RILEM Standard: testing methods for determination of the double-K criterion for crack propagation in concrete using wedge-splitting tests and three-point bending beam tests, recommendation of RILEM TC265-TDK

In this recommendation, standard testing methods for determination of the double-K criterion for Mode I crack propagation in concrete using wedge-splitting tests and three-point bending beam tests are specified for the fracture parameters of the initial cracking toughness K-Ic(ini) and the unstable fracture toughness K-Ic(un). Along with the recommendation of the standard testing methods, the theoretical background of the double-K criterion, the calculation methods and the results of round-robin testing for determining the double-K fracture parameters are presented in technical reports [1, 2]. The recommendation of the standard testing methods includes geometry for specimens, fabrication of specimens, testing machine, load transmission system and supports, measuring instruments, determination of initial cracking load P-ini, determination of measured maximum load P-max and initial compliance c(i), calculation methods for wedge-splitting test and three-point bending beam test, as well as the testing results and testing report forms. According to these methods, the measured fracture parameters of double-K criterion can be used to describe the onset of cracking, and the onset of unstable cracking or failure for predicting crack initiation, structure failure and crack stability in concrete structures.

Automated summary

This recommendation specifies standard testing methods for determining the double-K criterion for Mode I crack propagation in concrete, including geometry for specimens, fabrication of specimens, testing machine, load transmission system, and supports, measuring instruments, determination of initial cracking load P-ini, determination of measured maximum load P-max and initial compliance c(i), calculation methods for wedge-splitting test and three-point bending beam test, as well as the testing results and testing report forms. By using these methods, the measured fracture parameters of double-K criterion can describe the onset of cracking, unstable cracking, and failure in concrete structures.