Concrete Shear Strength Parameters Compared to Other Laboratory Determined Properties

Examination of a large sample of direct shear test results on concrete specimens offers a unique insight into material properties for use in appraisal level design or a screening level evaluation of an existing structure. Several factors, such as cost, lack of suitable cores for testing, or historical data sets that do not contain direct shear test results, often make inference of direct shear strength, in both breaking and sliding friction, via correlation from other properties desirable. In order to investigate a possible correlation between the results of unconfined compressive strength, direct tensile and splitting tensile tests, and shear strength, the results of numerous tests conducted on core samples from various projects were analyzed. Results of the study confirmed commonly used relationships between compressive and tensile strength parameters. No direct correlation between compressive/tensile strength parameters was noted. The study did note that the cohesion intercept for break-bond testing can be roughly approximated using splitting tensile or uniaxial compressive testing results, and that the Mohr-Coulomb friction angle for break-bond testing is similar to that found during sliding shear testing.