Exploitation of inherited weakness in fire-damaged building sandstone: the 'fatiguing' of 'shocked' stone

Results illustrate that the post-fire deterioration of sandstone is strongly conditioned by fracture networks and soot cover inherited from the fire. The exploitation of fractures can lead to spalling during salt weathering cycles - this takes place as granular dissagregation steadily widens cracks and salts concentrate and crystallise in areas of inherited weakness. Soot cover can have a profound effect on subsequent performance. It reduces surface permeability and can be hydrophobic in character, limiting salt ingress and suppressing decay in the short term. However, as salt crystals concentrate under the soot crust, detachment of this layer can occur, exposing fire-damaged stone beneath. Understanding the subsequent exploitation of stone exposed to fire damage by background environmental factors (for example, salt weathering/temperature cycling) is key to the post-fire management of stone decay.