Effect of initial crack opening on flexural creep behavior of frc specimens

LLANO TORRE, AITOR; SERNA ROS, P.; ZERBINO, R.; MARTI VARGAS, R.

Vancouver

Simposio; 9th RILEM International Symposium on Fiber Reinforced Concrete, befib 2016; 2016

RILEM

Many efforts have been recently made to evaluate the different methodologies and to analyze the influence of factors and parameters affecting flexural creep tests of Fiber Reinforced Concrete (FRC) in cracked state. The creep test procedure includes a pre-cracking phase in order to create certain damage on the concrete specimens to be tested. This initial damage -or crack opening- may be decisive in subsequent test results. For this reason, this study aims to evaluate the effect of different initial crack openings on flexural creep tests carried out with prismatic specimens of FRC. To this end, two concrete batches reinforced with fibers have been cast; one batch with steel fibers and the other one with synthetic fibers. For each fiber material type, up to 9 prismatic specimens 150x150x600mm were cast: 3 specimens for characterization purpose and 6 specimens for flexural creep test. The specimens for creep analyses have been tested in a similar way following a flexural test methodology with different initial crack openings at the pre-cracking phase. The considered initial crack opening ranges from 0.2 to 2 mm, which represents different levels of damage of a structure. The load level applied in each specimen has been 45% of mean of fR1 values obtained in all pre-cracking tests. The test results show that the initial crack opening CMODp of the specimen before creep tests has little influence on Crack Opening Rates for both FRC batches.