The US Army Corps of Engineers (USACE) is responsible for this type of maintenance in federal navigation channels. Because water is always moving and naturally carrying materials that settle and need to be dredged, maintenance dredging is a constant, cyclical process of upkeep. Maintenance dredging is predominantly used as a means of maintaining required depths for boats and ships to safely traverse navigation channels. This technique improved the hydraulic conductivity of fine-dredged material and could contribute to the efforts of increasing reuse of waste by-products for engineered fill applications.What is the purpose of maintenance dredging? This new product, engineered geopolymer soil (EGS), was classified as poorly graded sand (SP) with a hydraulic conductivity at least two orders of magnitude higher than that of the original FDM. The AAFA cement caused FDM soil particles to flocculate, which led to an increase in particle diameters. To increase the hydraulic conductivity, Class C fly ash, an industrial by-product from the local power plant in Duluth, MN, was activated with a combination of alkaline activator solutions, sodium hydroxide (NaOH) and sodium silicate (Na2SiO3), to generate alkali-activated fly ash cement (AAFA). A sample of fine dredged material (FDM) from the Erie Pier facility in Duluth, MN, was classified as sand lean clay (CL) with a hydraulic conductivity of 6.06 x 10-6 cm/s. This work investigates an engineered solution to the waste materials piling up in a disposal facility in northern Minnesota. Much research has been done on methods of improving hydraulic conductivity through soil improvement techniques available today. Hydraulic conductivity is a vital input parameter when designing foundations, embankments, retaining walls, or roadways.
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