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Dredged clay with high water is difficult to use directly in practical engineering due to its extra-low strength. So, a solidifying treatment is often used to improve its engineering properties. In this study, a number of unconfined compression shear tests were conducted to investigate the strength behavior of cemented dredged clay with straw at different curing stages. For cemented dredged clay cured for a few days, the addition of filamentous straw and powdered straw would enhance its unconfined compressive strength (qu). Then, a decrease in qu is observed for samples with a small straw content as the curing time increases, mainly due to the deterioration of the straw. However, solidified soil amended by granular straw sees its qu decreases with increasing straw content decreasing its compactness and integrity. In addition, the failure strain (εf) varies mostly within the range of (1.0% and 4.0%) and basically decreases with the increasing curing time and straw content. For the cemented dredged clay used in this research, the straw less than 6 mm with a ratio of sample diameter-to-straw length greater than 6.7 is helpful for improving the early-stage strength behavior when the straw content is less than 8%. [ABSTRACT FROM AUTHOR]

The dredged clay (DC) could not be directly reutilized for its extra-high water content. So, the dewatering is needed before further improvement. At present, the commonly used self-weight sedimentation and natural air-drying are often difficult to meet the engineering requirements and time-consuming, thus chemical flocculants are used to improve the dewatering process for their excellent flocculation in recent years. In this study, the flocculant effects on the fluidity and strength behavior of cement-treated dredged clay, are investigated based on experimental results. For the dredged clay, its fluidity firstly increases with the increasing content of FeCl3 and Chitosan, and then reaches a stable value; while the addition of PAM would decrease its fluidity. Compared with the dredged clay, relatively small changes in the fluidity of solidified dredged clay are found with the addition of flocculants. The flocculant with a suitable dosage has an overall enhancement in the undrained strength of solidified soils. The flocculation of dredged clay/cemented clay induced by the flocculant is responsible for changes in the fluidity and undrained strength. For flocculants used in this study, the appropriate content corresponding to the target fluidity and maximum strength is in the range of 0.1% to 0.5%. [ABSTRACT FROM AUTHOR]