For the super high PI clay soils several owner representatives and engineers are specifying the combination of lime and cement using lime to reduce the PI in one step then using cement to create a strong and cohesive layer of stabilized soil. Lime alone may not have the strength, cohesiveness, and ability to set rapidly needed for a project. One should also consider this combination of stabilization for the economy if the percentage of the lime stabilizer needed exceeds 6%. Based on a University of Texas at Arlington research study by Dr. Annand Puppala, the city of Arlington adopted a 4% lime in one step and 4% cement in a two-step process. Due to the high variability of soil types, on Interstate 35 north of Hillsboro, the Waco District of the Texas Department of Transportation utilized this two-step process to ensure consistent and durable soil stabilization. There are numerous other examples. This two-step process is the method that ensures a more rapid setting, and stronger and more cohesive soil stabilization that will allow a contractor to continue paving operations immediately after this work
Because of the strength, durability, and rapid set properties of hydration, Cement is the choice when it comes when comes to the stabilization of sandy soils. However with the modern equipment in use now successful stabilization using cement alone in clay soils with the mid-range of PI is taking place all over the country. For consistency dependability, and immediate strength, and cohesiveness of stabilized soil layer many others are adopting the two-step process. The result will be stronger and longer-lasting pavements.