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Dust Control and Base Stabilization with Liquidow Calcium Chloride

This article reviews the basic guidelines for applying calcium chloride to any unpaved surfaces in order to achieve dust control or base stabilization. It also recommends procedures for bringing an unpaved surface up to standard, as well as converting unpaved surfaces from petroleum- or lignin-based products to calcium chloride.

Keep in mind, however, this article is intended as a guide only. Varying factors such as local traffic patterns, soil conditions, and weather may indicate the need for increased or decreased application rates or different work procedures.

Before reviewing the details of calcium chloride applications and maintenance procedures, it may be helpful to provide a brief refresher on what the chemical does and how it does it.

How calcium chloride controls dust

Calcium chloride helps control dust because it is a hygroscopic material. This means it attracts moisture from the atmosphere and environment. When calcium chloride is spread on an unpaved surface, it keeps it damp thus keeping dust down.

What’s more, calcium chloride resists evaporation. This means it continues drawing moisture from its surroundings – and to keep dust down – for long periods – even on hot, dry days.

How calcium chloride provides base stabilization

In addition to being hygroscopic and resisting evaporation, calcium chloride also has a strong moisture film, high surface tension, low vapor pressure, and low freezing point.

When mixed with aggregate before blading and shaping, calcium chloride helps retain moisture and bind the dust particles together. This is critical because it means during compaction maximum density can be achieved with less compactive effort. And because of the chemical’s low freezing point, it helps protect the unpaved surface against frost heave in winter.

It should also be noted that a continual practice of dust control with calcium chloride will provide base stabilization. That’s because the chemical will work its way through the surface over time and into the base several inches to consolidate the soil.

The results of a successful program

No matter whether you choose to only control dust or to provide base stabilization as well, you’re on your way to a better unpaved surface that will remain hard, smooth, and dust-free for a longer period of time. And it will be very inexpensive to maintain.

That’s because surfaces which once required weekly or semi-weekly bladings typically will now need bladings only once every eight to twelve weeks.

What’s more, when you choose to provide dust control and base stabilization, you take a big step toward lower construction costs later. That’s because by improving surface and base quality, calcium chloride will help reduce the amount of preparation needed when the surface is ready for paving.

In short, calcium chloride is not only a step up in unpaved road quality; it’s a step toward lower total maintenance and construction costs too.

It should be noted, however, that calcium chloride cannot make a bad road good. Therefore, the recommendations shown on the following page should be followed to assure best results.

General Maintenance Guidelines and Procedures

It should be noted that local conditions will affect construction and maintenance procedures to a great degree. Any dust control or stabilization technique that’s recommended must be reviewed while taking these conditions into account. But as a first step, here are general guidelines for construction practices when using calcium chloride.

Drainage and Shaping

Adequate drainage is very important. Ditches and culverts should be reshaped and cleaned or replaced where necessary. Shoulders should be bladed down so water can’t be trapped. Remove all sod berms and grass which prevent free drainage. Final surface shaping should be in a manner which will permit water to drain off it properly and thereby eliminate ponding. Final road shaping should follow a modified “A” type crown with a slope of at least ½” per linear foot.

Aggregate selection

To achieve the best dust control and stabilization results, it is suggested the average gradation mix be used as a guide. The material specified should contain sufficient moisture to ensure compaction to design density. And when needed, incorporate any fines from the shoulder into the road mixture.

Aggregate placement

Aggregate material should be distributed evenly from a moving truck spreader box or a powered spreading machine. Do not dump aggregate material upon the surface. If the material is placed in windrows, spread by blading.

Recommendations for Using Calcium Chloride

What form of calcium chloride to use?

The decision to use liquid or dry calcium chloride is usually based on economic considerations and the type of storage, mixing, and application equipment available.

Liquid calcium chloride is the preferred product because you’re better assured of more even distribution of the chemical. LIQUIDOW&™ brand liquid calcium chloride can be purchased in a 30-42% solution or users can sparge (mix with water) DOWFLAKE XTRA&™ or PELADOW&™ brand solid calcium chloride products on location to produce a liquid.

DOWFLAKE XTRA&™ or PELADOW&™ calcium chloride can also be spread directly onto unpaved surfaces without first being put into a solution. Special consideration must be taken to make sure adequate moisture is available to the dry calcium chloride. This is usually accomplished by adding water to the unpaved surface, before or after the calcium chloride has been applied.

When to use it

Unpaved surfaces should normally be treated with calcium chloride during the spring after seasonal rains, and while moisture still remains in the ground. However, applications should not be started during a heavy rainfall or if rain is threatening. A light mist is helpful, provided the moisture can soak into the ground and not run off.

Unpaved Roads

As a rule of thumb, one car making one pass on one mile of untreated unpaved road every day can generate one ton of dust in one year. When this road is treated with calcium chloride, however, it will retain a high percentage of the fines it would otherwise lose.

The calcium chloride application rates shown below for both dust control and base stabilization are standard. For heavily travelled roads, you may want to increase these rates slightly.

Dust Control

  1. Blade and shape the surface to a straight line slope of ½” to 12” – a type “A” crown. This will permit water to drain off it properly and thereby eliminate ponding.
  2. Apply a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard.
  3. Dust control is usually maintained throughout the summer with minimal attention. However, for best results a second treatment is recommended in late summer or early fall. Follow the application rates given in Step 2. Reblade, if necessary, according to Step 1.

Base Stabilization

  1. Base stabilization requires a total of 0.6 gallons of liquid calcium chloride per square yard: 0.4 gallons are used for stabilization; 0.2 gallons are used as a top dressing. Scarify the road surface to a depth that will remove all potholes and other irregularities – a minimum of 6”.
  2. If it is necessary to add aggregate to improve the soil gradation, a combination of materials that is comparable to those already in place should be used. If the materials will be road mixed at the work site, the new material should be placed on the roadway before applying the calcium chloride. No more than six inches of loose aggregate should be placed in a layer.
  3. If it is unnecessary to add aggregate, a 38% solution of LIQUIDOW calcium chloride should be applied uniformly to the scarified material at a rate of 0.4 gallons per square yard. Or apply 2.50 pounds of DOWFLAKE XTRA or 1.95 pounds of PELADOW per square yard.
  4. Uniformly mix the soil, new aggregate (if added), and calcium chloride, plus water (if necessary). Mixing should begin as soon as possible after the calcium chloride is applied. The mix depth is the same as the scarification depth. When road mixing, the materials can be mixed by blading.

    If a travelling rotary mixer is used, it should be able to separate the soil particles without fracturing them and, at the same time, disperse the calcium chloride evenly. An alternative method to road mixing is plant mixing. Plant mixing the materials assures a more uniformly blended mixture and less chance for material segregation. After the material is thoroughly mixed, it can be hauled to the site and placed on the roadway using a mechanical spreader.

  5. Blade, shape, and compact the surface to a straight line slope of ½” to 12” – a type “A” crown. This will permit water to drain off properly and thereby eliminate ponding.
  6. Top dress the road by applying a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.2 gallons per square yard. Or apply 1.25 pounds of DOWFLAKE XTRA or 0.97 pounds of PELADOW per square yard.
  7. Once the road is stabilized, dust control is usually maintained throughout the summer with minimal attention. However, for best results a second top dressing is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 5.

Mining Haul Roads, Logging Roads, and Other Heavy Industrial Roads

Perhaps no other roads take more of a pounding than logging and mining haul roads. Heavily loaded trucks travelling at high rates of speed can tear apart these roads, leading to frequent maintenance and high costs.

Therefore, it’s recommended that the application rate of calcium chloride be increased over the standard rate of 0.27 gallons per square yard when practicing dust control, as shown below. Also, you may want to compact the aggregate more firmly on curves to help keep the material in place.

Dust Control

  1. Blade and shape the surface to a straight line slope of ½” to 12” – a type “A” crown. This will permit water to drain off it properly and thereby eliminate ponding.
  2. Apply a 38% solution of LIQUIDOW calcium chloride to the road surface in two passes so that the total rate applied to the road is 0.35 gallons per square yard. Or apply 2.20 pounds of DOWFLAKE XTRA or 1.71 pounds of PELADOW per square yard.
  3. Dust control is usually maintained throughout the summer with minimal attention. However, for best results a second treatment is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 1.

Base Stabilization

  1. Base stabilization requires a total of 0.6 gallons of liquid calcium chloride per square yard: 0.4 gallons are used for stabilization; 0.2 gallons are used as a top dressing. Scarify the road surface to a depth that will remove all potholes and other surface irregularities – a minimum of 6”.
  2. If it is necessary to add aggregate to improve the soil gradation, a combination of materials that is comparable to those already in place should be used. If the materials will be road mixed at the work site, the new materials should be placed on the roadway before applying the calcium chloride. No more than six inches of loose aggregate should be placed in a layer.
  3. If it is unnecessary to add aggregate, a 38% solution of LIQUIDOW calcium chloride should be applied uniformly to the scarified material at a rate of 0.4 gallons per square yard. Or apply 2.50 pounds of DOWFLAKE XTRA or 1.95 pounds of PELADOW per square yard.
  4. Uniformly mix the soil, new aggregate (if added), and calcium chloride, plus water (if necessary). Mixing should begin as soon as possible after the calcium chloride is applied. The mix depth is the same as the scarification depth. When road mixing, the materials can be mixed by blading.

    If a travelling rotary mixer is used, it should be able to separate the soil particles without fracturing them and, at the same time, disperse the calcium chloride evenly. An alternative method to road mixing is plant mixing. Plant mixing the materials assures a more uniformly blended mixture and less chance for material segregation. After the material is thoroughly mixed, it can be hauled to the site and placed on the roadway using a mechanical spreader.

  5. Blade, shape and compact the surface to a straight line slope of ½” to 12” – a type “A” crown. This will permit water to drain off it properly and thereby eliminate ponding.
  6. Top dress the road by applying a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.2 gallons per square yard. Or apply 1.25 pounds of DOWFLAKE XTRA or 0.97 pounds of PELADOW per square yard.
  7. Once the road is stabilized, dust control is usually maintained throughout the summer with minimal attention. However, for best results, a second top dressing is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 5.

Trucking Terminals and Parking Lots

Because drivers frequently make sharp turns and turn-arounds in parking lots and particularly trucking terminals, you may want to increase the standard application rate of 0.27 gallons of calcium chloride per square yard when practicing dust control, as shown below.

Dust Control

  1. Blade and shape the surface in a manner that will permit water to drain off it properly and thereby eliminate ponding.
  2. Apply a 38% solution of LIQUIDOW calcium chloride to the surface at a rate of 0.3 gallons per square yard. Or apply 1.87 pounds of DOWFLAKE XTRA or 1.46 pounds of PELADOW per square yard.
  3. Dust control is usually maintained throughout the summer with minimal attention. However, for best results a second treatment is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the unpaved surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 1.

Base Stabilization

  1. Base stabilization requires a total of 0.6 gallons of liquid calcium chloride per square yard: 0.4 gallons are used for stabilization; 0.2 gallons are used as a top dressing. Scarify the road surface to a depth that will remove all potholes and other surface irregularities – a minimum of 6”.
  2. If it is necessary to add aggregate to improve the soil gradation, a combination of materials that is comparable to those already in place should be used. If the materials will be road mixed at the work site, the new materials should be placed on the roadway before applying the calcium chloride. No more than six inches of loose aggregate should be placed in a layer.
  3. If it is unnecessary to add aggregate, a 38% solution of LIQUIDOW calcium chloride should be applied uniformly to the scarified material at a rate of 0.4 gallons per square yard. Or apply 2.50 pounds of DOWFLAKE XTRA or 1.95 pounds of PELADOW per square yard.
  4. Uniformly mix the soil, new aggregate (if added), and calcium chloride, plus water (if necessary). Mixing should begin as soon as possible after the calcium chloride is applied. The mix depth is the same as the scarification depth. When road mixing, the materials can be mixed by blading.

    If a travelling rotary mixer is used, it should be able to separate the soil particles without fracturing them and, at the same time, disperse the calcium chloride evenly. An alternative method to road mixing is plant mixing. Plant mixing the materials assures a more uniformly blended mixture and less chance for material segregation. After the material is thoroughly mixed, it can be hauled to the site and placed on the roadway using a mechanical spreader.

  5. Blade, shape and compact the surface to a straight line slope of ½” to 12” – a type “A” crown. This will permit water to drain off it properly and thereby eliminate ponding.
  6. Top dress the road by applying a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.2 gallons per square yard. Or apply 1.25 pounds of DOWFLAKE XTRA or 0.97 pounds of PELADOW per square yard.
  7. Once the road is stabilized, dust control is usually maintained throughout the summer with minimal attention. However, for best results, a second top dressing is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the road surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 5.

Shoulders, Construction Sites, Rail Yards, Landfills and Other Unpaved Surfaces

Besides being a nuisance, dust can reduce visibility and create hazardous conditions for vehicle and equipment operators. This, of course, can increase the chance for accidents. Dust is probably responsible for more vehicle maintenance and machine breakdowns than is often realized, too. What’s more, it can also be the cause of higher cleaning and maintenance costs both inside and outside of buildings.

In other words, dust can be costly. But controlling it with calcium chloride really isn’t. And when you stabilize the base courses with calcium chloride, you’re really investing in lower total maintenance and construction costs while providing better quality unpaved surfaces.

Dust Control

  1. Blade and shape the surface in a manner that will permit water to drain off it properly and thereby eliminate ponding.
  2. Apply a 38% solution of LIQUIDOW calcium chloride to the surface at a rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard.
  3. Dust control is usually maintained throughout the summer with minimal attention. However, for best results a second treatment is recommended in late summer or early fall. Follow the application rates given in Step 2. Reblade, if necessary, according to Step 1.

Base Stabilization

  1. Base stabilization requires a total of 0.6 gallons of liquid calcium chloride per square yard: 0.4 gallons are used for stabilization; 0.2 gallons are used as a top dressing. Scarify the road surface to a depth that will remove all potholes and other surface irregularities – a minimum of 6”.
  2. If it is necessary to add aggregate to improve the soil gradation, a combination of materials that is comparable to those already in place should be used. If the materials will be road mixed at the work site, the new materials should be placed on the roadway before applying the calcium chloride. No more than six inches of loose aggregate should be placed in a layer.
  3. If it is unnecessary to add aggregate, a 38% solution of LIQUIDOW calcium chloride should be applied uniformly to the scarified material at a rate of 0.4 gallons per square yard. Or apply 2.50 pounds of DOWFLAKE XTRA or 1.95 pounds of PELADOW per square yard.
  4. Uniformly mix the soil, new aggregate (if added), and calcium chloride, plus water (if necessary). Mixing should begin as soon as possible after the calcium chloride is applied. The mix depth is the same as the scarification depth. When site mixing, the materials can be mixed by blading.
  5. Blade, shape and compact the surface in a manner that will permit water to drain off it properly and thereby eliminate ponding.
  6. Top dress the surface by applying a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.2 gallons per square yard. Or apply 1.25 pounds of DOWFLAKE XTRA or 0.97 pounds of PELADOW per square yard.
  7. Once the surface is stabilized, dust control is usually maintained throughout the summer with minimal attention. However, for best results, a second top dressing is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the unpaved surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 5.

Converting Unpaved Surfaces from Petroleum- or Lignin-Based Products to Calcium Chloride

Calcium chloride does not mix with petroleum- or lignin-based products just as water does not. So unpaved surfaces treated with these materials require special considerations.

It is strongly recommended that the stabilization guidelines presented below are followed in order to increase surface life as well as control dust.

Dust Control

  1. Scarify the surface to a depth sufficient to break up the petroleum- or lignin-impregnated crust as well as to bring the untreated soil to the surface. Typically this will be 6”.
  2. Windrow or pulverize the soil to break up any large lumps of crusted material and to provide a thorough mix.
  3. Blade, shape, and compact the surface in a manner that will permit water to drain off it properly and thereby eliminate ponding. For unpaved roads, this will generally be a straight line slope of ½” to 12” – a type “A” crown.
  4. Apply a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard.
  5. Dust control is usually maintained throughout the summer with minimal attention. However, for best results a second treatment is recommended in late summer or early fall. Follow the application rates given in Step 4. Reblade, if necessary, according to Step 3.

Base Stabilization

  1. Base stabilization requires a total of 0.6 gallons of liquid calcium chloride per square yard: 0.4 gallons are used for stabilization; 0.2 gallons are used as a top dressing. Scarify the unpaved surface to a depth sufficient to break up the petroleum- or lignin-impregnated crust as well as bring untreated soil to the surface. Typically this will be 6”.
  2. Uniformly apply a 38% solution of LIQUIDOW calcium chloride to the scarified surface at a rate of 0.4 gallons per square yard. Or apply 2.50 pounds of DOWFLAKE XTRA or 1.95 pounds of PELADOW per square yard.
  3. Windrow or pulverize the soil to further break up the petroleum or lignin crust and mix in the calcium chloride.
  4. Blade, shape and compact the surface in a manner that will permit water to drain off it properly and thereby eliminate ponding. For unpaved roads, this will generally be a straight line slope of ½” to 12” – a type “A” crown.
  5. Top dress the surface by applying a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.2 gallons per square yard. Or apply 1.25 pounds of DOWFLAKE XTRA or 0.97 pounds of PELADOW per square yard.
  6. Once the surface is stabilized, dust control is usually maintained throughout the summer with minimal attention. However, for best results a second top dressing is recommended in late summer or early fall.

    Apply a 38% solution of LIQUIDOW calcium chloride to the surface at the rate of 0.27 gallons per square yard. Or apply 1.69 pounds of DOWFLAKE XTRA or 1.32 pounds of PELADOW per square yard. Reblade, if necessary, according to Step 4.

Of course there is so much more to learn about calcium chloride and how your overall road program can benefit from this versatile chemical. Don’t forget about its beneficial use for snow and ice control as well.