Hydro-Compaction of Sand Fills
Assistant Professor, Department of Applied Geology and the Environment,
Compaction of backfill materials is normally carried out by mechanical means, to achieve a specified percentage of compactivity. In some cases, hydro-compaction is used for the same purpose.
The present study discusses the results of field and laboratory experiments carried out on sand fills, by application of water over the sand. Field experiments were conducted in two pipe laying trenches, with two layers of sand 1m and 0.6 m thickness respectively, while in laboratory experiments, a 200-liter drum was used. Field density tests and moisture contents were measured in the trenches after two periods of draining (2 and 18 hours). In the drum tests, the same sand was tested, but also after being washed from fines.
The results indicate that hydro-compaction failed to achieve the required percentage of compaction (95%) for structural fill. About 40% of the tests meet the requirement for non-structural fill, however the high heterogeneity of the results make it difficult to adopt the method for compacting even non-structural fills. Laboratory experiments gave slightly better results, yet not 95%. Washed samples gave even better results, although the fines content does not exceed 5%.
Keywords: Compaction, sand fill, hydro-compaction, moisture content, maximum density
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