A NEW ANALYSIS OF THE RESTRAINED RING SHRINKAGE TEST

At early-age in massive concrete structures, cracking may occur during hardening. Indeed, hydration is an exothermic chemical reaction (temperature in concrete may overcome 60 degrees C). Therefore, if autogenous and thermal strains are restrained, compressive stresses and then traction stresses rise, which can exceed the concrete strength. This cracking may increase significantly the concrete wall permeability. The restrained shrinkage ring is a good method to determine the behaviour of concrete (delayed strain and cracking) due to the autogenous and drying shrinkage. In this test, several coupled phenomena occur simultaneously. Moreover, direct strain measurements in concrete are difficult to perform. Therefore, a good analysis of the retrained ring shrinkage test is needed and two methods are here compared. The first one is a 113 analytical method which has been previously developed by [Monge 2003]. The second one is based on an axisymetric finite element calculation (Cast3M code, developed by the French atomic energy commission) with the use of thermo-chemo-elastic-damage model [Benboudjema and Torrenti 2008]. We also compared the finite element calculation and the analytical analysis developed by [Weiss 2001]. Since several phenomena occur simultaneously, the objective is to highlight which material parameters have a significant influence on the results of finite element calculations.