Compressibility and microstructural mechanism of PC-SSstabilized dredged clay at high water content

This study systematically investigates the compressibility of dredged clay with high water content using Portland cement (PC) and sodium silicate (SS) as composite stabilizers. The effects of SS content (0%, 3%, 6%, 12%) and curing time (3 hours, 7 days, 28 days) on compression behavior of PC-SS-stabilized specimens with the same PC content of 10% were investigated via one-dimensional consolidation tests, with microstructural evolution analyzed using SEM. Results show that PC-SS-stabilized soil exhibits significantly reduced compressibility compared to untreated soil. The e-lgp curve became bilinear, with a yield stress (py) as the turning point, compressibility was low before py and increased markedly after. Compression indices (Ce, Cc) of stabilized soil were lower than those of untreated soil, initially decreasing and then increasing with SS content, reaching minima at 6%. The swelling index (Cs) was also the smallest at this content. Yield stress increased rapidly, then slightly decreased with SS addition, peaking at 6%. Longer curing time increased yield stress, most notably within 7 days, reduced porosity, and decreased compressibility. After 28 days, compression curves shifted upward. Microstructural analysis indicated that at 6% SS and 10% cement, continuous cementitious products formed, filling pores and cementing particles, thereby enhancing compressive performance.