Assessment of factors controlling the slaking behaviour of rocks from the Rhenodanubian Flysch Zone, Austria, using mineralogical-geomechanical laboratory tests

The claystones, siltstones, sandstones and marly limestones of the Rhenodanubian Flysch Zone of Austria are classified as weak/soft rocks due to their behaviour when exposed to water or subject to mechanical load. The flysch rocks were investigated with respect to their slaking durability, uniaxial compressive strength, abrasivity and mineralogical composition to assess the influencing factors affecting material behaviour and correlations of different mineralogical-petrographical and rock mechanical parameters are elaborated. It is shown that the presence of carbonate minerals can favour the slaking resistance, while sheet silicates seem to affect slaking only after many testing cycles. The rocks exhibit a wide range of slaking durability and low to moderate strength, with low abrasivity. The correlations of engineering rock properties of these soft rocks are weaker compared to those of grain bound crystalline rocks and quartz imposes less influence on durability, abrasivity and strength making their characterization and classification challenging.