EFFECT OF POLYACRYLAMIDE ON CEMENT PASTE

Abstract

This study measured the carbonation depth and pH value to examine the impact of polyacrylamide on the carbonation behaviours of cement pastes. Thermogravimetric analysis, scanning electron microscopy, mercury intrusion porosimetry, X-ray diffraction, electrochemical impedance spectroscopy, and thermo gravimetric analysis were used to track hydrate and microstructure changes in cement pastes and analyze underlying causes. The findings demonstrate that polyacrylamide increases the amount of CH that is available for carbonation by reducing the amount of portlandite (CH) and changing its morphology from a bigger size with a parallel-stacked lamellar structure to a smaller size with an edge-corroded structure. In the presence of polyacrylamide, larger Ca/Si ratios of C-S-H phases with a greater carbonation rate form. In the presence of polyacrylamide, larger Ca/Si ratios of C-S-H phases with a greater carbonation rate form. Polyacrylamide fills in capillary pores with gel pores during carbonation, reducing porosity and improving pore refinement. This is accomplished by using small-crystal CaCO₃ grains. Overall, in a dosage-dependent way, polyacrylamide accelerates the carbonation of cement paste.