Compaction information from Electronic Blueprint for architects
Soil compaction is;
- the application of energy to loose soil,
- to consolidate it, and to remove air voids,
- thus increasing its ability to support vertically applied loads without settlement.
Loose soils consolidate and settle when subjected to vertical pressure from buildings,
retaining walls or vehicles. When a heavy load is applied to a soil, there may be some
elastic deflection (i.e. the soil partly springs back to its original position after a
load is removed). However, most of the settlement is irreversible and results from the
expulsion of the air and water from within the soil.
The purpose of mechanical compaction by rollers, plate vibrators and the like is to
reduce the air voids during construction, increasing the in-situ density. This has the
following beneficial effect.
- Increasing the bearing capacity;
- Reducing the incidence of further in-service consolidation and settlement;
- Reducing the shrink / swell effect in reactive soils.
Architects should ensure that designs and specifications make proper provision for adequate
compaction, and that tender prices allow for the level of compaction specified in these
documents.
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