Comparative study on the properties of cement grout modified with PAM and PANA at elevated temperatures

A comparative investigation of cement grout doped with anionic polyacrylamide (PAM) and sodium polyacrylate (PANA) at elevated temperatures was conducted. The results revealed that both the PAM and PANA significantly decreased the bleeding rate and improved the apparent viscosity. After adding 1% content of PAM or PANA, the bleeding rate decreased from 16.484% to 5.311% and 7.146% at 20 °C, while 17.528% to 11.911% and 9.739% at 80 °C. The cement grout doped with PAM exhibited higher viscosity and stronger washout resistance. PAM and PANA reduced compressive strength at high temperatures but eliminated the difference between the upper and lower parts, as it decreased from 131.77% to 29.94% and 48.74% respectively. The quantity and morphology of C-S-H gels were changed, related to the hydrogen bonds, the crosslink of admixtures, and the formation of micro-gels. The differences between the PAM and PANA are in conjunction with the molecular structures and the resulting behaviors.