Stabilization Effect of Anionic Polyacrylamide on Marine Clay Treated with Lime

Abstract

Marine clays often need improvements before construction and how to stabilize such kind of soft soil has been a great challenge. To address this issue, a newly proposed additive, which is named anionic polyacrylamide (APAM), with lime was applied to the clay stabilization. The main objective of this study is to figure out the effect of APAM on lime-treated marine clay and the micromechanism of stabilization. The unconfined compressive strength (UCS) tests and oedometer tests were performed to investigate the mechanical properties of stabilized clays; the X-ray diffraction (XRD) tests were conducted for mineralogical analysis; the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were carried out for microstructural study. The experiment results show that with APAM dosage increasing, the stabilization effect first enhanced and subsequently weakened. The mineralogical analysis reveals that no new compounds were detected as APAM was added. The microstructural study shows that the physical adsorption of APAM to clay particles was conducive to form a more stable clay structure. The Ca2+ produced by lime served as the cationic bridge, facilitating the APAM adsorption. However, the electrostatic repulsion between APAM and negatively charged clay particles and the inhibitory effects of APAM on pozzolanic reactions were the main factors weakening the stabilization effect. This study indicates that the APAM/lime treatment method is efficient for marine clay stabilization as long as a rational APAM dosage is selected.