As the data for free shrinkage alone was found to be insufficient to predict the risk of early- age shrinkage cracking of restrained concrete, we developed a new technique to characterize the cracking phenomenon based on innovated ring-type specimen tests.…
As the data for free shrinkage alone was found to be insufficient to predict the risk of early- age shrinkage cracking of restrained concrete, we developed a new technique to characterize the cracking phenomenon based on innovated ring-type specimen tests. The ring test consists of a concrete annulus that is cast around a hollow brass cylinder. As the mortar hydrates and dries, shrinkage is prevented by the ring resulting in the development of tensile stresses in concrete. With this experimental device, we were able to predict the risk of cracking in mortars. For this purpose two kinds of tests were defined: the semi-rigid ring, which allows a partial and constant restraint and the full-compensation system, using a pressurized cylinder around which the mortar was cast. Thus, we were able to follow the growth of internal properties of the material during aging such as, free shrinkage, restrained tensile stresses and visco-elastic response, which will provide precious information for future numerical implantation.