Lignins: A Safe Solution for Roads
Lignosulfonates have a long history of use on roads as a method for dust control and surface stabilization. Lignosulfonate road products are derived from the lignin that naturally binds cellulose fibers together to give trees and plants firmness. These products are a safe and economical alternative to petroleum and salt-based products that are also applied to road surfaces.
The original method of applying lignosulfonates to road surfaces for dust control was very simple: dilute raw lignosulfonate solutions were sprayed in light applications onto dirt roads. Over time, road surfaces began to show an improved stabilization, increasing the appeal of using lignosulfonates. Lignosulfonate is well suited for a variety of uses such as parking lots, driveways, and road shoulders, where pavement is too costly and dust conditions become intolerable.
Lignosulfonates have a natural adhesive property when moist. When applied to dirt roads, the lignosulfonate solution coats individual road particles with a thin adhesive-like film that binds the particles together. It acts as a dispersant, allowing the particles to pack closer together for a stronger surface. Consequently, water uptake by the road bed surface is greatly reduced and the binder is less likely to be washed away by rain.
Benefits of Lignosulfonates for Road Applications:
- Creates a Denser, Firmer Road Cap - Lignosulfonate treatment eliminates the sliding hazards of loose dirt and gravel by binding them into a hard, skid-resistant surface.
- Safe for the Environment - Lignosulfonates are non-toxic when properly applied, making them safe for foilage and surface water surrounding roadways.
Lignosulfonates are not corrosive like other dust control products and can be applied without special equipment or clothing.
- Improves Safety - By controlling dust clouds, visibility on dirt roads is significantly increased, adding to driving comfort and safety.
- Improves Efficiency - Vehicles can travel over roads treated with lignosulfonates almost immediately, eliminating the need to re-route traffic. Dust is less likely to enter engine parts, reducing equipment maintenance requirements.
- Reduces Road Repairs - Hardened road surfaces are less likely to suffer the
ribbed "washboard" effect common with untreated gravel or dirt roads. As a result, frequent grading can be reduced or eliminated.
|
Commercial lignosulfonate products meet the specifications of the U.S. Forest Service Administration, General Service Administration and local and regional government standards. Lignosulfonate use on roads has been endorsed by various agencies for decades.
| Recommendations for Effective Application |
Lignosulfonates for road applications are usually shipped in a concentrated solution and diluted with water on the job site to about a 25 percent solids content. Road conditions and climate can affect the application rate. However, as a general rule for dust control, a diluted solution of lignosulfonate is applied at a rate of one-half gallon per square yard. Stabilization of the road surface normally requires one gallon of lignosulfonate solution per square yard applied to a depth of six inches.
The Lignin Institute has developed recommendations for the safe and effective application of lignin products to raod surfaces.
The Lignin Institute Recommends That:
- Equipment used to transport lignin products should be clean and free of any contaminating residue.
-
Water used to dilute lignin should not contain residues or other contaminants.
-
The extent of dilution and the application rate should be carefully considered for the intended function.
-
Prudent consideration should be given to weather, soil and surrounding conditions.
|
The Lignin Institute has also established voluntary product quality standards for lignin products (including calcium, ammonium and sodium lignosulfonates) used for road and soil stabilization. Lignin products must also meet all applicable regional, state, and federal requirements for products applied to road surfaces. The standards, which list recommended maxium levels of various components used in lignosulfonate solutions, are available by contacting the Lignin Institute. |
