Cohesive or fine-grained fill materials

In some cases, the use of cohesive or fine-grained soils like silt and clay can be an economical alternative for the use of sand as fill material, for instance, when only cohesive soils are (economically) available in the vicinity of the reclamation area or when large volumes of cohesive soils become available from excavation or dredging at the project area itself. As an alternative to granular material like sand, some of these cohesive soils can be (made) suitable for use as hydraulic fill. 

The advantages of using these soft soils as fill material are  

Although the use of cohesive soils as fill material is possible, specific constraints concerning the design and construction of hydraulic fills must be taken into aeeount. Some problems associated with the use of cohesive soils are  

Other compaction techniques are required compared to sandy soils. Compaction methods based on vibration are not applicable in the case of cohesive or fine-grained soils, see Chapter 7. Table 9.1 gives an overview of some frequently encountered cohesive fill materials. 

Dredged soil Soil characteristics in the borrow area Resulting cohesive material within the reclamation area Ref.  

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In some cases, poor quality fill material will have to be used. Reference is also made to section 9.1 Cohesive or fine-grained fill materials for a more detailed description on the use of poor quality fill material. A shortage of sand sources in the close vicinity of a project or environmental constraints may have as a consequence that one is forced to work with cohesive materials for the land reclamation. In these cases the shear strength of the fill, and its increase in time, is much more difficult to predict compared to the use of high quality fill materials. A good knowledge of dredging and deposition methods is necessary. 

Cohesive or fine grained fill material (see Section 9.1)... 

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