The accelerating mechanism of alkali free liquid accelerator based on fluoroaluminate for shotcrete

In this paper, the alkali free liquid accelerator based on fluoroaluminate (AAF) was prepared, and its effect on the setting time of cement paste and compressive strength of mortar was studied. The influences of the AAF on hydration process of cement paste, the composition and morphology of the C3A and C3S early hydration products were investigated by isothermal calorimetry, XRD and SEM analysis. The results show that the increase of the AAF dosage could greatly shorten the setting time of cement paste, but it also caused the 1d compressive strength of mortar to decrease. In addition, the early hydration conceptual models of the C3A and C3S in presence of AAF were established based on the experimental results.