Creep in pre-cracked fiber reinforced cementitious composites has become an important topic of study recently. This is due to the fact that under serviceability limit state the concrete may crack and its stability will depend on the fiber and fiber-matrix…
Creep in pre-cracked fiber reinforced cementitious composites has become an important topic of study recently. This is due to the fact that under serviceability limit state the concrete may crack and its stability will depend on the fiber and fiber-matrix interface properties. The time dependent behaviour of FRC and long term stability of cracks under sustained bending loads are still poorly understood. This work seeks to explore the use of steel and PP fibers in order to define their influence on creep, by analysing the crack opening displacement rate in FRC specimens. For the creep tests, the specimens were pre-cracked to 0.5 mm, and then tested under constant load during 45 days. The constant load applied was calculated based on the residual stress found for 0.5 mm of crack opening, which corresponds to 30% of its residual load. In order to better understand the related mechanisms, creep tests were also carried on a fiber pullout configuration. Analysing the creep tests results, it was verified that the COD rate is an interesting tool to evaluate the long-term behaviour of the cracked FRC and to define a stability criterion. In addition, it was found that concrete incorporating macro synthetic fibers presents higher creep deformations and higher creep rate than concrete reinforced with steel fibers. This can be explained by the different fiber-matrix bond characteristics. Finally, the residual properties of creep tested specimens were determined by monotonic flexural tests performed in the FRC specimens after the creep tests.