Geotechnical Properties of Cement Treated Dredged Sediment to be Used as Transportation Fill

In order to investigate the potential uses of treated dredged sediment as fill material in transportation related projects, a comprehensive series of laboratory tests was conducted on dredged sediments from the Hudson River. The dredged sediments were mixed with Type I Portland Cement (9%, 11%, and 13% by wet weight) at three different water contents (90%, 130%, and 170%). The tests conducted on these cement treated sediments were index properties, compaction characteristics, unconfined compressive strength, consolidation tests, consolidated-undrained triaxial tests and x-ray diffraction analyses. Following cement treatment, tests have indicated that the material becomes inorganic low plasticity silt (MH) whereas the untreated sediment is classified as organic clay/silt of medium to high plasticity (OH). Compaction characteristics tests indicate that the samples have a relatively flat-shaped curve, with an optimum water content of approximately 40%, which is significantly lower than the field values. The unconfined compression tests suggest that 90% water content and 11% cement content are optimal for strength development (482.6 kPa (70.0 psi) at 28 days and 246.8 kPa (35.8 psi) at 7 days). The data suggests that remolding has a significant adverse effect on strength development. The consolidation tests show that the reduction in void ratio decreased with increasing cement content and decreasing water content and the compressibility of the samples changed in the same way. Hydraulic conductivity increased with increased levels of cement treatment. Based on consolidated-undrained triaxial testing the effective friction angle for the treated sediments ranged from 43° to 44.9° and the cohesion intercepts ranged from 0.1 to 0.5 MPa (0.8 to 5.3 psi). Overall based on the present study, it can be concluded that the cement treated dredged material can be used in a cost-effective way as non-structural or embankment fill. The findings of this study are being compared to recent studies of similar type to evaluate the results.