Time-delayed rupture of stones under low tensile and bending stress states

The advancements of research dealing with the time-delayed behaviour of building stones are presented. In preceding papers, the results of long-term tensile and bending tests conducted on one type of Carrara marble, two sandstones, and one limestone were reported. A composite phenomenological model was also defined which permitted to suitably reproduce the recorded responses. in this paper, the tests carried out by applying the minimum percentile rate of the fracture loads (equal to 35%), having in the meantime arrived at completion, are described. The outcomes of these tests confirm the basic features of the creep response observed in the previous sections of the experimental programme. By updating the experimental time-to-rupture curves with reference to the new data, an asymptotic trend towards the elastic limit values of the materials is noted. A modified version of the time-to-rupture law associated with the tertiary branch of the phenomenological model is supplied, which allows to further improve the relevant prediction potentialities.