Getting control of Expansive Soil
Expansive soil, also called shrink-swell soil, is a very common cause of foundation problems for road construction projects. Depending upon the supply of moisture in the ground, shrink-swell soils will experience changes in volume of up to thirty percent or more. Foundation soils which are expansive will “heave” and can cause lifting of a road structure during periods of high moisture. Conversely during periods of falling soil moisture, expansive soil will “collapse” and can result in road surface settlement. Either way, damage can be extensive.
Expansive soil will also exert pressure on the vertical face of a road foundation resulting in lateral movement. Shrink-swell soils which have expanded due to high ground moisture experience a loss of soil strength or “capacity” and the resulting instability can result in various forms of foundation problems and slope failure. Expansive soil should always be a suspect when there is evidence of active foundation movement.
In order for expansive soil to cause foundation problems, there must be fluctuations in the amount of moisture contained in the foundation soils. If the moisture content of the foundation soils can be stabilized, foundation problems can often be avoided.
This is why a pre-treatment of construction road soil with an effective ionic soil stabilizer is so important. This chemical treatment is designed to alter the clay mineralogy and reduce the expansion potential.
RoadPacker ionic soil stabilization solutions cause a reaction called “cation exchange” where “ions” or positively charged atoms in solution are substituted for other species of ion which are attached to the clay mineral crystals.
This treatment of expansive soil also causes “flocculation-agglomeration” in which the positive charged ions react with negative charged particles and create other conditions which allow the small clay particles to clump together into larger particles.
Finally, this treatment results in the formation of cementing agents within the expansive soil. The net effect of ionic soil stabilization treatment is mitigation of foundation problems by reducing in the shrink-swell potential and by increasing the strength of the treated soil.
By negating the clay’s natural ability to attract water and maximizing the soil’s ability to be compacted, the result is a an ensured long-lasting, cost-effective, maintenance-reduced project.
