I would like to make some points to try to explain ionic
soil stabilizers.
Soil stabilizer is not the correct term, but it is the one
commonly used. Compaction aid or soil
consolidation aid are the more correct descriptive words, but the soil is
modified and performance is much more stable in high clay soils – so the term
stabilizer does apply.
In order to be able to conduct some performance testing on
treated soil, one needs to understand the way in which the product reacts with
the soil. Clays contain certain cations
with an ionic imbalance, and in nature the way this ionic imbalance is
satisfied by water. These cations
attract and “hold on to” a large number of water molecules, called adsorbed
water, which surround the clay particle and these water molecules can only be
removed by high pressure or temperature e.g. in a potters kiln. The fact that you try to compact water coated
molecules reduces particle interlock and so reduces strength, this is usually
referred to as plasticity.
The ionic stabilizer exchanges these cations in the clay with
ones that are in ionic balance and the adsorbed water that was previously held
onto by the clay is now released and has to make its way up to the surface of
the treated layer to evaporate from there. This water release takes time and
depending upon the soil type, traffic and weather conditions can take up to 30
days. During this time, the treated
layer becomes more dense as well as drying out and so increases in strength.
Depending upon the product used the soil will not re-adsorb the water as it has
previously and therefore exhibit higher strength even in wet weather. In essence the effect is one of the reduction
in susceptibility to moisture of clay based roads.
The treatment is non cementitious like lime or cement or
other methods like polymers. So the soil will achieve it natural strength
rather that that provided by the above methods.
In testing the effects of this treatment, one has to prepare
two sets of samples, one treated and one untreated. Both samples have to be let to dry out for 10
to 20 days and then tested and a significant improvement in the treated samples
will be noted over the untreated samples.
By: Rhino Rohrs
www.cbrplus.com / www.gravelock.com
