A number of researchers have conducted experiments on particle penetration and ice disbondment characteristics of various deicers. Variables include deicer unit weight, particle size, atmospheric conditions, substrate temperature, etc.
Reaction times range from a few minutes to several tens of minutes. Data from experiments indicate the initial ice-melting reaction begins almost immediately upon application, depending on the deicer’s eutectic and the temperature of the ice, pavement, and air. Undercutting at the ice-pavement interface takes longer because the particles must penetrate the snow-ice mass to reach the pavement interface. Lower temperatures flatten the curve. For example, Nixon, et al. compared deicer penetration and ice undercutting capabilities of NaCl wetted with CaCl2 and untreated NaCl. The authors showed that NaCl penetrated ice immediately and undercut the ice in 5-6 minutes at a temperature of 10 ºF (–12.2 ºC). Their work indicates that NaCl wetted with CaCl2 accelerates penetration reaction time for the first few minutes after contact. The curves become parallel within approximately ten minutes.
McElroy, et al. (1988) compared ice undercutting rates and deicer application rates for seven deicers and mixtures of deicers. Variables include temperature, time, and application rate. The authors presented laboratory data showing that CaCl2 begins undercutting a 1/8 in layer of ice in 7-8 min at 15 ºF. Similarly, NaCl begins undercutting in 17-18 min; and KCl and urea begin undercutting in >60 min. Dickinson (1959) compared amounts of ice melted by mixtures of calcium and sodium chloride at different temperatures and time intervals. He showed that CaCl2 melted 2.5 lb ice/lb of deicer and NaCl melted 1.6 lb ice/lb in 15 min at 20 ºF. Dickinson’s Table 2 includes data for temperatures from 0 ºF to 26 ºF and time intervals of 15 min-6 hr. These data indicate that ice melting begins almost immediately. Sinke et al. (1976) Compared ice undercutting rates for NaCl and CaCl2 at various temperatures. They showed reaction times for NaCl of approximately 5-8 min at 15-25 ºF and reaction times for CaCl2 of 2-5 min under the same conditions.
Kaufmann (1960), referring to B. C. Tiney (1934), showed comparative melting capacities of calcium and sodium chlorides at various t temperatures. NaCl melted quantities of ice varying from 3.2 lb at -6.5 ºF (eutectic) to 46.3 lb at 30 ºF. 77%-80% CaCl2 melted 3.7 lb of ice at -6.5 ºF and 31.1 lb of ice at 30 ºF. Kaufmann also reported on penetration time in minutes of grains of NaCl in ice, based on grain size and temperature. A 1/8” salt grain penetrated >1” in 20 min at 25 ºF and 1” in approximately 50 min at 8 ºF. Larger particles penetrated to a greater depth. A ¼” particle penetrated 2” in 50 minutes at 25 ºF and 2” in 120 min at 8 ºF.
References
Dickinson, William E. 1959. Ice-Melting Properties and Storage Characteristics of Chemical Mixtures for Winter Maintenance. Highway Research Board Bulletin 220. 38th Annual Meeting January 5-9.
Kaufmann, Dale W. 1960. Sodium Chloride, The Production and Properties of Salt and Brine. Reinhold Publishing Corporation. Chapter 23, pp 562-565
Kersten, M.S., L.P. Peterson, and A.J. Toddie, Jr. 1959. A Laboratory Study of Ice Removal by Various Chloride Salt Mixtures. Highway Research Board Bulletin 220. 38th Annual Meeting January 5-9.
McElroy, A.D., Robert R. Blackburn, and Henry Kirchner. 1990. Comparative Study of Chemical Deicers – Undercutting and Disbondment. Transportation Research Board Annual Meeting. January.
McElroy, A.D., Robert R. Blackburn, Jules Hagymassy, and Henry Kirchner. 1988. Comparative Study of Chemical Deicers. Transportation Research Record 1157.
Nixon, J.G., D.R. Larrimore, and E.H. Mossner. 1979. A Laboratory Comparison of Prewet and Untreated Rock Salt as Ice Removal Agents. Dow Chemical Company.
Sinke, G.C. and E.H. Mossner. 1976. Laboratory Comparison of Calcium Chloride and Rock Salt as Ice Removal Agents. Transportation Research Record 598. Maintenance Management, The Federal Role…
Tiney, B.C. 1934. Highway Research Board, Proc. 13:333
Trost, Susan E., Frank J. Heng, and E.L. Cussler. 1987. Chemistry of Deicing Roads: Breaking the Bond Between Ice and Road. Jour. Transp. Engrg. Vol. 113, No. 1. January 1.
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