Hardscape & GradingQuestion 61 of 100

Compaction of subgrade soil before hardscape is measured against what standard reference?

a.The color of the soil
b.The soil's pH
c.The number of passes only
d.A percentage of maximum dry density (for example, 90 to 95 percent)

Explanation

Compaction is specified as a percentage of a soil's maximum dry density determined by a laboratory Proctor test, commonly 90 to 95 percent for hardscape subgrade. Field testing verifies the soil reaches the required density. Adequate compaction prevents future settlement under pavement.

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