Deicing is fighting ice that already bonded. Anti-icing is stopping the bond before it forms, and it's the cheapest ice control there is. Guidance from Connecticut's Green Snow Pro program says anti-icing can be more than 50% more efficient than deicing.1
Salt brine, by the numbers
- 23.3% sodium chloride is the target concentration. That's the eutectic mix, with a freeze point near −6°F.2
- Roughly 2.5 lb of salt per gallon of water makes 23.3% brine. Check it with a salinity meter (salimeter): 23.3% reads about 1.176 specific gravity, or about 85% on a salimeter.1
- A gallon of 23.3% brine carries about 2.3 lb of salt.3 At 20 gallons per lane-mile, that's about 45 lb of salt per lane-mile, compared with 300 lb or more for a typical granular pass.2
Liquid rates
| Use | Rate | Source |
|---|---|---|
| Roadway anti-icing, salt brine | 20 gal/lane-mile baseline; DOTs typically run 40–75 gal/lane-mile | MnDOT2; WTI / Clear Roads research4 |
| Lots: before frost or black ice, or on a schedule | 0.3–0.6 gal / 1,000 sq ft (brine); 0.2–0.4 (CaCl₂ or MgCl₂) | MPCA / MN LTAP5 |
| Lots: before light or moderate snow | 0.3–0.8 gal / 1,000 sq ft (brine); 0.2–0.4 (CaCl₂ or MgCl₂) | MPCA / MN LTAP5 |
| Contractor pre-treatment benchmark | 30 gal/acre (about 44 gal/lane-mile, or 0.7 gal / 1,000 sq ft) | SIMA3 |
To convert lane-mile rates to per-1,000 sq ft, divide by 63.36.5 Too high a rate can make pavement slick or tracky.5
When to spray, and when not to
- Up to about three days ahead of a storm, as long as rain won't wash it off. It dries to a white residue and waits.1
- Before frost and black-ice nights, especially bridges, ramps, shaded drives and entrances.
- Not before an event that starts as rain. The rain washes it away before the freeze.1
- Careful with blowing snow: wet pavement can make dry blowing snow stick. Brine is the better choice there because it dries.2
Pre-wetting granular salt
Salt has to become brine before it melts anything. Pre-wetting gives it that head start and keeps it on the pavement. The most common rate is about 10 gallons per ton, with a typical range of 8–12 gal/ton.6 Above about 30 gal/ton you're making a slurry, which works even faster.6 The APWA puts typical pre-wetting at about 8–10 gal/ton.7 If you pre-wet, cut your granular rate. New Hampshire best practices cite 15–20% reductions as typical.8
Can't pre-wet on your trucks? Pre-treated (treated) salt brings the liquid with it, and it's usually dyed so you can see it, often blue or red.6
Next in the guideBounce, scatter and refreeze →