The effect of various polysaccharide-based admixtures on the properties of cement grout at elevated temperatures

The viscosity of the cement grout, affecting the water bleeding and particle sedimentation, is the key parameter in the control of water inrush disasters, and it is significantly affected by the temperatures. In this paper, various polysaccharide-based admixtures were used to thicken the grout at elevated temperatures. The water bleeding and viscosity of the cement grout doped with xanthan gum (XG), guar gum (GG), locust bean gum (LG), and konjac gum (KG) were conducted at 20 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C. The differences in density and compressive strength between the upper and lower parts of the hardened grout were calculated to evaluate particle sedimentation, and microscopic analyses were conducted. The results indicated that the gums reduce water bleeding and enhance viscosity. However, the improvement in water bleeding reduction weakened as temperatures rose, while viscosity continued to increase. The addition of gums led to a decrease in the density and compressive strength of the hardened grout, but it also reduced the differences between the upper and lower parts were. Among the various gums tested, GG demonstrated a more pronounced effect in reducing water bleeding, enhancing viscosity, and decreasing particle sedimentation when compared to others. Additionally, the incorporation of various gums did not alter the mineralogical phase compositions. SEM results revealed the presence of films covering the surface of particles, which resulted from crosslinking and complexation between active functional groups within the polymer chains and Ca2+ and Al3+ ions. Moreover, elevated temperatures were found to increase the Al/Ca ratio within the C-S-H gels, leading to the formation of C-A-S-H gels characterized by higher Al/Ca and Si/Ca ratios.