Strength characteristics of metakaolin and cement stabilized dredged clay at high water content

This study presents an experimental investigation into the strength behaviors of dredged clays with high water content, stabilized using metakaolin (MK) and Portland cement (PC). Direct shear tests were conducted on dredged clay samples treated with MK and PC, maintaining a constant PC content while varying MK content and curing times. The test results revealed a similar variation pattern in the shear stress and shear displacement curves of the stabilized clay samples. Initially, the shear stress increased linearly with shear displacement until it peaked, after which it rapidly decreased, indicating a brittle failure mode. Moreover, the cohesion values (ranging from 66.0 kPa to 1189.4 kPa) showed a linear increase with MK content ranging from 0% to 12% and 15% PC content, while the internal friction angle values (ranging from 31.8° to 49.7°) exhibited a parabolic increase with curing times ranging from 2 h to 28 days. Scanning electron microscope (SEM) images illustrated the formation of numerous amorphous hydration products during curing after the addition of MK and PC. These products filled the pores and improved the interlocking of soil particles, leading to a significantly enhanced microstructure and increased shear strength of the MK and PC stabilized soil.