Effects of water intrusion on thermal conductivity and durability of carbonaceous rocks

Abstract

This study aimed to investigate the role of water intrusion on thermal conduction and durability of three types of carbonaceous rock with different mineralogical components. The soaking method was selected to simulate water intrusion, and the respective evolutions of thermal conductivity k and slake durability index Id2 during soaking period were assessed. Scanning electron microscopy was conducted to explore the mechanism controlling these revolutions. The results revealed that the magnitude of moisture content and density of carbonaceous rocks at their natural state was clearly correlated to the content of illite mineral. Water intrusion was beneficial to the thermal conduction of carbonaceous rocks, where thermal conductivity increased with an increase in soaking time and exhibited a moderate increment after 8 days of soaking. Slake durability index Id2 was sharply decreased as soaking progressed and reached a low level after soaking. This deterioration in durability was mainly attributed to the absorption of free water, which in turn yields the anisotropic expansion of specific minerals. An unstable structure with more pores and new morphology minerals were identified in carbonaceous rocks at the completion of soaking procedure. An empirical relationship was developed successfully for predicting slake durability index using thermal conductivity.