ABSTRACT

Some analytical solutions about indirect (splitting) tensile strength test disk stress distribution, valid loading and splitting forms of approaches are discussed in this work. Indirect tensile strengths of 10 different specimen types (9 different rock types and 1 concrete mix) were tested with standart jaw and flat platen (jawless) loading. Flat platen loading has been investigated as an alternative for standart jaw. And, it was widely used until standart jaw became popular. Mode of failures were sighted according to specimen types and loading types. Many of standart jaw loaded disks didn't fail with ideal splitting. Standart jaw has significant contact area, hence load type can't be considered as line load. In this situation, suggested standart Brazilian strength test formula isn't suitable. Nondefinite contact angle restricts to use some analytical approaches that is suitable to use for standart jaw. Flat platen loading supplies ideal splitting on the vertical diameter of disk. However, flat platen caused to occur crack initiation in compressive zone of some disks. This is an important reason for invalidity of test, because cracking must be started by tensile stresses. Thoughness is very critical parameter for representing direct tensile strength test results. For general of rocks, standart jaw has higher fracture toughness and flat platen loading has lower fracture thoughness than standart direct tensile strength test. As results of recent works, neither standart jaws nor flat platen loading represents direct tensile strength, completely.

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