Experimental approach to investigate creep-damage bilateral effects in concrete at early age

The concrete structures are under heavy loads once they are set up. The effect of this early loading particularly in terms of creep deformations could be very significant. In order to evaluate the effect of these deformations on the cracking risk of concrete, many studies on early-age creep have been conducted in the last decades. These studies concern mainly tension and compression loadings. However, few studies have been conducted under bending, even though this loading is the most representative for structures. This paper is focused to improve the understanding of the historical loading effect on the concrete residual behaviour. A series of flexural creep tests were performed at early ages on non-damaged beams with a constant and a stepwise increasing creep loads. In order to better understand the interaction between creep and damage, series of flexural creep tests were also performed at early ages on partially damaged beams. The test results have shown a drop of Young's modulus and residual strength after creep loadings in partially damaged beams. It implies the development of a state of weakness in beams subjected to an increasing creep load.