You can see it no matter where you drive: dust, cracked surfaces, potholes, and washboards in desperate need of something to make the road feel more like, well, a road. These problems occur on both paved and unpaved roads due to lack of proper soil stabilization. The first step toward solving them is understanding the types of soil stabilization you can use.
Let’s walk through the three main soil stabilization methods: biological, chemical, and physical. We’ll discuss some soil stabilizers that fit into each category and how they work. But first, let’s cover two common soil issues, instability and dust, as well as what causes them.
Soil issues typically stem from erosion. Erosion weakens and wears away soil, creating a host of problems. Two of the most common ones—especially for unpaved roads—are instability and dust.
Soil becomes unstable due to factors such as weather, topography, traffic, road design, and soil type.
Freeze-thaw cycles, rain, heat, sun, and humidity can all loosen and erode soil, causing potholes, cracks, washboards, and ruts. Topographical features like steep hills, water, and underground fault lines then accelerate that erosion.
Traffic and road design factors that can prematurely weaken road surfaces or subbases include:
Finally, soil type plays an important role in stability (or lack thereof), as some soils are more susceptible to erosion than others. Silt and fine sands erode easily because the particles are small and loose, while clay resists erosion because its particles stick together. However, clay has its own problems. It’s highly plastic when wet, meaning you can mold or shape it like Play-Doh. That’s good when you need to compact clay that contains the ideal amount of moisture, but oversaturated clay becomes so gooey that it’s impassable. When it dries out, clay shrinks, creating cracks that can develop into serious potholes or cause subbases to shift.
Road dust’s cause is simple: small soil particles dry out, then wind and traffic blow them into the air. Since these particles are so miniscule and have little—if any—moisture to weigh them down, they have a harder time sticking to the rest of the soil.
Road dust particles may be tiny, but they have a huge impact. Excessive road dust reduces visibility, which can lead to fatal accidents. It also damages property and can even kill plants. Find out more about the surprising reasons why we need road dust control.
Whether you’re struggling with road dust or unstable soil, the solution to these problems is the same: soil stabilization. The three main methods are biological, chemical, and physical (sometimes called mechanical) soil stabilization. Let’s explore each one.
Biological soil stabilization is typically the most eco-friendly soil stabilization method for hardening soil and preventing erosion. It relies on living organisms like plants or substances derived from living organisms, such as enzymes.
Plants are good at preventing erosion because their roots hold soil in place. Their foliage and flowers also offer environmental benefits and can help restore struggling ecosystems, provided you choose species native to your area.
Enzyme soil stabilizers like Perma-Zyme chemically react with soil particles, binding them together on a molecular level to create a hard, concrete-like surface. In Perma-Zyme’s case, this process makes the soil nearly impenetrable to water, preventing mud and erosion for 10 years or more.
During chemical soil stabilization, crews apply a compound to help bind soil particles together, resulting in a harder, more dust-resistant surface. Chemical soil stabilization methods are common because these products are widely available. Some options include:
For lime, cement, and polymers, you can rip up the soil and mix the stabilizer into it. Or, you can inject certain types of these products directly into the soil, so there’s less disturbance at the surface. Meanwhile, you can only apply asphalt and chlorides to the soil’s surface.
Magnesium chloride and calcium chloride are two of the most common chemical soil stabilizers. These road salts pull moisture from the air into the soil, making the particles heavy so they are less likely to become dust that flies up when a car rolls by. They also help create a hard crust over the soil’s surface. However, they wear off after a few months, so treated areas typically require at least two applications per year.
Physical soil stabilization uses both objects and mechanical methods to contain and compact soil. Some of these are:
Aggregates are processed rocks, while geotextiles are woven nets typically made from cloth, fabric, or plastic. You can apply both of them to the soil’s surface or embed them in the soil to help hold it in place. The size of the area and soil particles help determine the size of aggregate or geotextile mesh you should use: larger areas with larger particles need larger soil stabilizers.
Compaction and over-excavation are both mechanical soil stabilization methods. They require a lot of labor and machinery, so they can be expensive. Vibratory compaction uses a compacting machine that rolls over the soil’s surface and “shakes” it into place, while dynamic compaction uses a crane that repeatedly drops a heavy weight on the soil. Over-excavation requires digging up unstable soil and replacing it with more stable soil, which you’ll then compact.
There you have it, the three main soil stabilization methods! Now that you’ve got the basics covered, it’s time to decide which soil stabilizer—or stabilizers—are right for you.
