An experimental study on dredged Qinhuai river sediment-based flowable fill treated by flocculation-cementation method

Abstract

The traditional Portland cement solidification method has low efficiency in treating dredged sediments with high water content. In this study, flowable fill was prepared using dredged sediments by the flocculation-cementation method. By utilizing dredged sediments with high water content, the need for additional water during the flowable fill preparation process is eliminated. The influences of flocculant types and dosages on dehydration efficiency, flowability, and strength were investigated through a series of laboratory tests, including settling column tests, rapid dehydration tests, flowability tests, and unconfined compressive strength (UCS) tests. The results indicate that the use of flocculants improves the dehydration efficiency. The dehydration efficiency of guar gum is the highest, with a settlement rate reaching 78 mL/min during the settling stage. The inclusion of flocculants clearly impacts the flowability and UCS of flowable fill, and the addition of amphoteric polyacrylamide and guar gum decreases the flowability. Furthermore, the Portland cement dosage also has a significant influence on both the flowability and the UCS. As the cement dosage increases, the flowability decreases while the UCS increases. To study the effectiveness of flocculation-cementation method in treating dredged sediment, four sets of recommended schemes are provided based on the actual transportation and re-excavation methods employed in the project to cater for different requirements. This research holds significant reference value for both the resource utilization of dredged sediments with high water content and the engineering application of flowable fill.