Is there a safe method of melting ice on concrete, meaning one that won’t destroy the concrete? Our walkway is in the shade and getting dangerous. The area is 50 year old concrete so its fully cured, but near our flower beds and new grass – so nothing too toxic would be nice.
Seems there are some conflicting opinions on this and a search through the archives didn’t clear things up.
thanks
BOBS
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Replies
heat
Take a look at http://www.peterschemical.com/Break%20the%20Ice.html
1) various salts and/or acetates, but those attack the reinforcement (undoubtably NOT epoxied coated);
2) alcohol-based antifreezes, like in a car or used on a airplane. But many are toxic and all are expensive.
3) heat - steam, hot water, "radiant" heat through tubing, electric resistence heating, infrared light, etc. Most convenient would be radionuclides of sufficient concentration to maintain 30-40F above ambient. Tough to permit with the NRC, though.
As a retrofit, I'd consider cutting in electric resistence heating wires in the smallest useable path you need to ice melt.
Is there a sealer that will help protect the concrete? The driveway is concrete also, and while after 50 years its still remarkably flat, the end of it where it gets the town's salt is in bad shape. If I could repair that and seal it from whatever the town uses, maybe it would last longer.What do you mean salt and acetates attack the reinforcement? Do you mean the rebar in the concrete?
Yes, salt greatly increases the corrosion rate in steel reinforcement, be it 6"x6" #10 WWF or rebar. That is why those bridges on I-95 in New England fall apart and why they rebuild with epoxy-coated rebar.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Calcium chloride is a bit less corrosive.The MN highway department is experimenting with sugar. I forget exactly what kind -- some sort of sugar that's left over from industrial processing.Basically, anything that dissolves in water will work.
If ignorance is bliss why aren't more people
happy?
I wonder if calcium chloride is less corrosive to concrete. It takes much less of it than rock salt, too. Whatever you use, use little. Most people use way too much. All you need is a small amount. The pellets drill down to the concrete then melt a layer separating the ice from the concrete. After a little while you go in with a spud, lift it all off, then shovel the pieces away. It should not be used to melt the entire thickness of water.
That's how I've been doing it, use a little and then something to break up the ice after a few minutes. Its amazing how fast the melt works, you can hear the ice cracking right away. Still if its at all detrimental to the concrete I'd like to find another method. I'm planning on living here a long time, and I don't want to redo the concrete later.That's why a sealer for the concrete would be ideal.
Edited 12/19/2005 7:49 am ET by BobS
W W Grainger stocks a couple ice melt chemicals that work well. One works down to -8F the other to about -20F. This link should get you there - http://tinyurl.com/bvfbp -. If not go to grainger.com and search for their catalog number 4W973 or 4KA50.
Bob,
Calcium Chloride has the lowest working temperature (-25 degrees) and poses the smallest threat of damage compared to the other conventional solutions (sodium chloride, magnesium chloride, etc).
But the chemical composition isn't the only harmful thing about deicers, it's that people put on way too much, and then just leave it there.
Deicers are meant to be used as a tool to break up the ice, they are not meant to be used on their own. After application, follow up with some hearty chopping and your driveway should be fine. The trouble starts when the deicer is left on teh surface, because adding this chemical to the ice will interrupt the freeze/thaw cycle of the ice. Translation: adding salt to the driveway makes the ice melt, then it refreezes, and melts again. This freeze/thaw cycle will wreak havoc on the cement.
put it on, then get it off.
By the way, pellets are more effective than flakes. Justin Fink - FHB Editorial
So this is essentially why the end of my driveway loooks like crap. The city just spreads deicer or sand but obviously doesn't come back to break up the ice. Fair enough.So having the lowest working temp will reduce the number of freeze/thaws and cause the least havoc. Right?
That's right. The lower the working temperature of the deicer, the lower the outside temperature has to be in order to re-freeze the melted ice.
In other words, if you use deicer with a working temp of 10 degrees, it will melt the ice, but allow it to refreeze if the outside temperature drops below 10.
That's how I understand it anyway, there is some information on this stuff on the web too.
Here's a great listing from madsci.org.......
Three common ice melting ingredients can chemically attack concrete: ammonium sulfate, magnesium chloride and calcium chloride. However, most pavement surface damage results from a natural process called the freeze-thaw cycle, rather than direct chemical attack. The freeze-thaw cycle involves moisture seeping into the cracks and surface pores and freezing. As the moisture changes to ice, it expands which puts stress on surfaces. Ice melting chemicals increase the number of freeze-thaw cycles and can also double the rate of expansion during freezing. Weak pavements may crack or pit under this added stress. Concrete less than one year old, masonry, stone, and asphalt are all particularly vulnerable to freeze-thaw cycles. For these surfaces, the end user may wish to consider using a pure traction aid such as garnet sand, rather than ice melting chemicals. However, if the maintenance of a clear sidewalk or driveway is critical, the end user must weigh the risk of surface damage against the potential liability. Careful selection of ice melting chemical blends and the application of a pavement sealer prior to any snow will help protect the pavement.
Halite (rock salt) is the most common ice melting salt. Halite is mined throughout the world. The primary chemical in rock salt is NaCl, which causes damage to vegetation in concentrated form. Halite is usually medium to dark gray in color if mined from shaft or pit mines. Purer forms of sodium chloride can be solution mined (forcing water into an underground salt dome and evaporating the brine that is forced out to recover the dissolved salt), but these methods are rather expensive for ice melting.
Calcium chloride (CaCl2) and magnesium chloride (MgCl2) can be manufactured or evaporated from naturally occurring brines like the Great Salt Lake in Utah. Both chlorides release heat (exothermic) as they dissolve, which helps it melt ice at very low temperatures. Both chemicals can be hazardous to human health. Both magnesium chloride and calcium chloride can leave a slippery residue that is difficult to clean. Both tend to refreeze quickly and may require frequent reapplication. In addition, both are hygroscopic, which can cause them to clump, harden or even liquefy during storage.
Ammonium Sulphate ([NH4]2SO4) is a fertilizer ingredient that is infrequently used in ice melting salts. It will attack concrete and is not recommended for use on concrete surfaces.
Potassium Chloride (KCl, potash) commonly takes the form of red or white granules. The red grade comes from traditional shaft mines and gets it’s color from iron contamination. The pure white grade is solution mined. Potassium chloride is not as effective at very low temperatures, making pure potassium chloride impractical unless used in conjunction with other ingredients. Potassium chloride is a common plant nutrient. This makes it more safe than halite for landscaping, but it is not always a good idea to add nutrients to the environment even though it may sound good. Excess application of potash can be harmful to the same plants that it would normally nourish at lower concentrations and sometimes increasing plant vigor is worse than harming the plants: In northern Arizona, the Highway Department found that the resulting rich, green grass in freeway medians was causing an increase in accidents between vehicles and wildife seeking out new winter grazing pastures between six lanes of speeding traffic.
Urea is also a common fertilizer nutrient. In its pure form, urea is not corrosive making it a good choice for use around airplanes. Urea must meet strict contamination regulations before being approved to use at airports. However, most of the urea sold for melting ice is considered an agricultural grade is not suitable for use in corrosion sensitive environments.
Ethylene glycol is a liquid deicer. It is commonly mixed with liquid urea and applied using bulk sprayers and tanker trucks applied primarily at airports. It is non-corrosive but poses environmental hazards, especially to grass, animals and to our water supply.
Potassium acetate is a biodegradable liquid deicer. It is also primarily used for airports. Because potassium acetate is corrosive it is often mixed with a corrosion inhibitor.
Calcium magnesium acetate (CMA) was developed as an environmentally responsible alternative to road salt. It is the safest of all ice melting chemicals in regards to vegetation, concrete, water sources, and the applicator. CMA is non-corrosive, biodegradable and can effectively prevent the formation of ice-surface bonds when applied prior to precipitation. Research even suggests that CMA's coating action reduces the risk of moisture penetration and surface damage. CMA is more than 30 times the cost of rock salt. The high cost has limited its practical use. CMA is not effective at very low temperatures. Pure CMA is applied in critical areas where corrosion, vegetation, or water contamination is a primary concern. When blended with other ingredients, CMA can significantly reduce the risk of corrosion and surface damage. In fact, tests have found that a minimum of 20% CMA can reduce corrosion and concrete damage by as much as 80%.
Alpha methyl glucoside (MG-104) is a corn by-product that is most effective when combined with other ingredients. MG-104 provides a catalytic affect that speeds melting, helps other chemicals to work at lower temperatures, and assists in the extension of freeze-thaw cycles to reduce surface damage.
To avoid environmental damage, always use an ice melting blend made from a well selected balance of ingredients. This reduces the risk of excessive concentrations of any single ingredient. Remember, over application of any chemical (including fertilizer), can damage vegetation. The best formulations will not cause environmental harm unless misapplied or used under extreme conditions.
Follow recommended instructions prescribed by the manufacturer, and disperse the melted ice and snow over a wide area to reduce the risk of over concentration. Apply the chemicals as the precipitation begins. This concentrates the chemical at the pavement surface to prevent surface bonding and facilitate ice removal. This will reduce the amount of chemical needed and the potential for damage. Chemicals are also more effective at the pavement surface because the pavement is usually warmer than the snow and ice. Justin Fink - FHB Editorial
Good stuff, Justin. Thanks.
Round here.... Minnesota, 4 out of 5 dentists have said their concrete guys told them to use that liquid form of ice melt. easier on the crete... safe for plants and grass.
SAND! Forget the hi tech chemical nonsense. Sand won't hurt the flowers . Jeffysan
Magnesium chloride
Small white round beads. Will leave a white haze, but should not damage the concrete like salt etc.
Sold at same places as salt, or calcium chloride.