Page 101 - RoadCem Manual - PCT BV
P. 101

density against moisture content is made and the moisture content at which a maximum density is achieved is the optimum moisture content for a given soil (Figure 4.51).
During execution of the works in the field, the actual moisture content of the in situ soil is measured and if lower than the optimum moisture content determined during the Proctor test water is added to achieve optimum moisture content prior to compaction. If the field moisture content is higher than the opimum moisture content is than either one has to wait for the soil to dry to optimum moisture content naturally or addition of drying agents and mixing of the soil is needed prior to compaction (Cement or lime can be used as dryng agents). The first option is usually applied.
4.2.11 Settling behaviour
Weak soils have a tendency to settle under the weight of the road construction on top. If such cases, and especially when settlement is irregular unevenes of the road surface (longitudional and traversal) can occur. Settling typically occurs when the latent bound water between the grains of soils is squezed out creating room for the closer packing odf the soil grains and a resulting reduction of specific volume and thus settling. With sandy soils this typically is not a problem and almost no setting shall occur. However, with clay, silt, sludge and peat settling can continue for a few years. To control the settling measures need to be put in place. A number of options is available, the most common one being the installation of an appropriate drainage system to remove the latent (excess) water and induce the settling prior to the actual construction of the road or preloading of the foundation to the extent needed to induce the settling (less frequent). The problem of settling requiers special attention and for soils prone to settling it is advised that proper geotechnical study and advise be sought.
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