Time-Dependent Flexural Behaviour of SFRSCC Elements

This work presents and discusses the long-term behaviour of pre-cracked steel fibre reinforced self-compacting concrete (SFRSCC) laminar structures of relatively small thickness. One hundred and twelve prismatic specimens were extracted from a SFRSCC panel. These specimens were notched with different orientations regarding to the expected SFRSCC flow direction, and were tested under four-point flexural sustained loading conditions. The influence of the following parameters on the creep behaviour was studied: initial crack opening level (0.3 and 0.5 mm), applied stress level, fibre orientation/dispersion, and distance from the casting point. Moreover, to evaluate the effect of the long-term residual crack opening on the flexural post-cracking strength, as well as on the secondary stiffness, a series of instantaneous monotonic and cyclic tests were carried out, and the corresponding force vs crack tip opening displacement (F-CTOD) curves were compared to the ones obtained by assembling the F-CTOD curves determined in the pre-crack monotonic tests, creep tests and post-creep monotonic tests. Finally, based on the results obtained from the creep tests, an equation was proposed to predict the creep coefficient for the developed SFRSCC.