Influence of flocculant type, dosage, and water content on sedimentation behavior of dredged clay
Yupeng Cao,Yan Xu,Xiang Yong,Nuo Xu,Jie Yin,Naibin Sun
Abstract
Dredging activities associated with waterway and infrastructure construction generate large volumes of high-water-content dredged clay, whose poor sedimentation and dewatering characteristics pose significant challenges for earth structures and ground engineering applications. An improved understanding of the sedimentation behavior of such geomaterials under flocculant treatment is therefore essential for effective reuse and engineering design. In this study, a systematic experimental investigation was conducted to examine the effects of flocculant type, dosage, and initial water content on the sedimentation behavior of dredged clay. Sedimentation column tests were performed on clay suspensions treated with four representative flocculants, including superabsorbent polymer (SAP), polyacrylamide (PAM), polyaluminum chloride (PAC), and calcium hydroxide [Ca(OH)2], over a wide range of dosages and initial water contents. Settlement evolution, sedimentation rate, and post-sedimentation water content distribution were quantitatively analyzed. The results indicate that flocculant treatment markedly accelerates sedimentation and increases final settlement compared with untreated clay. For all flocculants, both settlement and peak sedimentation rate exhibit a non-monotonic dependence on dosage, with an initial increase followed by a reduction at higher dosages, indicating the existence of an optimal dosage range. Among the flocculants investigated, SAP demonstrates the most pronounced enhancement of sedimentation performance, particularly at higher initial water contents, owing to its strong water-absorption capacity and effective particle aggregation. The optimal SAP dosage increases with increasing initial water content, highlighting the coupled influence of slurry state and flocculant content. In addition, post-sedimentation water content shows clear vertical stratification within the slurry cake, reflecting differences in particle size distribution and drainage conditions during settling. The experimental findings provide quantitative insight into the sedimentation mechanisms of flocculant-treated dredged clay and offer practical guidance for the selection and optimization of flocculants in earthwork, ground improvement, and dredged material reuse applications.
Yupeng Cao — College of Civil and Transportation Engineering, Weifang University, Weifang, 261061, China; Shandong Key Laboratory of Intelligent Manufacturing Technology for Advanced Power Equipment, Weifang, 261061, China
Yan Xu — School of Modern Agriculture and Life Sciences, Weifang University, Weifang, 261061, China
Xiang Yong — School of Civil Engineering, Shenyang Jianzhu University, Shenyang, 110168, China
Nuo Xu, Jie Yin — Department of Civil Engineering, Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang, 212013, China
Naibin Sun — Shandong Provincial Road and Bridge Group Co., Ltd., Jinan, 251400, Chin
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