Behavior of a Mass Concrete Affected by ASR: Evolution and Anisotropy of Expansion, Damage and Mechanical Properties

Mass concrete specimens, consisting of concrete cores drilled in various directions from large blocks cast in the laboratory, were stored under conditions favorable to the development of ASR (38 ℃; 100% R.H.). The test specimens were obtained by drilling in either the vertical or horizontal direction of the blocks, in view of highlighting a potential influence of the presence of flat and elongated coarse aggregate particles, which may tend to orient preferentially in the fresh concrete during placement. In groups of six, the specimens were removed from their conditioning environment upon reaching selected levels of expansion to perform compressive strength tests, Stiffness Damage Tests (SDT), and petrographic examinations. As expected, the expansion data show a strong anisotropic character. The evolution of the SDT output parameters was found to be isotropic for expansion levels below 0.20%, and anisotropic above this threshold.