One of the Possible Experimental Way to Determine the Tangent Adhesion Between the Concrete (Mortar) and Stone by Testing the Samples Under Torsion
This article presents the results of experimental tests to determine the tangent adhesion between concrete (mortar) and tuff stone. A special device was designed to allow us to determine the tangent adhesion strength for the samples tested under pure torsion. The test results for samples with square cross-section tested under pure torsion on the designed device are presented. The test results for eight-shape samples, which were made from the same concrete mixtures and tested for fracture (normal adhesion), were also presented as a comparison. Testing the samples under pure torsion allowed us to define the ratio of tangent and normal adhesion strengths of lightweight concrete and tuff stone. It ranges from 2.0 to 4.0, which is considerably higher than the one presented in certain publications (it ranges from 1.5 to 2.5). Presumably this variation may be explained by the different techniques that were used to define the value of tangent adhesion of concrete (mortar) and tuff stone.