Synergistic Regulation Mechanism of Anti-Dispersion and Flowability of Alkali-Activated Slag Underwater Non-Dispersible Slurry

The trade-off between flowability and anti-dispersion properties of alkali-activated slag slurry in underwater environments represents a key technical bottleneck limiting their application in marine underwater engineering. In this study, granulated blast furnace slag (GGBS) was used as the raw material, with the modulus of liquid sodium silicate adjusted by NaOH serving as the alkali activator, and hydroxypropyl methylcellulose (HPMC) and polyacrylamide (PAM) selected as anti-dispersion agents. This study systematically investigates the synergistic regulation mechanisms of the anti-dispersion agents’ type, dosage, and activator on the anti-dispersion properties and rheological behavior of alkali-activated slag slurry, and revealed the evolution mechanisms of the microstructure of the hardened slurry through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) analysis. The results indicate that the activator is the key factor in regulating the various properties of the slurry, and the combination of PAM and HPMC produces a significant synergistic effect. At the optimal formulation (modulus of 1.0, total blended anti-dispersion agent content of 1%, and a mass ratio of PAM to HPMC of 1:1), the slurry exhibited a wet loss rate of 38.45%, a solid retention rate of 89.98%, a flow value of 195 mm, and a 28-day compressive strength of 41.62 MPa, achieving an optimal balance between anti-dispersion performance and workability.