PHYSICAL PROPERTIES OF CONFINED DREDGED MATERIALS

Abstract

Physical properties of fine-grained dredged materials from 4 diverse locations [Philadelphia, Pennsylvania; Toledo, Ohio; Norfolk, Virgina; Mobile, Alabama; USA] were determined. The results should be useful to those involved in designing, managing and reclaiming dredged-material-confinement areas. Many of the characteristics of the material underwent irreversible changes once the materials were dried. Initially, the material behaved like a slurry, but even after one drying, the properties changed so that the materials did not reswell to their original volume, the bulk density at a given moisture content was less and the plasticity index was less. Shrinkage is linear until the moisture content decreases to about 25%. Volume decreases below this moisture content were very small. Relationships are given that allow the use of field-moisture data to determine the amount of shrinkage that has occurred, as well as that which might yet be expected. The saturated and unsaturated permeabilities of all materials are very low, indicating that subsurface drainage will remove only small quantities of water. Physical properties of the materials are most closely correlated with mineralogy and the plasticity index. Those materials with smectitic minerals and greater plasticity indices retained greater amounts of water and had lower permeabilities than materials with other clays or lower plasticity indexes.