Round-robin analysis of the RILEM TC 162-TDF uni-axial tensile test: Part 2

Plain and steel fibre reinforced concrete cylinders were tested uni-axially in tension under closed-looped conditions in a round robin test programme. During the test, three deformation readings around the notched plane were measured. It was found that during the course of the test, rotations were occurring and thus a fibre counting exercise was initiated. This was to investigate the influence of fibre distribution within the cylinder specimens on the observed rotations of the specimens. The results of the investigation could not detect any strong correlation between the fibre distribution and the observed rotations and a more likely source for the variations observed is the boundary conditions of the tests. Significant variations were found in the number of fibres with coefficients of variation in the range of 30% to 50%. Additionally, it was found that toughness is approximately linearly related to the number of fibres in the fracture surface up to a certain limiting value where the toughness appears to plateau in relation to the mumber of fibres.