Reusing Dredged Material through Stabilization with So-Called Bio-Enzyme Products

Sediments are dredged from waterways to maintain maritime activities and prevent floods. Exorbitant amounts of money are budgeted for the removal of dredged material (DM) and its disposal in landfills. We investigated the potential for reuse of DM as a road construction material using so-called bio-enzyme products as stabilizing agents. To improve the mechanical properties of DM, such as compressive strength, compressibility, Atterberg limits and the California bearing ratio (CBR), mixtures of DM were tested with two different amounts of a commercially available bio-enzyme product, which yielded enzymatically stabilized dredged material (ESDM). Unconfined compressive strength (UCS), compaction and Atterberg limits were measured in accordance with ASTM specifications on all samples. Data show that the addition of bio-enzymes resulted in increases in UCS but did not affect the optimum moisture content (OMC), maximum dry unit weight or Atterberg limits of the DM. A comparative field study was carried out to evaluate the CBR of the CH subgrade before and after treatments with the bio-enzyme product and with lime as a traditional stabilizing agent. The results of the field study supported the laboratory findings. Based on these data and results from the literature, models predicting the effect of bio-enzyme treatments on the value of CBR and of UCS were developed statistically. These models also underlined the importance of the clay fraction and PI values for the improvement of the engineering properties of soil using bio-enzyme additives.

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