M. Konert et J. Vandenberghe, COMPARISON OF LASER GRAIN-SIZE ANALYSIS WITH PIPETTE AND SIEVE ANALYSIS - A SOLUTION FOR THE UNDERESTIMATION OF THE CLAY FRACTION, Sedimentology, 44(3), 1997, pp. 523-535
Classically, the grain size of soil and sediment samples is determined
by the sieve method for the coarse ii actions and by the pipette meth
od, based on the 'Stokes' sedimentation rates, for the fine fractions.
Results from the two methods are compared with results from laser dif
fraction size analysis, which is based on the forward scattering of mo
nochromatic coherent light. From a point of view of laboratory efficie
ncy, the laser sizing technique is far superior. Accuracy and reproduc
ibility are shown by measurements on certified materials. It appears t
hat laser grain size measurements of certified materials correspond ve
ry well with the certificated measurements. Tests were also done on a
set of randomly selected sediments of fluvial, aeolian and lacustrine
origin. Except for the (<2 mu m) clay fraction, there is a coarsening
of the mean diameter of one to two size classes (0.25 phi), caused by
the non-sphericity of the particles. The platy form of the clay partic
les induces considerable differences (eight size classes) between pipe
tte and laser measurements: the <2 mu m grain size, defined by the pip
ette method corresponds with a grain size of 8 mu m defined by the Las
er Particle Sizer for the studied sediments. Using a higher grain size
level for the clay fraction, when laser analysis is applied, enables
workers in the geological and environmental held to compare classical
pipette analysis with a laser sizing technique.