Abstract
Fluorescence microscopic examinations were conducted to identify damages induced by restraining autogenous shrinkage. Characteristics of fluorescent areas and their correspondence to autogenous shrinkage behavior of high strength concretes were discussed. Silica fume concrete exhibited a greater creep potential when loaded at very early ages. The microstructure in sealed concretes was porous, especially in the interfacial regions around aggregate particles. In addition, sealed silica fume concretes contained many Hadley grains. These features of microstructure were not observed in water ponded concretes. The detected fluorescent areas may be defects caused by self-desiccation and autogenous shrinkage. The flaws had little effects on the development of strength. However, the presence of thin gaps around remnant cement particles may increase creep deformation to relieve internal stresses.
