Determination of the water retention
curve and soil shrinkage
The water retention curve (WRC) was
determined at 8 different water suctions.
The saturated samples were drained at-10,
-20 and -30 hPa on sand tanks. The drainage
of the samples at water tensions of -60, -
150, -300, -500 hPa occurred on ceramic
plates and of -15000 hPa in a pressure
chamber. When the samples attained
equilibrium with the applied vacuum, the
gravimetric water content was determined.
At the end, samples were dried in an oven
at 105 °C for 16 hours (Hartge and Horn,
1989) to determine and to control the bulk
density and volumetric water content. To
determine the total porosity, a particle
density of 2.63 Mg m-3 was used resulting
from the dominant quartz.The shrinkage of the repacked samples was
measured during the determination of the
WRC. To estimate the vertical shrinkage
of the soil their actual height was measured
with a calliper at 6 defined points (1 on the
middle and 5 on the sides) as was proposed
by Peng and Horn (2005).