Ice Melt Products:
Two most popular:
Sodium Chloride (NaCl, a.k.a. Rock Salt) - Cheapest - Not effective below 25°F
- Can leach into soil
- corrosive to paved surfaces

Calcium Chloride (CaC12)
- Good at temperatures to -25°F
- Less harmful to vegetation.
- About three times more expensive than rock salt, but you only need to use 1/3 as much it.

Source: Comparing Five Common Chemicals for deicing at thriftyfun.com

Safe Step® Ice melts for safer sidewalks and driveways - North American Salt Company
Safe Step is available (but not all mixtures) at Ace and Home Depot.

product
Most Common
3300 ROCK SALT	NaCl	20 to 5°F
7300 EXTREME	CALCIUM CHLORIDE	-25°F
Other 2	50/50 rock salt and Potassium chloride	12°F
Others
4300 DUAL BLEND®	sodium chloride and magnesium chloride	-7°F
5300 MAX BLEND	magnesium chloride and calcium chloride	-10°F
6300 ENVIRO-BLEND®	MG 104®1 magnesium chloride and potassium chloride	-10°F
8300® EXTREME	MAGNESIUM CHLORIDE hexahydrate	-15°F

1. MG 104® - A patent-pending formulation that combines magnesium chloride and potassium chloride into a product that is gentler for people, pets, and lawns. The patented formula contains our powerful melting catalyst, MG 104®, which helps prevent refreezing up to 2½ times longer than conventional products.

2. A 50/50 rock salt potassium chloride is listed as one of the most effective mixtures recommended in several places. See UNH
See Others and more information on specific products below.

Road Salt | The Cary Institute of Ecosystem Studies

Product	Cost Relative to Road Salt	Freezing Point Depression (degrees C per unit weight)	Effective Lower Limit (degrees F)	Corrosive?	Aquatic Toxicity	Other Environmental Impacts
Road Salt or Rock Salt (NaCl)	$1.00	1	20	Yes	Moderate	Roadside tree damage
Potassium Chloride (KCl)	$1.60	0.78	12	Yes	Very	K fertilization
Magnesium Chloride (MgCl2)	$2.40	0.29	5	Yes	Very	Mg addition to soil
Calcium Chloride (CaCl2)	$5.70	0.53	-25	Very	Moderate	Ca addition to soil
CMA- Calcium Magnesium Acetate (C8H12CaMgO8)	$19.30	0.30	0	No	Indirect	Decreased aquatic oxygen
Potassium Acetate (CH3CO2K)	$26.30	0.60	-15	No	Indirect	Decreased aquatic oxygen
Urea (CH4N2O)	$1.80	0.97	15	No	Indirect	N fertilization
Sand	$0.60	0	-	No	indirect	Sedimentation

Tips:
Research shows that the shape of deicing particles affects the speed of their penetration through the ice. Uniformly shaped spherical pellets of 1/16" to 3/16" penetrate ice faster and more efficiently than other shapes. Irregularly shaped particles tend to melt randomly in all directions. Flakes melt as much horizontally as they do vertically.

Wet snow followed by freezing rain:
A comment by TheMisanthrope at A Midwesterner's Snow Shoveling DOs and DON'Ts says,
"If you're going to shovel, salt the sidewalk. If you're not going to salt, don't shovel. It's easier to walk on snow than a sheet of bare ice."

A comment by gromm says, "Any sidewalk with any traffic that doesn't get shovelled quickly turns into the most treacherous surface you can imagine: a bumpy sheet of ice interspersed with icy holes."

My opinion is that driving or walking on snow will eventually pack it into ice. If you only need to use it for a couple of times

Calcium Chloride (CaC12)

Pros: This chemical gives off heat so it works well at low temperatures ( -25° F ). Because it doesn't contain as many chemical additives as regular rock salt does, it is usually considered less harmful to vegetation. It is available in flakes, pellets or liquid form.
Cons: CaC12 attracts moisture from the air so it can leave behind a slippery residue that can be harmful to carpet, tile, shoes and your pet's feet. It can also be corrosive to metal.
Cost: About three times more expensive than rock salt, but you only need to use 1/3 as much it.

Sodium Chloride (NaCl, a.k.a. Rock Salt)
Pros: This is an effective deicer for areas that receive vehicle traffic because of the additional heat friction created by moving tires and heat exhaust.
Cons: It draws heat from the environment rather than releasing it, so it is not very effective below 25° F . Salts can leach into soil, changing its chemical composition and eventually flowing into local waterways. Salt is also highly corrosive to paved surfaces, buildings and metal.
Cost: Rock salt is generally the least expensive deicing product.

Calcium Magnesium Acetate (CMA)
Pros: Made from dolomitic limestone and acetic acid, CMA is salt-free and biodegradable. It will not harm the environment if used sparingly and is less corrosive to concrete and less damaging to plants.
Cons: It only works to 25° F . It can sometimes dilute and refreeze, leaving a slick residue on walkways.
Cost: About twenty times more than regular rock salt.

Potassium Chloride (KCL)
Pros: -
Cons: Increased potential to burn foliage and inhibit rooting of plants due to its high salt content. Performs poorly below 20° F .
Cost: Costs three t° F ive times as much as sodium chloride, but doesn't work as well at low temperatures, so you need up to ten times as much to be effective.

Urea (NH2CO NH2)
Pros: Primarily used as a fertilizer, Urea has a lower potential to damage vegetation compared to potassium chloride.
Cons: Performs poorly below 20° F. It still has the potential to burn your lawn, shrubs and other plants when the chemicals dissolve ice and collect in one area. Very little of most fertilizer-based deicers are actually beneficial to your lawn. Most of the nutrients end up running off frozen soil in the spring and flowing into storm drains, where they cause massive algae blooms in local waterways.
Cost: Varies, but generally inexpensive. Other De-Icing Products

Potassium Acetate (KC2H3O2)
Pros: Works to -75° F . Potassium Acetate is considered safer than salt for steel and other metal structures. It is biodegradable and non-corrosive.
Cons: It attracts moisture from the air so it may keep pavement wet, leaving a slick residue. It also lowers oxygen levels in waterways if allowed to enter storm drains and is not always readily available to the public.
Cost: Eight times more than rock salt.

Magnesium Chloride
Pros: Effective to -13° F .
Cons: Is corrosive and attracts moisture from the air, which can keep pavement wet.
Cost: Two times more costly than rock salt, and you also need twice as much of the product for effective results.

Ethylene Glycol & Propylene Glycol
Pros: Propylene Glycol is considered a safer alternative for mammals than Ethylene Glycol. It is often found in "pet friendly" deicers.
Cons: Both products are considered by the EPA to be highly toxic to aquatic organisms.
Cost: Three t° F our times the cost of rock salt.

Many products that claim to be "eco-friendly" are often just a combination of the most common five chemicals used in deicers, but blended in such a way as to minimize environmental risks and keep costs low for consumers.

For Wet, Heavy Snow: Apply deicer product as soon as snow beings falling in order to prevent it from bonding.
For Sleet & Freezing Rain: Apply deicer product early on during these conditions to prevent ice from building up.

Liquid Snow Shovel is applied before it snows to keep snow and ice from adhering to surfaces for 7 days. See Properties

Abrasives are sometimes mixed with deicers like calcium chloride for a long lasting effect. Mix at a rate of one part deicer to three parts abrasive.

product	price	amt.	$/lb	lbs/100sf	$/100sf
sand	$3.74	60 lbs	$0.07
EcoTraction	$29	10 lbs	$2.90
Chicken Grit	$10	50 lbs	$0.20

See:
Salt vs. Sand to Prevent Slips on Ice - Bob Vila
CHERRY STONE® TRACTION GRIT
See Salt Alternative at Old English Sheep Dog (oes.org)
EcoTraction - award-winning winter safety alternative to road salt/chlorides.

Links:
See Comparing Five Common Chemicals for deicing at thriftyfun.com for more.
See also:
Ice Melting Products - Salt for Melting Ice - Deicers - Calcium Chloride - Ice Melter | MeltSnow.com
Best Rock Salt & Ice Melt Reviews - Consumer Reports

Road Salt | The Cary Institute of Ecosystem Studies
Ice melts for safer sidewalks and driveways - North American Salt Company
Winter Ice Melters | U. New Hampshire
Ice Melt Options | bedfordfields.com/blog/