Structural Soils
Structural soils are specialized base-course mixtures of open-grade aggregate and soil formulated to
support various types of pavement while maintaining favorable growing conditions for vegetation (see
Figure 5.8). Void spaces in the mixture are partially filled with soil, with the remaining open space
available as a temporary water reservoir. The open-grade aggregate supports traffic load and protects
the underlying soil from compaction, which helps maintain healthy root growth (Ferguson 2005).
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