ABSTRACT
Controlling the quality of compacted fill using dry density and water content can be difficult for the following reasons. Firstly, some soils are highly variable, with rapid and random changes in optimum water content and maximum dry density. Secondly, some soils do not show peak dry density and optimum water content. Thirdly, some soils are highly sensitive and conventional compaction control may be inappropriate. Compaction of clays and silts has normally been controlled by specifying limits of water content and dry density. The principal objectives in compacting soil are normally to create a fill of high strength and low compressibility, and in the case of water retaining fills, of low permeability. Many residual soils are ‘‘structured’’, and when remoulded by the compaction process the soil becomes softer. The use of the standard method involving water content and dry density as control parameters is simply impractical for many residual soils.
