Page 128 - RoadCem Manual - PCT BV

ROADCEM
RoadCem/Cement treatment falls in the second category and makes the use of these materials for pavement structure viable and justified.
Expansive soils
These clay soils exhibit particularly large volumetric changes (swell and shrinkage) following variations in their moisture contents. They shrink and crack when dry. The cracks allow water to penetrate deep into the soil, hence causing considerable expansion which results in deformation and failure of the pavement if these materials are used.
TRADITIONAL
Typical traditional treatment methods for such soils include:
• Realignment, where possible avoiding.
• Excavation and replacement.
• Chemical treatment.
• Control of moisture changes.
ROADCEM
RoadCem/Cement treatment falls in the third category and makes the use of these materials for pavement structure viable and justified. The mechanism of action is the control of swell and shrinkage behavior of such soils.
Collapsible sands
These soils exhibit a weakly cemented soil fabric which, under certain circumstances, may be induced to rapid settlement. A characteristic of these soils is that there are all unsaturated, generally have a low dry density and a low clay content. At In-situ moisture content there can withstand relatively large imposed loads with little or no settlement. However, without any change in the loading but an increase of moisture content significant settlement can occur (figure 5.22). The rate of settlement will depend on the permeability of the soil.
Figure 5.22 Collapsable sands behavior with moisture content increase
128