Temporal peculiarities of brittle fracture of rocks and concrete
When we want to compare the strength of two materials, we compare the table values of quasistaticstrength. However results of some experiments show that the strength ratio of the materials can changewith increase in rate of loading. Such "substitution effect" of material strength at different strain rates is studiedin this paper. It is shown that one material can have a lower dynamic strength for a higher static strengthcompared to the other material. Tests of two different materials, tests of mortar and concrete, and tests ofconcrete with different water content are considered. It is shown that load-carrying capacity of materials and thesubstitution effect of material strength in a wide range of loading rates can be predicted by the incubation timecriterion.