Epoxy-bonded rebar is commonly used to support the roof of an underground potash mine. The rebar is often loaded in tension, but in certain circumstances, the potash can load the rebar in shear or by a combination of tension and shearing. Rebar failure due to tension has been studied previously and is well understood. A laboratory test procedure has been developed to help quantify rebar shear behaviour. The rebar is tested by bonding it in three segments of steel pipe and applying a lateral load to the centre segment. These tests isolate the rebar-epoxy interaction from the highly variable effect of the surrounding potash. The test method also allows for an easy and controlled comparison of different sizes of rebar, grades of rebar steel, and aperture between the pipe sections; all of which can significantly affect the behaviour of rebar in shear.The data gathered during each test includes the load and displacement. However, distributed optical strain sensing is also being used, which allows for strain measurements at 0.5 mm resolution along the length of the rebar. This technology allows for detailed insight into rebar behaviour. The International Minerals Innovation Institute (IMII), PotashCorp, The Mosaic Company, Agrium Inc., as well as Natural Sciences and Engineering Research Council of Canada (NSERC) are sponsoring this research project.
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