TOUGHNESS MEASUREMENTS ON STEEL FIBRE-REINFORCED HIGH STRENGTH CONCRETE

Abstract The paper reports on strength and toughness measurements on a range of normal and high strength concrete mixes, with and without steel fibre reinforcement. Cube strength, modulus of rupture, cylinder splitting and torsional-tension test results are reported together with toughness measurements determined via two fracture-type test specimens (standard RILEM three-point notched beams in flexure and eccentrically loaded notched cubes). In the toughness tests, crack mouth opening displacement (CMOD) was measured and used in a closed loop testing mode to achieve complete load/displacement curves. Good correlation was observed in the strength tests and the two toughness tests showed similar load-CMOD curves and toughness indices. However, traditional toughness indices are unsatisfactory with load-CMOD tests, and further work is necessary to define acceptable toughness measurements, which may also have to account for size effects. The effect of steel fibre reinforcement on high strength (up to 120 N mm 2 ) and normal strength concrete is similar.