A case study for Improving the performance of CaO-activated slag by the reaction behavior of CaO and NaHCO3

In Alkali-Activated Slag, a contradiction exists among pH, setting speed, and strength development. In this study, the reaction behavior between CaO and NaHCO3 is harnessed to regulate the setting speed while optimizing the material properties. The results demonstrated that the pore solution pH of Alkali-Activated Slag rose to over 12.4. At C5S100, the workability and setting time of the material were comparable to or even surpassed those of ordinary Portland cement. It exhibited a compressive strength of 53.9 MPa at 28 days, which was an 85.2 % increase compared to C5S0, and over 70Mpa at 90 days. Additionally, in the microscopic characterization tests, the composite activator facilitates the dissolution hydration of slag, generating more hydration products. This leads to a more compact structure and lower porosity, thereby enhancing the overall performance. This composite activator strategy effectively reconciled the conflict between the practicality of Alkali-Activated Slag and the setting speed and strength development.