The soaking in water (due to subsurface water table fluctuation or environmental
effect) increases the strength loss of a cement stabilized soil by time and decreases the
in situ bearing capacity in some construction works. Few other adverse effects include:
(1) increase in settlement of building foundation, (2) increase in loosening of
the surrounding soil in excavation work, (3) increase of volume change and erosion
deterioration due to weathering effect, (4) increase in loss of strength in cement
stabilized soil slopes, (5) increase of erosion, (6) increase of erosion damage (land
subsidence, chemical corrosion of the soil).
Even in other techniques of stabilization and reinforcement of soil such as the
mixing ground modification and grouting, the soaking in water of a cement stabilized
soil influences the compressive strength and compressibility of soil cement
columns (Tatsuoka et al., 1997).
The water intrusion during soaking especially in active bentonite creates swelling
and disrupts the interparticle contacts and the cement bonds. This absorbed water
fills in around the old contacts and the strength of the cement stabilized clay is
reduced.
Simultaneously the relative high water content tends to isolate the individual
particles and aggregates with result the effective stress to become lower.
If soils stabilized by cement contain montmorillonite swelling can occur as water
enters the weakly bonded interlayers of the montmorillonite, whereas the strongly
bonded substrate by cement reduces the swell potential.
The importance of swelling may briefly be envisioned if we consider an unsaturated
embankment that exists at a given density (compaction). If suddenly saturated,
such an embankment, if composed of an active clay such as montmorillonite, would
swell thereby decreasing the strength. This reduces the interparticle forces and makes
the embankment more susceptible to erosion.