Influence of wet-ground GGBS on the workability of cement slurry

Wet grinding is an effective technical means to enhance the utilization of ground granulated blast furnace slag (GGBS) in cement-based materials. This study focuses on the influence of wet-ground GGBS (W-GGBS) on the working performance of cement slurry. The research results indicated that W-GGBS deteriorated the workability of cement slurry, and the longer the grinding time, the greater the negative impact. When the grinding time was 40 min, the introduction of W-GGBS reduced the fluidity of the fresh cement slurry without PCE from 205 mm to 190 mm. For the cement slurry plasticized by PCE, the fluidity decreased from 235 mm to 170 mm. However, the underlying mechanism was different. The large specific surface area of W-GGBS, which reduced the water film thickness (WFT), was responsible for the low fluidity of cement slurry without PCE. For the cement slurry plasticized by PCE, workability was jointly influenced by WFT, PCE adsorption behavior, and the molecular conformation of unadsorbed PCE. W-GGBS demonstrated a superior affinity for PCE compared to GGBS, improving the adsorption amount of PCE, which was beneficial to workability. However, W-GGBS released large amounts of cations during the wet grinding process, leading to cross-linking of unadsorbed PCE, which was detrimental to workability. Coupled with the negative impact of W-GGBS on WFT, the fluidity of cement paste is macroscopically manifested as a decrease. These findings elucidated the different mechanisms by which W-GGBS affected the workability of cement pastes with and without PCE, providing a theoretical foundation for subsequent research on workability regulation measures.