Indirect tensile strength tests
A cylindrical specimen is loaded diametrically across the circular cross section. The loading causes a tensile deformation perpendicular to the loading direction, which yields a tensile failure. By registering the ultimate load and by knowing the dimensions of the specimen, the indirect tensile strength of the material can be computed. Below is a figure showing the load fixture and a principal picture of the loading.
A load situation for an indirect tensile strength test
A summary of results from 33 tested specimens from a borehole is shown in the figure below. The specimens are loaded along and across the direction of the foliation and the results display a material anisotropy on the depth levels at 160 and 815 meters.
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| Specimens loading to failure along (left) and across (right) the direction of the foliation. |
Summary of results from indirect tensile strength tests from a borehole with an anisotropic material.
The results and pictures are taken from:
Jacobsson, L. Forsmark site investigation, Drill hole KFM04A, Indirect tensile strength test. SKB-P04-174, Svensk Kärnbränslehantering AB, 2004.
Example of standards
ASTM D3967-95a, 1996, Standard test method for splitting tensile strength of rock core specimens