Suitability of soft organic clay or silt as fill material

1 Suitability of soft (organic) clay or silt as fill material 

The distinction between cohesive and organic soils is not always clear. Often clay contains some degree of organic material. For construction applications, generally a maximum organic content of 5 to 10% is allowed. 

Compared to granular material such as sand, soft soils show some typical engineering properties. These properties can have strong implications for the design of struetures eontaining these materials  

High eompressibility - potentially large vertical and horizontal displacements can cause damage to struetures and must be taken into account in the structural design (see also Section 8.5.3.5 and 8.5.3.6). 

Relatively low shear strength - often relatively large foundation structures are necessary to spread the imposed loads. There is an increased risk of slope failure (see Section 8.4.3) 

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