Popular in dust control and road stabilization, calcium chloride is a naturally occurring brine processed into a colorless, odorless liquid, and into white flakes or pellets. In most cases, a 38% solution of calcium chloride is best for both dust control and road stabilization. Less and it begins to lose its effectiveness; more and it tends to bead up on the road during application rather than penetrate the surface.

The Dow Chemical Company in Michigan makes LiquiDow 38% liquid calcium chloride, as well as solid versions. Guidelines recommend as little as two applications a year because the product resists evaporation. The company’s studies have shown that users can also cut aggregate loss by up to 80% and reduce total unpaved road maintenance costs by up to 33%.

For dust control, the chemical is hygroscopic, attracting moisture from the air and its surroundings. This keeps unpaved surfaces damp and dust down. It also exhibits a strong moisture film, high surface tension, and low vapor pressure that help bind aggregate particles together. Unpaved surfaces become — and remain — compacted. Over time, the chemical penetrates the surface several inches, adding a stabilizing effect to reduce frost damage and overall wear.

Dow says that calcium chloride is the only dust control material used to enhance road base stability. Whether building new roads or rehabilitating old ones — by conventional methods or the full-depth reclamation technique — calcium chloride’s contributions are the same. They include achieving greater density with less compactive effort, and achieving and maintaining optimum moisture content to avoid delays waiting for bases to dry out or for water to be added.

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Soil Stabilization Products Company, Inc. says its Road Oyl Resin Modified Emulsion is advanced emulsion technology. It’s a cold-applied, high-bonding-strength formulation of natural tree resin ingredients modified with a high fraction of resin, creating one of the most adhesive compounds ever derived from plant materials, the company says.

The product provides an environmentally friendly alternative to asphalt emulsions for general dust control requirements, and for prime coats, tack coats, seal coats, fog seals, and erosion and sediment control treatments. It’s also used as a pavement binder capable of producing cold-applied pavement mixtures with pavement stability values similar to hot-mix asphalt. The Resin Pavement mixtures formulated with the Road Oyl binder are in use for streets, trail surfaces, and other projects where natural appearances are important and the environment a concern.

The company’s EMC Squared System is concentrated liquid stabilizer technology formulated to increase the density, cementation, moisture resistance, frost heave resistance, bearing strength, shear strength, and stability of compacted earth materials. The highly concentrated products are simply added to the compaction water and applied as dilute solutions during the normal moisture addition and mixing operations used to bring aggregate and soil materials to optimum moisture content for compaction. The system is effective with a wide range of aggregate and recycled materials, as well as clay and silt soils.

A few of the agencies that have used the company’s system include TxDOT, Port of Los Angeles, Port of Oakland, and the USDA Forest Service. In fact, EMC Squared was used in the Coronado National Forest road project in Arizona featured on the cover of the February Better Roads.

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Coherex is a petroleum resin dust retardant product that is a concentrated, non-volatile emulsion consisting of about 60% semi-liquid natural petroleum resins and 40% wetting solution. The resins are film-forming, dust-binding portions; the wetting solution is the component that keeps the petroleum resin dispersed in finely divided particles and makes the product miscible with either fresh or salt water. Coherex is distributed by Golden Bear Oil Specialties in Arizona, and the company says that tests have shown Coherex to be both non-toxic and non-corrosive.

When it contacts the dusty ground, the product coats the dust particles and forms cohesive membranes that attach themselves to adjacent particles. The chain-like bonds result in large agglomerates too heavy to be dislodged by wind. The increase in particle size actually immobilizes the dust and prevents it from becoming airborne. Treatment with the product is a more effective approach to soil stabilization because the required cohesiveness is imparted to the soil without drastically altering its original makeup.

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Soiloc-D is an economical blend of acrylic resins used as a dust suppressant for roads and construction sites. It’s manufactured by Hercules Environmental, Inc. and supplied in a milky white, highly concentrated liquid that needs to be diluted with water before use.

Designed to be sprayed over exposed soil, sand, or fine gravel, it can be applied with standard water trucks or distributors. It’s environmentally safe. Soiloc-D is non-corrosive to metal and meets all requirements for non-asphaltic emulsions.

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Lyman Dust Control has a fleet of trucks fully equipped with state-of-the-art, computerized Bear Cat spreaders to serve all of the western states. Operators are qualified and fully trained. President Jerry Lyman says the company has been in the dust control business for over 25 years, offering experience and quality. A complete line of environmentally safe dust control products is on hand. Low-cost applications from Lyman to unpaved city and county roads have not only solved the dust problems, but have cut maintenance costs considerably, the company says.

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Presto Products Company’s Geoweb load support system confines cohesionless soils and produces a stiff base with high flexural strength, the company says. Under load, it generates high soil-to-cell wall friction, preventing shear failure and lateral movement of infill materials.

The Geoweb system improves the long-term load deformation performance of common fills and provides a load distribution system in three key areas: over weak soils; as a base for paved surfaces; and in surface stabilization for unpaved surfaces.

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PennzSuppress D, a dust suppressant and soil stabilizer from Pennzoil, is another product formulated with a petroleum resin base and an optimum blend of wetting agents, emulsifiers, and bonding agents. OSHA has classified the product as non-hazardous, and the company says it’s safe for people, animals, equipment, and the environment. Tests by the independent Midwest Research Institute show that the prescribed two-step application of PennzSuppress D retains a high level of effectiveness as an unpaved road dust suppressant.

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See Manufacturer Links Page for web links to suppliers.

Reprinted from Better Roads Magazine
May 2000