Experimental research on uniaxial tensile creep behaviour of pre-cracked fibre reinforced concrete

Fibers play an important role in the post-crack performance of fiber reinforced concrete (FRC). Most of the research has been out either on creep behaviour of uncracked FRC specimens or compressive creep behaviour. Literature on tensile creep behaviour of cracked steel fiber reinforced concrete (SFRC) is very limited by now. In order to investigate the tensile creep behaviour of cracked SFRC, a uni-axial tensile creep test is performed. A creep frame with a lever system is firstly developed for the tensile loading. The test cylinder specimens are pre-cracked up to a crack width of 0.05mm. Then the pre-cracked specimen is loaded at different stress level: 30% and 60% of their tensile strength respectively. The whole test setup is placed in an environmental chamber with constant relative humidity 60% and a temperature of 20 degrees. During the test both the total tensile creep deformation of the specimen and the creep deformation at the place of the precracked section is monitored using LVDT. Additionally, in order to further investigate the contribution of viscoelastic and viscoplastic properties of SFRC respectively, both the basic creep and drying creep are measured, the tensile creep is measured continuously for 3 months.