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Salt Asphalt

Ice resistant asphalt with salt/ice disperser built in
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Salt melts ice by interfering with the crystal strucure as it begins to form. If you added a similar substance to road surface material (probably not salt 'cos it wold wash away) you would have ice free roads that never need gritting.
JB36, Apr 17 2002


       I bet it wouldn't work. Surely the 'substance' would have to react with, or dissolve in the ice, thereby depleting itself.
stupop, Apr 17 2002

       The great trans-continental Salt Lick highway.  Interesting idea though.  A much less practical approach would be to create a porous surfaced pavement with a saline (or other de-icing) solution forced up through it when icing conditions are present.  A 'sweating' road surface, if you will.  Of course, the result could be something very slippery, now that I think about it.
bristolz, Apr 17 2002

       The salt doesn't react with the ice, it just interferes with it's structure. Unfortunately it needs to dissolve to do this. Perhaps another substance who's molecules could be anchored to the road but still do their job on the surface could be found. Substances work like this to do other jobs, i think a car's catalytic convertor contains one.
JB36, Apr 17 2002

       my first thought was all the wildlife out on the road licking the salt. a roadkill nightmare.
rbl, Apr 17 2002

       I thought salt lowered the freezing point of water, but there you go. someone will put us right.
po, Apr 17 2002

       it does, but it does it by getting in the way of the bonds which form between water molecules. once it gets so cold the effect is lost so the result is, it lowers the freezing point of water.
JB36, Apr 17 2002

       my point is that you need to add the substance whatever it is; salt, mustard, pepper, custard powder,even ground up weeny crumbs of road surface stuff, to the ice for it to melt - not incorporate into the surface of the road.
po, Apr 17 2002

       Until you can come up with another substance that does this job without depleting itself (which, it seems to me, is a necessary part of the process), this idea is a WIBNI and ought to be m-f-d. But I'll give you some time to think about it.
waugsqueke, Apr 17 2002

       It doesn't seem WIBNI to me. The idea could be crudely carried out if the salt blocks that the road is paved with are frequently replenished. What is interesting to me is the notion that a road surface be made of some substance that chemically interacts with water and causes the freezing point to be lowered dramatically or vanquishes the ice altogether. Maybe ethylene glycol? (Now that'd be a nasty enviro mess). I've read somewhere that deicing can be successful with a propylene-glycol and xantham mix; both are food grade substances.
bristolz, Apr 18 2002

       Roads tend to be environmental nightmares as it is (not that they should be made any worse).
bristolz, Apr 18 2002

       someone alert our resident chemistry expert (surely we have a dozen lying around here somewhere?). this could be excellent if it were possible.   

       My basic requirements for pavement additive: dirt-cheap and available in vast quantities, nontoxic to critters like frogs; undamageable by heat (during manufacture, summer), wear, and sunlight; extremely nonslippery in dry, wet, and frozen conditions.
white, Mar 18 2003


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