Effect of Rehydration on Properties of Cement-Fly Ash System

In this article, the effects of rehydration on the performance of cement-fly ash systems were investigated by conducting rehydration tests of cement-fly ash systems under low water-binder ratio conditions, testing the chemically bound water content, expansion rate, and strength of specimens at different rehydration ages, combined with the alkalinity of pore solution, pore structure and micromorphology. The results show that the lower the water-binder ratio is, the higher the water content of the rehydration combination in the early stage is, but the lower it is in the later stage. The higher the fly ash content is, the lower the rehydration degree of the system will be. An alkaline environment is more effective in enhancing rehydration. The expansion rate of the specimen increases with the decrease of the water-binder ratio. The strength of the specimens with the water-binder ratio of 0.18 showed an alternating trend of increasing and decreasing with the increase of rehydration age, indicating that rehydration is a simultaneous process of repair and damage.