Creep and failure prediction of Diestian ferruginous sandstone: Modelling and repair options

Diestian ferruginous sandstone is a brown–red, porous sandstone which has been used for the construction of numerous monumental buildings in Belgium. Urged by a number of collapses of monuments, a research program was set up which aims at characterising the sandstone’s behaviour under monotonic and sustained loading. It was found that the sandstone has a low compressive strength with a large scatter on its mechanical properties and is very sensitive to time-dependent mechanical deterioration. A viscoelastic model with damage is used to model the sandstone’s creep behaviour. The model takes into account damage accumulation at low stress levels. The model is calibrated on the results of experimental creep tests and used to simulate the time-dependent deformations of a collapsed bell tower. Finally, future prospects for the use of this sandstone and repair options are discussed.