Reinforcement effect of polycarboxylate-grafted 3D porous graphene on the toughness and dimensional stability of waterglass-activated slag

The toughness and dimensional stability of waterglass-activated slag (WAS) remain crucial issues that hinder its widespread adoption. This study reveals the specific reinforcement of WAS by polycarboxylate-grafted 3D porous graphene (3DPG) through multi-scale experimental investigations. At the macro level, it is found that the addition of trace amounts of 3DPG (0.05 wt%) significantly increases WAS's 28-day flexural-to-compressive strength ratio (F/C) by 38.3% and reduces dry shrinkage (DS) by 50.5%. Microscopically, after adding 3DPG into WAS, the elastic moduli of C-S-H and C-A-S-H phases are increased by 25.0% and 17.5%, respectively, while the proportion of more-harmful pores is simultaneously decreased by 41.7% and the proportion of harmless pores is increased by 86.5%. Besides, chemical analysis further verifies that these enhancements are critically ascribed to the formation of specific (T=Si or Al) T-O-C bonds in WAS, which is induced by the abundant hydroxyl groups in 3DPG as anchoring sites interacting with [SiO 4 ] and [AlO 4 ] tetrahedra, facilitating the polymerization and cross-linking of aluminosilicate chains in C-(A)-S-H gels, thereby reinforcing the microstructure of the WAS matrix. This work provides a new route of reinforcing WAS with graphene.