterize properly the behaviour of low durability mudrocks and slaking of samples to a fragment size greater than 2 mm is not measured. This paper reviews the various tests that have been used for predicting slaking potential. Comparative durability testing of 49 selected UK mudrocks ranging in age from Cambrian slates to Carboniferous Coal Measures is described. An evaluation of the performance of these materials in the one- and three-cycle ISRM slake durability test confirms the greater value of the latter. The modified jar slake test was found to be a suitably simple and accurate means of determining the durability of these mudrocks. Comparisons with the results of natural slaking trials confirm that the modified jar slake test presents a more detailed evaluation of the slaking potential of samples. In practice it is anticipated that the described test procedure will be used to provide data that would augment sample evaluation based on the ISRM slake durability test.

Study on the physical disintegration characteristics of Subang claystone subjected to a modified slaking index test

“…Moreover, the test also employs a tumbling factor, which generally does not exist in the field. Meanwhile, it is surprising that there is no specified testing procedure for a static slaking test even though a number of experiments have been carried out, such as the ones performed by Morgenstern and Eigenbrod (1974), Wood andDeo (1975), Venter (1981), Ichinose and Matsui (1989), Santi (1998), Czerewko and Cripps (2001) and Sadisun et al (2002a). In general, the static slaking tests provide simple and reliable tests when the standard slake durability test is impermissible, particularly for medium to very weak rock materials (Sadisun et al, 2002a).…”

Multivariate statistical approach to re-evaluate the slake durability index test (ASTM 4644–08)

“…The main problem with the slake durability index test according to various researchers (Czerewko and Cripps, 2001;Erguler and Shakoor, 2009and Richardson and Long, 1987, Moon and Beattie, 1995 is that the test is not efficient in differentiating durable from non-durable mudrocks ( Figure 2). This is mainly because of the 2 mm mesh size which may retain a large portion of slaked material even for non-durable rocks…”

Problematic Soils: Proceedings of the Symposium held at the Nottingham Trent University on 8 November 2001

“…It has been shown by Czerewko & Cripps (2001) that the standard slake durability test lacks sensitivity when it is used to distinguish between durable and non-durable mudrocks. This is due to the inherent bias possessed by the equipment used for the test, as an arbitrary 2mm mesh size is used to distinguish between slaked and non-slaked material.…”

“…It was found that the modified jar slake index (Czerewko & Cripps, 2001) provides an additional means of textural classification since the test monitors the extent of microfracture development. Fracture distribution counts were carried out on sections cut perpendicular and parallel to bedding.…”