Strength Behavior and Micromechanism of Waste Shredded Tire and Cement-Stabilized Dredged Clay

This study presents an experimental investigation into the strength characteristics of dredged clay treated with 10% cement, varying waste shredded tire (WST) contents, and WST particle diameters. The authors performed a series of direct shear (DS) tests, unconfined compressive strength (UCS) tests, and scanning electron microscope (SEM) analyses to investigate the effects of WST content, WST particle diameter, and curing time on the strength behavior of treated dredged clay. The DS test results showed that the values of shear strength, cohesion, and internal friction angle of the WST-cement-treated samples are significantly higher compared with the lower values of the untreated sample. For the treated samples with 10% cement content cured for 3 h, when the WST content was increased from 0% to 35%, the peak shear strength increased from 41.1 to 133.3 kPa at applied normal stress of 100 kPa, cohesion improved from 33.7 to 73.4 kPa, and the internal friction angle rose from 29.1° to 31.3°. However, higher WST contents (15%, 35%, and 50%) negatively impacted strength parameters over extended curing times (7 and 28 days), and the optimal WST content for enhancing shear strength was determined to be 35%, with particle diameters ranging from 0.5 to 2 mm, which resulted in the most favorable performance. Additionally, curing time significantly influenced the strength, with the most substantial gains observed within the first 7 days. The UCS test results showed that all treated samples exhibited strain-softening behavior. The variation laws of unconfined compressive strength with WST content, particle diameter, and curing time are consistent with those for shear strength obtained from DS tests.