You can see it anywhere: soil that’s out of place and causing trouble. Maybe it’s dust blowing on the wind. An eroded hillside. A washboarded gravel road. A rutted drilling pad. Cracked, potholed pavement that belies the shifting soil underneath.
Soil is susceptible to erosion. And when you’re trying to build infrastructure, that won’t cut it. Thankfully, stabilization makes your soil stand up to the job you need it to do. The three main soil stabilization methods are mechanical, biological, and chemical. We’ll cover how they work and some soil stabilizers in each category. Then, we’ll wrap up with a look at Perma-Zyme, a unique soil stabilizer that combines all three methods to produce long-lasting and low-maintenance results.
Soil stabilization is the process of altering soil’s chemical or physical properties to achieve a specific goal—such as strengthening soil or preventing erosion. By changing soil’s properties so it won’t shift, engineers can safely use the soil to support the weight of infrastructure, such as roads, equipment pads, dams, and more.
Soil stabilization also reduces dust. Without it, these tiny particles can reduce visibility, cause accidents, damage property, and even kill plants. So, soil stabilization is essential to keep society—and the environment—safe and thriving.
The primary culprit behind unstable soil is erosion. Erosion weakens and wears away soil. Water erosion washes soil away; if an area loses enough soil, structures built on it can collapse. Wind erosion blows soil away. That’s what happened during the Dust Bowl in the 1930s: wind blew billions of tiny, dry soil particles into the air in huge dust clouds that devastated the landscape for hundreds of miles.
Weather can speed up erosion. Rain, freeze-thaw cycles, and extreme heat can all loosen and erode soil, causing potholes, cracks, washboards, and ruts to form. Topographical features accelerate erosion even more by either moving soil (as with bodies of water and fault lines) or making it easier for wind and rain to erode soil (as on steep hills).
However, some unstable soil doesn’t come from natural causes. Some erosion is manmade. High-volume, high-speed, or heavy traffic can weaken road surfaces or subbases. Poor design—such as inadequate drainage or overly steep grades—can also compound erosion.
Different types of soil are prone to different problems. Gravel can’t retain water or stick together like fine soils can. Sand lacks nutrient content, limiting plant growth, and fine sands are loose and likely to wash away. Silt’s high density and spherical particles make it hard to compact. Clay swells when wet and shrinks when dry, making it prone to cracks, and its tiny particles quickly dry out and become dust.
Each soil type requires different stabilization techniques to suit its unique properties. People have invented dozens of products to do this. But typically, they all use one of three methods: mechanical, chemical, or biological stabilization.
Mechanical stabilization alters soil’s physical properties by compacting, mixing, or containing it. The most common techniques—compaction and over excavation—rely on heavy machinery to do the job. Materials like aggregates and geosynthetics also aid in mechanical stabilization.
Compaction presses soil particles together to create a stronger surface that’s less likely to shift because the soil particles have less room to move. The three compaction techniques are static, vibratory, and dynamic.
Static compaction passes a roller or plate over the soil’s surface to push it into a tighter shape. With vibratory compaction, the machine rolls over the soil’s surface and “shakes” its particles closer together. And dynamic compaction repeatedly drops heavy weight on the soil.
There are over a dozen compacting machines. Dynamic compactors range from handheld rammers to huge cranes. Static and vibratory machines include everything from small tampers and plates that workers push along the ground to the massive padfoot and smooth wheel rollers you see on construction sites.
Compaction’s results last the longest when you pair them with another soil stabilizer, such as Perma-Zyme (more on that in a minute).
With over excavation, you aren’t just stabilizing soil; you’re replacing it. Excavator operators dig out unstable soil and put it into dump trucks, which export it from the jobsite. Once they reach stable soil or rock, they import new soil that will work better for the project and backfill the excavated area to the appropriate depth.
Over excavation is hard work, so it’s best to only remove as much soil as you absolutely have to to avoid unnecessary costs and labor. To that end, engineers sometimes leave some of the existing soil onsite and mix it with the new, imported material. This way, they can improve the soil’s properties while hauling less material.
Compaction and over excavation alone aren’t enough to stabilize soil long-term. Compacted soil eventually loosens and expands. As for over excavation, engineers can’t just dump loose soil into the ground; they have to stabilize it. So, these methods work best when you pair them with other stabilization efforts.
You can use a motor grader to shape soil, adding crowns and sloped shoulders to help the surface shed water. Improving drainage enables soil to stay compacted longer. Another option: use stabilizing materials like aggregate and geosynthetics.
The size of the area and soil particles helps determine which aggregate or geosynthetics you should use: larger areas with larger particles need larger soil stabilizers.
Chemical soil stabilization uses various compounds to bind soil particles together, resulting in a harder, more dust-resistant surface. Some chemical soil stabilizers include:
Lime is a chemical compound made of processed limestone rock that comes in dry or liquid form. The two main types of lime are hydrated and quicklime. Cement is another powdered chemical compound that contains limestone, clay, and other ingredients. There are numerous types of cement for different projects. Finally, fly ash is a byproduct of coal-burning power plants.
To use lime, cement, or fly ash, you must mix the material into the soil. It will then bind the particles together and harden them into a stronger, more durable surface. Using these materials requires the proper application technique and geotechnical testing to ensure that you’re using the correct product and amount.
Polymers are synthetic soil stabilizers that can work as binders (like lime and cement) or lubricants. Lubricant polymers act like soap by wetting soil particles so they move more easily into the positions they need to hold long-term.
Some polymers are injectable; engineers strategically insert them into key points in the soil. Polymer emulsions are topical solutions that work on the soil’s surface. Polymers’ lifespan varies dramatically depending on the type you use. Some types for building foundations last for over 100 years, while other types for road construction begin to break down after only 18-24 months.
Magnesium chloride is one of the most common chemical soil stabilizers due to its ability to suppress dust and harden soil’s surface. This road salt pulls moisture from the air into the soil, making the particles heavy so they’re less likely to fly into the air as dust when a car rolls by.
Mag chloride and its close relative, calcium chloride, are starting to fall out of favor due to environmental concerns.
Asphalt stabilization is the process of stabilizing soil so you can pave on top of it. Construction companies use various mechanical and chemical methods to achieve asphalt stabilization. But, asphalt itself is also a soil stabilizer. Asphalt and other pavements—such as concrete and chipseal—provide a hard shell that protects soil from erosion, distributes loads, and is stronger than soil alone.
We classify paving as a chemical soil stabilization technique because it contains a mixture of solid and liquid compounds that bind together to form a durable surface. In fact, concrete uses another chemical stabilizer, cement, as its main ingredient.
Bio means life, so biological soil stabilization involves using live soil stabilizers instead of inanimate objects like rocks or geosynthetics. In this case, people plant vegetation such as trees, shrubs, grass, or flowers. The plants’ root systems weave together to help hold soil in place and prevent erosion.
Of course, you can’t put plants everywhere. (An airport runway would be a terrible spot for a tree, after all.) That’s why biological soil stabilization works best for things like slopes or sensitive ecosystems, including forests, parks, and wetlands.
Choosing the right plants can both stabilize soil and also improve the quality of the environment. For example, planting native tree species can aid in reforestation while feeding and sheltering wildlife. As these symbiotic relationships begin to flourish, the ecosystem’s overall health improves—and there’ll be less erosion. That’s a win-win!
Perma-Zyme is a biochemical soil stabilizer. It’s made of enzymes, which are proteins that come from living organisms, so it’s 100% natural. It’s also entirely organic, non-toxic, and non-corrosive, making it stand out from traditional chemical soil stabilizers.
Once the enzymes in Perma-Zyme mix with the soil, people compact it to achieve maximum durability and strength. The enzymes then chemically react to bind the particles together into a hard, concrete-like surface. So, Perma-Zyme uses all three methods to stabilize your soil: mechanical, chemical, and biological.
Perma-Zyme treated surfaces last 10+ years in most settings with little to no maintenance, saving you time and money. It also significantly reduces dust for up to two years with no chloride treatments.
There you have it, the three main soil stabilization methods and one soil stabilizer that combines them all! Now that you’ve got the basics covered, it’s time to decide which soil stabilizer(s) to use for your next project.
To help you do that, we’ve weighed the pros and cons of all the techniques we covered in this blog. We looked at factors such as cost, lifespan, durability, and eco-friendliness, so you can find the best fit for your budget and project.
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