Home Engineering Creep Behaviour in Cracked Sections of Fibre Reinforced Concrete: Proceedings of the International RILEM Workshop FRC-CREEP 2016
Effect of Load, Temperature and Humidity
Studies have shown that the load level (i.e., the ratio of the sustained load applied to the specimen to that required for precracking the specimen) has an important effect on flexural creep response of cracked FRC. It was found that an increase in the load ratio always leads to higher creep strains . Zerbino and Barragan  observed that the precrack width and sustained load level are interrelated; a stable creep response is obtained at lower precrack widths, under higher load ratios or at wider cracks, under lower load levels.
Temperature also has a significant influence on the long term behaviour of FRC. The effects of moderate temperatures (20 to 40 °C) and elevated temperatures (about 60 °C) on the long term behaviour have been studied by some researchers [13, 15, 16]. Increase in temperature has an effect on creep performance of steel and polymer fibre reinforced concrete, with higher creep deformation at higher temperature. It was observed that at room temperature and at elevated temperature polymeric fibre reinforced concrete (PFRC) experienced larger creep deformations than steel fibre reinforced concrete (SFRC), especially for larger initial crack widths
(> 1.5 mm). However for smaller crack openings, the effect of temperature variation is negligible. The increased creep deformation of steel FRC at moderate to elevated temperatures might be caused by modifications in the long term behaviour of fibre-concrete bond while the creep failure of synthetic FRC might be due to creep deformations of the fibres themselves. Under wetting and drying cycles, the effect of temperature seems to be further aggravated . In general, the ambient humidity also has an effect on the creep of cracked FRC, with deflections increasing with a drier environment, leading to more creep deformation and earlier creep failure.
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