Liquid Chemicals in Snow and Ice Control

04/18/23

District LCC Liquidow Salt Brine

1 0 912.32 1,110,033.00

2 40,729.60 0 363,056.00

3 16,449.37 0 381,580.00

4 94,488.00 0 1,827,784.00

5 480 0 670,902.50

6 835 0 805,213.00

7 210 0 633,374.04

8 16,387.00 8,105.54 120,481.00

9 10,352.00 0 306,885.00

10 3,015.00 0 214,855.00

11 30,665.37 0 61,060.00

12 139,540.16 0 201,842.73

Total 353,152 9,018 6,697,066

04/18/23

Chemicals: How do they work?

Depress the freezing point of water, turning ice or snow into liquid or slush

Solid salts dissolve to form brine solution

04/18/23

Chemical Terms Concentration

% by weight of chemical in solution Eutectic Temperature

Lowest Temp solution will melt ice Endothermic

Requires heat when going into solution Exothermic

Gives off heat when going into solution Hygroscopic

Draws water from the air

04/18/23

Liquid Chemical Uses

Anti-icing FHWA Manual Pre-treatment Plan

Pre-wetting solids Lower temperatures Less bounce and scatter

04/18/23

Anti-icing

Creating a chemical layer ahead of the event to: Prevent freeze bond Prevent frost or black ice formation Increase needed response time

Anti-icing chemicals Liquids Pre-wetted solids

04/18/23

Resource for All Snow & Ice Winter Resource for All Snow & Ice Winter Maintenance Need Maintenance Need

FHWA’s Manual of Practice for an Effective FHWA’s Manual of Practice for an Effective Anti-Icing Program Anti-Icing Program

http://www.fhwa.dot.gov/reports/mopeap/eapcov.htm

04/18/23

OHIO DEPARTMENT OF TRANSPORTATIONSNOW & ICE

PRE-TREATMENT PLAN DRAFTNovember 19, 2003

I. PURPOSE

Pre-treat Priority Routes and any identified trouble spots with liquid material for black ice,unexpected winter events, frost control, and forecasted winter events when conditions warrant.

II. PRE-TREATMENT LIQUIDS

Salt Brine, Magic-O, Caliber, or equivalent

III. APPLICATION

Pre-treat Priority Routes a minimum of twice a week when conditions warrant. On higher volumeroads where material may be tracked away by traffic, pre-treat as close to the onset of an event aspossible.

IV. WHEN CONDITIONS WARRANT

A. Roadways are dry.B. Rain is not forecasted for the next 24 hours.C. Forecasted low temperature to fall within the range

of 20 to 35 degrees Fahrenheit.D. Sufficient time exists for pavement to dry before pavement temperature falls below 20 degrees

Fahrenheit.E. Blowing snow is not anticipated.F. Visual observation indicates sufficient material residue does not exist.

V. IMPLEMENTATION

Regular winter maintenance operations.

VI. SPECIAL CONDITIONS

A. Refer to the Material Application Guidelines.B. “Black Ice” - Pavement temperature is equal to or predicted to be less than the due point

temperature and is equal to or below 32 degrees Fahrenheit. When available, utilize RWIS datafor pavement temperature, dew point temperature, etc..

Pre-treatment Range

OHIO DEPARTMENT OF TRANSPORTATIONSNOW & ICE

PRE-TREATMENT PLAN DRAFTNovember 19, 2003

04/18/23

Anti-icing Rules of Thumb

Less is Best Applied in controlled amounts to leave surface

merely damp Does not result in the flow of liquid across the

pavement Monitor Pavement Temperatures

Quick re-freeze occurs at lower temperatures Monitor Humidity

Higher humidity can cause slickness issues Does not replace de-icing techniques

04/18/23

Pre-wetting Solids

Improves effectiveness at lower temperatures

Reduces bounce and scatter Application at auger (not spinner) is

most effective

Rule of Thumb – It is always more efficient to pre-wet solids

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Typical Liquid Products

Natural Occurring Salts Sodium Chloride – 23% solution Calcium Chloride – 32% solution Magnesium Chloride – 28% solution Potassium Chloride

Other Chemicals Urea Calcium Magnesium Acetate Agricultural Products – Both by-products and

engineered products Various Additives

04/18/23

Phase Diagrams

04/18/23

Evaluating Snow & Ice Control Chemicals

Product Performance Use Criteria Infrastructure Impacts Environmental Impacts Availability Cost

04/18/23

Evaluating Snow & Ice Control Chemicals

Performance (deicing mechanics) Effective temperature range Speed Quantity needed Duration of melting action

04/18/23

Evaluating Snow & Ice Control Chemicals

Use Criteria Equipment requirements Storage & handling needs Application versatility Safety & hygiene considerations

04/18/23

Evaluating Snow & Ice Control Chemicals

Infrastructure Impacts Structures (bridges, buildings) Roadway pavement & structure Vehicles & equipment

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Evaluating Snow & Ice Control Chemicals

Environmental Impacts Soil Animals Vegetation Water Air Human Health

04/18/23

Evaluating Snow & Ice Control Chemicals

Availability Cost

Availability Alternatives Performance Use Criteria Infrastructure Impact Environmental Impact

$$

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Other Natural Salts

Calcium Chloride Natural State - Liquid

Magnesium Chloride Natural State - Liquid

Potassium Chloride Natural State - Solid

Common Use:

Prewetting

Anti-icing

04/18/23

Other Natural Salts

Calcium Chloride Exothermic: gives off

heat Hygroscopic: attracts

moisture Eutectic Temp: -

60oF 30-33% concentration

in solution

Magnesium Chloride Exothermic: gives off

heat Hygroscopic: attracts

moisture Eutectic Temp: -

28oF 22-26% concentration

in solution

04/18/23

CMA(Calcium Magnesium Acetate)

FHWA originally identified CMA as a possible replacement for salt in 1980.

CMA manufactured by reacting dolomitic lime with acetic acid.

04/18/23

CMA Use• Bridge Structures

• Parking Garages

• Environmentally Sensitive Areas

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Corrosion

• More corrosive– Calcium Chloride– Sodium Chloride– Magnesium Chloride– CMA– Urea

• Less Corrosive

04/18/23

Chemicals

Specifications Material Safety Data Sheet (MSDS) Sample and test (certification) Talk to other users: effectiveness,

concerns, problems Storage Issues – some chemicals

require circulation

04/18/23

Material Handling

Safe Chemical Handling Labels MSDS (Material Safety Data Sheet) Personal Protective Equipment

“Common Sense”

& the “Right Attitude!”

04/18/23

MSDS Material Safety Data Sheets

Manufacturer’s Data Product ID Major Components Hazardous Ingredients Physical Data Fire & Explosion Data Reactivity Data Health Hazard Info Emergency & First Aid Procedures Personal Protection Equipment Spill, Leak & Disposal Procedures

04/18/23

Chemical Handling

Toxicity vs. Hazard Hazard = toxicity + exposure Toxicity: LD50 & LC50

““Just how toxic are snow Just how toxic are snow and ice control chemicals and ice control chemicals

to human health?”to human health?”

04/18/23

Toxicity ClassificationCategory Oral LD50 (Rat,

mg/KG body wt)

Probable Human Lethal Dose

Extremely Toxic <1 Taste

Highly Toxic 1-5 Teaspoon

Moderately Toxic 50-500 Ounce

Slightly Toxic 500-5,000 Pint

Practically Nontoxic 5,000-15,000 Quart

Relatively Harmless >15,000 >1 Quart

04/18/23

Toxicity Comparison *LD50

(rat, mg/KG body wt.) highest toxicity first

Material

Nicotine

Caffeine

Calcium Chloride

Aspirin

Salt (Sodium Chloride)

Calcium Magnesium Acetate

Magnesium Chloride

Vitamin C

*LD50

<1

192

1000

1000

3000

3150

8100

11900

Human Category

Extremely Toxic

Moderately Toxic

Slightly Toxic

Slightly Toxic

Slightly Toxic

Slightly Toxic

Practically Nontoxic

Practically Nontoxic

04/18/23

Snow & Ice ChemicalsCommon Potential Problems

Eye Irritant Skin Irritant Breathing Irritant - Dust or Mist

Inhalation

“Good Personal Hygiene & Personal Protective Equipment”

04/18/23

Chemical Handling

Gloves Shoes & Boots Eye Protection Dust Mask Attitude

04/18/23

Choosing a New Chemical

A big opportunity (as you shift to liquids)

What do you need the chemical to do?

What constraints do you have on how the chemical will perform?

Approach is based on the “Guide for Selecting Anti-Icing Chemicals” Copy included on reference disk

04/18/23

Purpose of the guide

Differentiate between different chemicals on the basis of performance acknowledge that different agencies

have different needs allow factors to be weighted

04/18/23

Categories Used

Freezing point depression

Consistency Viscosity Specific gravity

Environmental Impact Heavy metals BOD/COD Toxicity

Stability Corrosion Handling Documentation

Unspecified content

Completeness

04/18/23

Most Important Ones

Depends on your needs Is corrosion a big issue for you? What about the environment?

Definitely freezing point depression Consistency Complete documentation

04/18/23

Why Freezing Point Depression?

Tells whether it’s suitable for your climate

Tells when you should stop using it because it’s too cold

Tells how much you’ll need to fight a typical storm

04/18/23

How Freezing Point Depression?

Based on the eutectic curve BUT, not just the eutectic point

It’s more an indicator of melting action Need to know two temperatures

At half the concentration of the EP At quarter of that concentration

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04/18/23

How does NaCl do?

The half point is about 15 F Typically represents lower end of the

useful range of salt use The quarter point is 26 F

Illustrates impact of dilution

04/18/23

Chemical Comparison

NaCl (salt) sodium chloride -21 -6 23

CaCl calcium chloride -51 -60 30

MgCl magnesium chloride -33 -28 22

KCl potassium chloride -11 +13 20

KAc potassium acetate -60 -76 49

CMA calcium magnesium acetate -27 -17 32

Urea -12 +10 33

Chemical Eutectic Temp Conc.

oC oF % by weight

04/18/23

Chemical ComparisonEutectic vs Effective Temp

NaCl (salt) sodium chloride -21 -6 -9 +15

CaCl calcium chloride -51 -60 -32 -25

MgCl magnesium chloride -33 -28 -15 +5

KCl potassium chloride -11 +13 -4 +25

KAc potassium acetate -60 -76 -26 -15

CMA calcium magnesium acetate -27 -17 -6 +21

Urea -12 +10 -4 +25

Chemical Eutectic Effective*

oC oF oC oF

04/18/23

What about Consistency?

The addition of organic chemicals and by-products makes some new liquid products much more variable than traditional chemicals

You MUST know that the product you use this week performs the same as what you used last week

04/18/23

How do we Measure Consistency?

Have to use index tests Viscosity and specific gravity are

easy to do and will quickly tell you if something isn’t right

The only long term answer is good quality program with suppliers

04/18/23

Why Documentation?

You can’t compare products if you don’t have enough information

Any worthwhile product will come with documentation, test results and so forth

Provide a critical input for your choice

04/18/23

How Documentation?

Two factors How much of the product is termed

“other” in the chemical analysis? Do the suppliers give you all the

info you need?

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Another factor for Consistency and Documentation

Legal issues You HAVE to know what you’ve put

on the road If you don’t, you are very vulnerable

during the deposition/trial process

04/18/23

So how do we rate different products?

Set levels within each category Weight the categories according to

which matter to you Then grade the chemicals (multiply

their category level by their weight to get a grade point score)

See the guide for more details

04/18/23

Pacific Northwest Snowfighters

http://www.wsdot.wa.gov/partners/pns/

Evaluate and establish specifications for materials used in winter maintenance

Approved product list

04/18/23

Salt Institute

Salt Institute http://www.saltinstitute.org/

Salt Institutes “Winter Maintenance Material: What are you Using?”

Salt Institute’s “Are You Using the Right Amount of Ice Control Chemical?” (based upon findings of NCHRP 6-13)

Copies included on reference disk

04/18/23

SICOP Website

Snow and Ice Pooled Fund Cooperative Program, SICOP http://www.sicop.net

Snow and Ice List Serve http://www.sicop.net/snow_and_ice_list-serve.htm

04/18/23

Reference Materials

FHWA “Manual of Practice for an Effective Anti-Icing Program” Appendices A and B

http://www.fhwa.dot.gov/reports/mopeap/eapcov.htm

Nixon’s “Guide for Selecting Anti-icing Chemicals” (on reference disk)

NCHRP 6-13 “Guidelines for Snow and Ice Control Materials and Methods” Chapter 6 Hard copy provided

Chemical Recommendation Tool Worksheet On reference disk

04/18/23

Reference Materials (continued)

NCHRP 526 “Snow and Ice Control: Guidelines for Materials and methods” Table A-6 Equivalent rates (on reference disk)

NCHRP Synthesis 344 “Winter Highway Operations” Table 4, Chemicals used by various agencies (on reference disk)

04/18/23

Material Details

Specifications (on reference disk) Liquid Calcium Chloride (32%) Corrosion Inhibited Liquid Calcium Chloride Rock Salt Contract

Product Literature SBA-2 and Caliber by Syntech Corp. De-Ice 55 and De-Ice S by Road Solutions Magnesium Chloride products by SWI Ice B’Gone by Sears Ecological

04/18/23

04/18/23

Website Development

• http://www.dot.state.oh.us/maintadmin/odot_snow_and_ice_program.htm