Earthwork Specifications for Land Development & Water Retention (for Dams, Landfill & Wetlands)
SITE Geotechnical can provide guidance on the specification, execution, and control testing of earthworks and associated site preparation works for investigations, recommendations, construction considerations, material assessment for many types of works requiring earthworks associated with pavements, water retention structures, land fill sites and land development.
Density Ratio, Relative Compaction
The degree of compaction specified and achieved in cohesive soils is usually expressed as a density ratio, as described in AS 12188.8.131.52. This compares the density of the compacted soil with a reference density, being the peak density which can be achieved in a controlled laboratory compaction process, e.g. Standard Compaction, AS 12184.108.40.206. Density Ratio is also sometimes referred to as Relative Compaction. This more generic term allows for other reference testing procedures such as Hilf Rapid Compaction (AS 12220.127.116.11) for clay fills.
Field Density Testing
To allow comparison of the achieved field compaction with a laboratory reference density, it is necessary to be able to reliably determine the achieved field density and moisture content. The commonly used methods for assessing field bulk density is the nuclear density gauge (AS 1218.104.22.168), but moisture content usually is measured in the laboratory. Indirect measures of achieved compaction include penetrometer testing. The Perth Sand Penetrometer (PSP) is often used in clean sands, with the number of blows required to drive a blunt ended rod into the sand taken as an indicator of the relative compaction of the sands (see PSP). The Dynamic Cone Penetrometer (DCP) provides a similar correlation for all soil types.