TITLE:
Sieving Error from Dry-Separating Silt-Sand-Gravel Soils
AUTHORS:
Hans Rönnqvist
KEYWORDS:
Laboratory Tests, Particle-Scale Behavior, Silts, Sands, Gravels, Standards & Codes of Practice
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.9 No.4,
November
25,
2019
ABSTRACT: The dry-separation method is an alternative to the wet-preparation in the
current European Standard for the determination of particle size distributions
by the sieving of soils. Due to the risk of error, dry-separation is cautioned
against in the standard; however, there is no additional guidance as to when it
is unsuitable nor for the magnitude of error that it may introduce. This study
investigates the dry-separation method as an alternative by comparing with the conventional method of Wet-preparation in terms of particle-size distributions of eight cohesionless sand-gravel
soils with varying amounts of nonplastic fines. The findings indicate a
gradually increasing sieving error for fractions at minus 0.5 mm with the amount of fines in the
soil, and depending on the fines content of the soil, dry-separation introduced
errors upwards of 45% in silt-sand-gravel soils. An
empirical best-fit formula is proposed for the
estimation of the error using the dry-preparation method on this type of soil.
Furthermore, to avoid sieving errors, the results suggest that the dry-separation method should not be used for silt-sand-gravel
soils exceeding 2% silt size fractions.