Effect of beam width on the creep behaviour of cracked fibre reinforced concrete

Abstract

Many efforts have been made to develop a creep testing procedure for fibre concrete in cracked state. Among several proposals the use of a bending test seems a promissory alternative. The “creep testing procedure” includes a pre-cracking process up to some established crack width, the creep test itself applying permanent loads and finally, a bending test to evaluate the residual strength properties after creep. This paper compares the results of creep tests performed on beams of different widths (50, 100 and 150 mm). The use of thin fibre reinforced concrete specimens should be of interest for applications such as the reparation of concrete structures or the protection of elements exposed to extreme actions. A conventional fibre concrete incorporating 40 kg/m3 of hooked-end steel fibres with a 51.3 MPa compressive strength, class 4a, was used. The specimens were pre-cracked up to 0.5 mm and the sustained bending stress was equal to 60% of the stress fR1 of each prism. The results show that the specimen width has a minor effect on the results of creep tests in cracked state but the variability increases when the width decreases.