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Change in treatment
Treatment no. 1
(saline water)
Treatment no. 2
(distilled water)
Control percolated with
distilled water since the
start
Time in hours
1
Fig. 13.6
Percolation trial with saline water followed by distilled water (Servant 1970).
nonsaline water. But in the sample, this percolation of saline
water had the effect of replacing Ca and Mg by Na.
2. Swelling. Sodic 2/1 type clay minerals, even non-swelling, increase
in volume when saturated with water. In the sample subjected in
the second place to the percolation trial with pure water, there
was expansion of the Na-clays and, therefore, diminution of pore
space.
3. Dispersion and osmotic disruption. At the moment when pure water
is introduced into the sample, the aggregates are richer in salts.
Osmosis takes place. The pure water penetrates these aggregates
rapidly and explodes them, destroying the residual interstitial
pore space (Amezketa and Aragüés 1995).
Other similar experiments have been reported in the literature
(Bresler et al . 1982). An example is given in Fig. 13.7.
ESP = 12%
Hydraulic
conductivity
in mm/hour
ESP = 100%
ESP = 32%
Salt concentration in the saline solution, meq/l
Fig. 13.7 Relation of conductivity to salt content (Bresler et al . 1982); with ESP = exchange-
able sodium percentage.
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