Experiences from 14 Years of Creep Testing of Steel and Polymer Fiber Reinforced Concrete

Abstract

This paper presents an overview of different creep setups, applied in the Bekaert concrete laboratory since 2002. The tests demonstrate the long term behaviour of cracked fibre reinforced concrete under sustained load, investigating statically determinate and indeterminate test setups, fibre type (steel and polymer macro fibres) and fibre dosage. The duration of the creep tests ranges from less than 1 to 14 years. The following observations were made: (1) Specimens reinforced with polymer macro fibres show a large deformation increase under sustained load, while specimens reinforced with steel fibres withstand. (2) After more than 2 years of testing, no difference in behaviour could be observed between steel fibres with different anchorage and corresponding material characteristics. (3) Increased deformation during the pre-cracking stage, along with increased sustained load has been found to have a higher impact for polymer macro fibres than steel fibres. All setups have been tailored to specific applications and thus vary in size, applied load and pre-cracking deformation. The same holds for setups used by other research groups so that it is difficult to compare results. Based on the experience built up during the course of the programs, proposals for an improved test setup are made.