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Soil Stabilization: What it is and Why it Matters

October 6, 2021

Filed Under: Soil Stabilization

When building structures such as roads, buildings, or parking lots, you want it to be sturdy from the ground up. That’s where soil stabilization comes into play. Soil stabilization allows for the physical properties of the soil currently on a job site to be transformed to provide a stronger foundation for a project. This process is essential for long-lasting structures and can help cut down on project costs. At Gray & Son, we have decades of experience with the soil stabilization process and pride ourselves on being a leading soil stabilization contractor in Maryland. Here, our experts explain what soil stabilization is and why it is important for your job site. 

The Process of Soil Stabilization 

Soil stabilization is the process through which the physical properties of soil are transformed to achieve permanent improvements in strength and structure. It is often used if the original soil available at a construction site is not suitable for its intended purpose. 

Testing the Soil

The process begins in a laboratory. Scientists examine soil samples to determine how much of a particular chemical modifier is necessary to permanently stabilize the soil. Tests such as the Eades and Grim pH test, which estimates the soil-lime proportion requirement for stabilization, are run to determine the necessary amount of chemicals to break down and modify the soil, or the application rate. Typical application rates by weight of the soil range from 4 percent to 10 percent, depending on the moisture content and soil type. 

Applying the Modifier 

From there, soil stabilization happens directly on the job site. Stabilization material is delivered to the site by a pneumatic tanker attached to a semi-truck and spread evenly throughout. The team at Gray & Son can accurately place the mixture at the prescribed application rate and minimize dust by using our off-road, six-wheel Volvo A25C truck, which has been converted to include a 25-ton capacity material storage tank. A computer-controlled material spreader on the truck places the modifier at the appropriate application rate. 

Mixing the Soil 

Once applied, the modifier is mixed with the soil. This can be accomplished through a variety of methods. At Gray & Son, we utilize a Caterpillar RM-350B rotary reclaimer, which mixes the modifier into the existing soil up to 1220 inches deep. Several passes are made to ensure complete mixing. 

Chemical Reactions

As this modifier is being mixed with the soil, several reactions are taking place. Physical modifications occur through pozzolanic reactions, resulting in a stronger physical structure of the soil. Lime in the chemical modifier works to increase the pH of a soil, reducing the amount of silica and alumina that are naturally presented in soils containing clay. As the silica and alumina react with the calcium from the lime and water present in the soil, calcium-silicate-hydrates (CSH) and calcium-aluminate-hydrates (CAH). This reaction is the same that occurs when making cement, and allows for the creation of permanent bonds that will drastically increase the amount of weight soil will be able to support. 

Some modifiers may need a brief period of rest to ensure that all reactions are completed. Once this period is up, compaction, grading and a final smooth roll ensure that the soil is ready for construction. 

Importance of Soil Stabilization 

The chemical reactions that occur during the stabilization process are extremely important for a long-lasting, strong base for your project. Soil stabilization can drastically reduce permeability, resulting in reduced shrink or swell potential and increase freeze-thaw resistance. This will help to prevent any cracking or shifting of asphalt or concrete. In addition, soil stabilization can reduce the soil’s plasticity index. The plasticity index measures the range of moisture content of soil and decreasing this allows for the soil to be more friable and workable.

While the process of soil stabilization may require an additional step at the beginning of a project, it proves to be well worth it in the long run. A stronger base will result in a sturdier, longer-lasting structure. 

Consult with the Maryland Soil Stabilization Experts at Gray & Son 

If you are concerned with the quality of the soil at your job site, don’t hesitate to consult with the experts. The team at Gray & Son has been providing quality service on soil stabilization projects for decades. We can help with determining the proper modifier and application rate, delivering modifiers, and mixing soils. To learn more about our process or to see how we can pave the way, check out our page on soil stabilization or call (410)-771-4311 today.