Environmentally benign production of one-part alkali-activated slag with calcined oyster shell as an activator

This study focuses on an environmental friendly, non-corrosive and non-viscous activator during the production of one-part alkali-activated slag using calcined oyster shell (COS) powder. Test results demonstrate improved mechanical and microstructural characteristics for specimens prepared with COS powder as an activator. The highest increment in the strengths was revealed with a 5% COS addition due to the resulting enhanced pore refinement, whereas an excessive dose resulted in a delayed rate of C-S-H formation and a significant amount of large capillary pores, thus decreasing the strength. The mineralogical and microstructural properties of the paste were also analyzed, and these findings revealed that COS powder is suitable for use as an activator to produce one-part alkali-activated materials. (C) 2020 Elsevier Ltd. All rights reserved.