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Description: In order to provide a better understanding of the DEF phenomenon, the present study investigated mortar systems made with various mixing and curing parameters for detailed changes in pore solution chemistry and solid phase development, while corresponding changes in physical properties were also closely monitored. This holistic approach enabled the development of a correlation between the chemical and physical changes which occur in the DEF-affected mortars. The present study revealed that relationships exist between the physical properties and expansive behavior. The normal aging process of the cementitious systems involves dissolution of uniformly distributed fine ettringite crystals within the hardened cement paste and subsequent recrystallization as innocuous crystals in the largest accessible spaces. This process, known as Ostwald ripening, facilitates relaxation of any expansive pressure developed within the paste. Ostwald ripening is impeded in a well-compacted, dense microstructure containing few flaws due to the low diffusion rate of the system. Therefore, alteration of the mortar parameters to enhance microstructure for improved mechanical strength increases the risk of DEF-related expansion. This report is also found on DVD021.
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