Title: Utilization of Steel Furnace Aggregate in Geopolymer Concrete for Wave-Breaker Application
Author(s): Arnaud Castel, Mohammad Khan, Aziz Mahmood, and Stephen Foster
Publication: Symposium Paper
Appears on pages(s): 25.1-25.10
Keywords: Geopolymer; manufactured aggregate; wave-breaker structures; free lime; climate adaptation
This paper evaluates the performance of steel furnace slag (SFS) aggregate in low calcium geopolymer concrete and its potential to be used in making high-density concrete for application in breakwater armour units. The geopolymer binder is a blend of 90% low calcium fly ash and 10% ground granulated blast furnace slag (GGBFS). Mechanical properties, shrinkage, and detailed microstructure analysis were carried out. The results showed that geopolymer concrete with SFS aggregate offered higher compressive strength and elastic modulus than that of GPC with traditional aggregate. The shrinkage results showed no expansion or swelling due to delayed calcium oxide (CaO) hydration after 320 days. No traditional porous interfacial transition zone (ITZ) was detected using scanning electron microscopy, indicating a better bond between SFS aggregate and geopolymer matrix. Energy dispersive spectroscopy results further revealed calcium (Ca) diffusion at the vicinity of ITZ. Raman spectroscopy results showed no new crystalline phase formed due to Ca diffusion. The incorporation of Ca into the geopolymer structure and better bond between SFS aggregate and geopolymer matrix are the most likely reason for the higher compressive strength observed in GPC with SFS aggregate. The Incorporation of the relevant concrete properties in Hudson’s equation shows that SFS aggregate geopolymer concrete can significantly improve the stability of breakwater structures.