Size Effect in flexural Strength Test on Dimension Stones

The flexural strength test under a concentrated load, as foreseen required for CE marking, can be used to assess the mechanical resistance of dimension stone and, if performed after accelerating tests, their durability. Often the producers, and above all the importers of slabs, who are in charge of the application of the CE marking, are not able to test their products in compliance with the standardized test method due to the required thickness of specimen, which should be of at least 25 mm. This problem has led to this research, which is devoted to the detection of a possible variation of flexural strength linked to a variation in the shape and/or dimensions of the test specimens, (size effect). The experimental data of 15 different types of rock stone have been analyzed considering the specimen thickness. From the obtained results it is possible to assert that, the value variation for different thickness is negligible, considering the high dispersion of the results.