Effect of mixing method on the performance of alkali-activated fly ash/slag pastes along with polycarboxylate admixture

The addition sequence of raw materials during mixing is one factor that affects the fresh and hardened properties of ordinary Portland cement (OPC). Similar to OPC, the properties of alkali-activated materials (AAMs) may be susceptible to the mixing procedure, yet the mixing procedure's effect is still unclear. This research aims to investigate how different mixing procedures affect the fresh and hardened properties of the Na2SiO3-anhydrous alkali-activated materials along with polycarboxylate superplasticizer. Besides, a new mixing method named "hybrid-mixing" is proposed, evaluated, and compared with the conventional one-part (1 GP) and two-part (2 GP) mixing methods. It was found that the mixing procedure markedly affects the fresh and hardened properties of AAMs without changing their chemical composition. Compared with 1 GP and 2 GP binders, the hybrid-mixed binders achieved a relatively better slump-flow and compressive strength. The mechanisms governing different mixing methods are further discussed.