Polymer soil stabilizers prevent erosion by holding soil in place, lubricating it to improve compaction, or binding its particles together, so they’re a solution for some soil stabilization projects.
However, while polymers work well on some projects, they also have their pitfalls. They can be expensive and may rip, clog, or wear off over time. And many are synthetic materials. So, some people are concerned about polymer soil stabilization’s costs, lifespan, and environmental effects.
In this article, we’ll recap what polymers are and the three main polymer soil stabilization methods. Then, we’ll compare these options to seven other soil stabilizers that work similarly:
Let’s get started!
We’ve talked about polymer soil stabilization in detail before, so let’s hit the highlights here.
Polymers are long, repeating molecule chains that make up countless natural and manmade objects, including everything from cotton threads to your muscles to PVC pipes. Polymer soil stabilizers are special polymers that people use to prevent soil erosion.
Like any polymer, polymer soil stabilizers can be synthetic, or they can come from natural products. The latter, called biopolymers, can be more eco-friendly than some traditional soil stabilization methods.
The three main polymer soil stabilization methods are geotextiles, emulsions, and chemical injections.
Geotextiles are polymeric fabrics that hold soil in place. They can be natural or synthetic, so some eco-friendly options are available. On the downside, they may rip or clog if overburdened or misused.
Polymer emulsions are polymers mixed with water. They lubricate the soil’s surface so it’s easier to compact, and they help bind the soil particles together for better results than compaction alone. However, many emulsions contain plastics, and they may be prone to wash or wear off after a few months.
Some foam or liquid polymers don’t just go on top of the soil; they go in it. Injectable foam polymers work well for stabilizing soil under existing foundations and roads. This method is helpful if you’ve already got infrastructure in place that you don’t want to rip up, but it can get pricey. Plus, they typically last less than two years.
Polymer soil stabilizers are effective for many projects. But as we mentioned, their high costs and tendency to wear off are pushing many counties and companies to look for alternatives. On top of that, they’re shifting toward soil stabilization methods that are more sustainable than polymers amid growing environmental concerns.
Aggregate is processed, uniformly sized rocks that work similarly to geotextiles to improve drainage and keep soil from washing away.
Aggregate is versatile and works almost anywhere—on slopes, on roads, under roads, under buildings, in drainage areas, and so forth. Almost every project in the U.S. uses some aggregate for soil stabilization and strength. Aggregate is made from rocks, so it’s natural and won’t contaminate soil and water.
Anyone who’s lived on a gravel road knows aggregate is still prone to erosion. Rain, snowmelt, and traffic can carry aggregate off exposed surfaces. Or, vehicle tires can work aggregate deeper into the dirt so that it disappears. You could find yourself spending a small fortune re-graveling these areas.
Plants are effective soil stabilizers because their roots knit together underground to help hold soil in place—much like geotextiles weave together to prevent erosion.
Plants work especially well for slope control and drainage areas. Their roots help absorb water and stem its flow, minimizing erosion. That’s one reason landfills often plant grass over mounds of garbage!
Plants are all-natural, so they’re generally eco-friendly options. Of course, if eco-friendliness is your concern, it’s wise to buy plants from a reputable supplier and use native species.
Plants don’t work everywhere. After all, you can’t just plop some trees down in the middle of a road or under a building. So, you’ll typically plant vegetation alongside infrastructure as a secondary soil stabilization method—not as a first line of defense.
Large plants may grow enormous root systems that upheave or crack roads and foundations. Or, they may obstruct drivers’ views. Both are safety hazards for people using these structures.
Water works to lubricate soil and enable compaction. So, it’s like a polymer emulsion minus the binding properties.
Water is a 100% natural way to moisten soil to aid in compaction. It’s easy to apply and non-hazardous, which is why it’s one of the most popular dust control solutions for companies and counties, especially when treating small areas.
Natural and eco-friendly aren’t always the same. In some places, water is plentiful and easy to access, but in dry regions, using thousands of gallons of water to constantly suppress dust is wasteful at best and unsustainable at worst.
Plus, water only works to facilitate compaction and suppress dust. It can’t truly stabilize soil in and of itself. And it’s only effective for a short time—up to two days if you’re lucky, but usually only a few hours.
Like polymer emulsions, bitumen emulsions both lubricate and bind soil particles together for an extra firm surface. So, what’s bitumen? It’s little pieces of asphalt.
Bitumen emulsions offer a “happy medium” between polymers and paving, at a fraction of the cost of paving. They’re generally effective and easy to apply since you spray them onto the soil’s surface.
Bitumen is small chunks of asphalt, aka petroleum. Those particles can wash into nearby soil and streams, building up and contaminating the area over time. Bitumen emulsions are especially prone to washing away if it rains shortly after application.
Another problem is transportation and storage prior to use. The ingredients in bitumen emulsions can separate before reaching the jobsite, so many manufacturers use additives like calcium chloride to stabilize the mixture—which can also be environmentally harmful.
Lime is made from heat-treated limestone. It’s a powerful, popular binding agent that also hardens soil particles. You can purchase dry, powdered lime, or liquid lime slurry.
Lime is a highly effective soil stabilization method that people have used for thousands of years. Mixing it into the soil has the distinct advantage of hardening the soil itself—something polymers won’t do. And once it’s mixed into the soil, it’s there to stay. You don’t have to worry about this soil stabilizer wearing off!
If lime was good enough for the ancient Egyptians, why wouldn’t it be good enough for us? For starters, lime can be costly if you don’t live near a limestone source. And the price goes up when you factor in the cost of ripping up the soil, mixing in the lime, and re-compacting it all. It’s also difficult to use lime under pre-existing structures, since you can't inject it like certain polymers.
Cement is a manmade soil stabilizer. While its ingredients vary from one mix to the next, they can include lime, chalk, silica, iron ore, clay, and gravel. Like lime, cement binds and hardens soil.
Cement is one of the most popular soil stabilizers for all types of construction projects. It makes soil extremely hard and strong, so it can withstand water, wind, traffic, and certain chemicals. Cement is especially effective for building foundations and paved road subbase.
Depending on your location, cement may cost more than lime, and treating an unpaved road with cement can be cost-prohibitive. Additionally, cement can be brittle and doesn’t resist all chemicals. Chloride road salts, dust suppressants, and even decomposing leaves can corrode it.
Perma-Zyme is an enzyme-based soil stabilizer that chemically reacts with clay and limestone in soil to permanently bond its particles together into a hard, concrete-like surface.
One of the biggest perks of Perma-Zyme is its lifespan. Unlike polymers that last six to 18 months, a single Perma-Zyme application creates a hard surface that can last more than 10 years on an unpaved road and more than 30 years on a paved road. It’s 100% organic, non-toxic, and non-hazardous, so it’s safe for crews and the environment.
Perma-Zyme also requires little to no maintenance, meaning you can save thousands of dollars on maintenance costs over the lifespan of your project.
Perma-Zyme creates a hard, concrete-like surface and eliminates most erosion, but it doesn’t make unpaved areas perfectly smooth like asphalt. A gravel road will still feel like a gravel road; it’ll just be a much more stable one!
There are also some requirements for a successful application. You’ll need to wait until temperatures are between 40°F and 115°F, with no rain for at least 72 hours after application. And since it works best on clay and limestone soils, you may need to import more compatible material before applying it to sandy or silty soils.
When choosing a soil stabilizer, you’re looking for the product that will give you the optimal combination of effectiveness, longevity, cost savings, and sustainability. And sometimes, that means choosing the right combination of soil stabilizers.
Maybe you use plants and geotextiles to stabilize a drainage area near your project. Maybe you opt to treat your road’s subbase only with cement. Maybe you treat a dirt road with Perma-Zyme and add a gravel topcoat for traction.
Whatever you choose, remember to prioritize your goals at the beginning. Knowing what's most important to you will help you weigh your options efficiently and avoid costly reapplications. We hope this helps you with your choice!
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