Methods of Soil Stabilization
You can see it no matter where you’re driving: road dust, potholes, washed out roads in desperate need of something to make them more, well, road-like. Paved and unpaved roads across the world suffer from similar problems. These exact issues are why soil stabilization exists.
What exactly is soil stabilization, and how does it fix road dust, potholes, or mud issues? Well, there are countless different ways to stabilize your roads, most of which can fall into one of three categories: chemical, mechanical, or enzyme based. We’ll break down what each of these are in a minute, for now we need to cover what exactly causes road dust and stability issues.
Common Road Issues
So, what causes road dust? Well, simply put, the smallest particles in the soil are being swept into the air from wind, animals, or cars driving around on the surface. Since these particles are so small, they have a harder time sticking to the rest of the soil, so they are very susceptible to physical interaction.
These soil particles are in most cases classified as clay, one of the three different soil types that can appear in your road soil. Unlike the other two types, silt and sand, clay is highly plastic when wet, meaning it can be molded or shaped (like pottery clay). Wet clay isn’t too difficult to deal with, but when you have a high amount of clay in your soil, and it gets too wet you can have serious issues with mud that leaves your road washed out and impassible during heavy rain. This feature is also what can lead to our next topic: potholes.
When clay absorbs a high amount of water, the soil expands. Through time and weather, the soil will begin to dry out, but that absence of water causes the soil to quickly shrink and leads to a separation in the road face displayed as cracks. If this is consistently happening to soil below the topcoat of a paved road, it can lead to a shifting of the subbase that tears apart the above chip seal or asphalt creating potholes.
We’ve covered what causes some of the most common road problems, great, now what? Well, now let’s look at how to fix these issues through different soil stabilization methods. It may be best to start with one of the most popular methods: chemical.
Chemical stabilization is pretty much what it sounds like: a chemical is applied to the road soil to help better bind the soil together, resulting in a harder, more dust resilient surface. The most common of the chemical stabilizers is magnesium chloride. Magnesium chloride is essentially salt, and it works by pulling moisture from the air and trapping it in the soil. This keeps the small particles heavy from moisture, so they are less likely to fly up when a car rolls on by.
As great as magnesium chloride is for dust suppression, it has quite a few downsides. Aside from being incredibly bad for the surrounding environment, the solution dissolves in water. This feature means that the road needs to be retreated every time it rains. Not only that, but due to natural erosion the treatment tends to wear off in 6-12 months.
Other chemical soil stabilizers can last longer but tend to be significantly more expensive. Cement/lime and Polymers are two stabilizers that work to bind the soil together in different ways.
Another soil stabilization method, that is an integral part of many other methods, would be mechanical. Using this method requires quite a bit of labor and machinery, so it can be expensive. It works by using intense impacts, either from a smooth wheel roller or a crane with a heavy weight attached to it. These impacts ripple through the soil, locking the soil particles in place and creating a smooth surface. This method was a popular choice, however with all the new advancements in soil stabilization technology it is now seldom used.
The last soil stabilization method uses enzymes. This enzyme-based soil stabilization method targets the clay in the soil, binding particles together on a molecular level. With the clay particles bound together, they are less affected by physical changes on the surface, such as wind or traffic. The molecular bond becomes so strong, in fact, that even water is unable to fully penetrate it, removing any mud issues. On top of solving most road issues, these solutions are generally safe for the environment.
Sound too good to be true? Well, there are a couple of downsides. For one, clay needs to be present in the soil for the enzymes to have something to react with. So, if your soil is more on the sandy side this solution might not be your best option.
So there you have it, three of the main soil stabilization methods. We’ve only just scratched the surface here, there are several options to choose from that fall into each of these categories. If you’re interested in learning more about all the other soil stabilization methods check out our soil stabilization page, where we go in-depth on each methods strengths and weaknesses, as well as the differences in soil types.