Creep behaviour of cracked steel fibre reinforced self-compacting concrete: from micro-mechanics to composite behaviour

Abstract

This work presents the results of an extensive experimental program that aims to study the long-term behaviour of cracked steel fibre reinforced self-compacting concrete (SFRSCC). At the micro-level, a series of single fibre pull-out creep tests were performed, and the fibre slip was monitored as a function of time. The influence of fibre orientation angle (0, 30 and 60 degrees), as well as pre-imposed fibre slip levels 0.3 and 0.5 mm on the creep behaviour was investigated. At the composite level, prismatic specimens were extracted from a SFRSCC panel, having in consideration the concrete flow direction. The specimens were pre-cracked up to 0.3 and 0.5 mm and subjected to a sustained flexural loading. In this stage, the influence of the pre-crack level and fibre orientation on the long-term crack opening was appraised. Furthermore, instantaneous fibre pull-out tests and bending tests were performed on undamaged specimens to quantify the effects of the creep phenomenon. It was found that a higher damage level in the specimens accelerated the creep rate. Moreover, the creep performance of the SFRSCC was influenced by the fibre orientation. Finally, the assembled creep curves did not differ considerably from the instantaneous behaviours for the adopted pre-damaged levels.