Road Treatment – Information about Calcium Chloride

Road Treatment – Information About Calcium Chloride

Calcium chloride outdistances traditional deicing materials to achieve safer, bare pavement – faster than salt or abrasives alone. Calcium chloride melts up to eight times as much ice as does salt alone – within the first 30 minutes at 20F (-7C) following application. Premixed with salt and abrasives, calcium chloride becomes a cost-effective edge for winter road safety.

PROPERTIES

• Exothermic: calcium chloride releases heat as it melts to speed salt’s melting ability.
• Hygroscopic: calcium chloride attracts moisture and dissolves quickly to activate rock salt’s melting action.
• Fast Acting: calcium chloride begins to dissolve immediately upon application to break the bond between pavement and ice.
• Powerful: calcium chloride brine remains active for prolonged periods of time to prevent ice from bonding to the highway.
• Low Eutectic Point: calcium chloride melts to much lower temperatures than salt; controlled studies prove its effectiveness down to -59F (-51C)

BENEFITS

• Highway Safety: studies show that in 85% of applications, calcium chloride/salt mixtures achieve bare pavement faster than salt alone at temperatures near 30F (-1C) to ease traffic and reduce accidents.
• Savings: calcium chloride increases salt’s effectiveness, therefore reducing the number of applications necessary during storms, saving manpower, equipment and material costs. Plus, it freeze-proofs abrasives to help them embed in ice and snow, so you lose less material to spreader bounce and traffic scattering.

DEICING APPLICATION TIPS

When winter storms hit, correct application of premixed or prewetted materials can make a difference in keeping roads in an easily plowable condition. They save valuable time in treating roads before precipitation begins to bond with the road surface. Application tips from road superintendents who use calcium chloride include:

• Get out early and use adequate amounts of road materials throughout the storm.
• Don’t let ice buildup under snow; keep snow slushy and plow it off.
• Treat hills and intersections first.

CALCIUM CHLORIDE VERSUS COMPETITIVE DEICERS ALONE

Rock Salt (Sodium Chloride)

• Has substantially diminished effectiveness below 25°F (-4°C). The amount of ice melted per pound of rock salt drops 61% from 30°F to 25°F.
• Melts less ice in a given time period
• Has slower melting action.
• Bounces and scatters off road (typically 30%)
• Has environmentally negative impact

Sand and/or Abrasives

• Do not melt ice and snow, just provide some traction
• Bounces and scatters off road
• Requires clean-up

Rock Salt and Sand/Abrasives Combined

• Offer less melting performance over rock salt alone

CALCIUM CHLORIDE GIVES OPTIMUM RESULTS

A road is only as strong and durable as its base … and the stability of the road depends on the proper interlocking of the aggregate. Calcium Chloride:

• penetrates the road aggregate, coating the particles and binding them together. Binding action keeps the road dense and compacted.
• speeds compaction of the base materials.
• maintains moisture in road base to minimize the loss of fines, and maximizes the service level of the wearing course.
• is a cost-effective alternate in recycled asphalt bases.

WETTED SALT WITH LIQUID CALCIUM CHLORIDE

At 25F (-4C), rock salt takes a full 19 minutes to embed in ice and hard-packed snow. But wetted with a 32% calcium chloride solution, rock salt immediately digs in – and holds a close pattern on winter roads as temperatures drop down to 0F (-18C). Wetted salt reduces the need for frequently repeated applications, decreasing material use by as much as 40%.

PREPARING WETTED SALT

Storing 32% calcium chloride solution in bulk tanks allows fast, efficient spraying on rock salt as needed. Except for the equipment and adaptation methods described below, wetted salt application techniques vary only slightly from those for conventional rock salt.

• Spraying in the spreader truck

  Load rock salt into the spreader truck and drive it beneath a spray bar containing calcium chloride solution. You can then easily spray the amount of
  calcium chloride needed onto the salt.

• Spraying during application

  Spreader trucks equipped with calcium chloride tank/feeding systems allow fast and effective application of wetted salt. During application, the salt is
  wetted with the calcium chloride solution and spread simultaneously.

HOW CALCIUM CHLORIDE AND ROCK SALT WORK TOGETHER

ADDITIONAL WINTER USES FOR LIQUID CALCIUM CHLORIDE

• Wetted abrasives:
  spray calcium chloride solution on abrasives to help them embed quickly in ice and snow save applications, plus material, manpower and equipment costs.
• Freeze-resisting stockpiles: spray 32% calcium chloride solution on coal, sand, abrasives, limestone, wood chips, ores and minerals as they are built into stockpiles to keep them free-flowing in winter. Or spray entire stockpiles after they are built for the same long-lasting protection.
• Thawing frozen stockpiles: restore frozen-solid stockpiles to their original condition by adding calcium chloride solution to the frozen masses.

ROAD STABILIZATION PROCEDURES USING CALCIUM CHLORIDE

Stabilizing a road with calcium chloride consists of 7 steps:

1. Scarification of road surface
2. Addition of aggregate
3. Application of calcium chloride
4. Mixing of materials
5. Shaping and cross section
6. Compaction of surface
7. Seal surface with calcium chloride

MARKETS AND USES OF CALCIUM CHLORIDE

• Chemical Manufacture: production of calcium salts
• Construction: cold-weather concrete additive; soil solidification; tractor tire weighting
• Drying Air and Gases: direct drying compound
• Highway Construction: shoulder and base stabilization
• Highway Maintenance: dustlaying; snow and ice control
• Mining: dustproofing and freeze-resisting ore and coal
• Paper Manufacture: increases web strength of corrugating media; improves dye retention
• Petroleum: additive to oil well completion fluids; cementing finished oil wells; drilling mud additive; drying petroleum fractions

Calcium Chloride Manufacturing Process

Step 1. Calcium Chloride & Salt Solution:
Calcium Chloride is formed by the reaction of ammonium chloride and milk of lime

Step 2. Primary Settlers:
Solid impurities are “settled out” and pumped to waste beds

Step 3. Evaporators:
The clarified calcium chloride solution contains sodium chloride, which precipitates at a specific concentration in the evaporators

Step 4. Centrifuge:
Sodium chloride is extracted from the slurry by a centrifuge. Liquid calcium chloride is now available for use

Step 5. Concentrator:
A concentrator removes additional water, producing a 73% calcium chloride solution

Step 6. Drum Flaker:
As the hot, highly concentrated solution of calcium chloride is cooled by a drum flaker, it solidifies into flakes

Step 7. Rotary Dryer:
Rotary dryer leaves only 20% to 23% moisture in the finished product. This yields 77% to 80% flake calcium chloride.

LIQUID CALCIUM CHLORIDE HARD ON ICE, EASY ON CORROSION

The growing need for corrosion-inhibited deicers has prompted manufacturers to explore their production. One example of this is a corrosion-inhibited grade of liquid calcium chloride designed to meet or exceed various states’ deicer standards in all respects. In addition to providing low corrosion versus salt, it has calcium chloride’s operational benefits in that it continues to melt snow and ice at 20°F, the temperature at which salt becomes an inefficient deicer.