ABSTRACT
Since concrete is generally weak and brittle in tension compared to its capacity in compression, steel fibre reinforcing is a practical means to improve the tensile performance as well as the tensile post-cracking behaviour of this cementitious material. Question still remains on a relevant evaluation of these properties in the current practice. This paper describes experimental results which have been obtained in our laboratory for Mode I fracture of steel fibre reinforced concrete, using special test methods for evaluating the fracture toughness, ductility and energy absorption capacity of the cementitious composite. The fracture toughness has been evaluated by various toughness indices reported in literature which are easily determined from the load-displacement curve of direct tension tests. The tensile cracking process has been detected by analysing the signal evolution of ultrasonic waves propagating through the specimen which is subjected to increasing static loads. A nonlinear analyser based on a multidimensional Fourier transform permits to separate the nonlinear part from the linear one of the response.
