A Comprehensive Study on the Effect of Fibers and Loading on Flexural Creep of SFRC

This paper reports the results of a research whose aim was to study how the following variables affect the way SFRC behaves in the postcrack region when under sustained flexural loads: fibers length and slenderness, fibers content, maximum aggregate size, and the load applied. A new methodology based on a test setup developed by the authors has been followed in this research, where notched prismatic 150x150x600 mm specimens are subject to a flexural creep test which follows the four-point bending scheme. Several parameters have been measured: initial crack width, crack width at 90 days, and crack opening rates and creep coefficients at 14, 30, and 90 days. The effect of the variation of the variables considered on these parameters has been evaluated by means of statistical inference based on multiple linear regression models. Results clearly show that varying fiber slenderness leads to important differences regarding concrete’s flexural creep behaviour. The mere fact of adding fibers is good from the point of view of controlling creep strain, though variation in fiber content between 40 kg/m3 and 70 kg/m3 has turned out to be not so important when compared to the effect that varying the load applied has on many of the parameters analysed.