Effect of Prewetting Brines and Mixing on Ice-Melting Rate of Salt at Cold Temperatures: New Tracer Dilution Method

Abstract

A novel test method has been developed to measure the ice-melting rate of deicers. The ice-melting rates of prewetted salt were determined by measuring the change in the concentration of chloride (Cl−) or magnesium or calcium cations (Mg2+ or Ca2+, respectively) in the ice melt as tracers. The method is substantially more precise than the SHRP H205.1 standard and has the further advantage of measuring ice-melting and salt dissolution rates simultaneously. Brines were preequilibrated with ice at −19.3°C (−2.7°F) and blended with solid salt to determine the effect of different prewetting brines on the ice-melting rate of the solid salt component only. The measured equilibrium ice-melting capacity of sodium chloride (NaCl) agreed well with the theoretical value calculated from the NaCl freezing point curve. Under a condition of no mixing, solid salt yielded 0.87% of its total available ice-melting capacity after 60 min when wetted with NaCl brine and 9.7% when wetted with calcium chloride (CaCl2) brine. Mixing raised the yield of ice melt to 27.1% and 50.5% after 60 min when wet with NaCl and CaCl2 brines, respectively. The CaCl2 brine was slightly more effective than the magnesium chloride (MgCl2) brine at enhancing the ice-melting rate of salt. The test method promises to be a useful tool for permitting a more precise optimization of prewetting brine composition, concentration, and brine-to-salt ratio at different temperatures. The method may also permit better determination of the cost-effectiveness of different prewetting strategies and provide deeper insights into the mechanism of chemical ice melting.

Time Dependent Release of Salts From Asphalt Pavement Containing Anti-Icer Additives

“…However, at a given temperature the ice melting capacity of CaCl 2 is very close to that of NaCl on an anhydrous chemical basis (at temperatures where NaCl can melt ice at all, i.e., above the NaCl-water eutectic temperature of −6°F). The ice melting capacity of a chemical can be calculated from its freezing point curve in water ( 14 ). This is illustrated in Figure 4, which shows a comparison of the ice melting capacities of NaCl, CaCl 2 , and MgCl 2 calculated from their respective freezing point curves over a range of temperatures ( 15 , 16 ).…”

The Effect of Additives on the Low Temperature Ice-Melting Capacity of NaCl

“…However, since the amount of pre-wetting is small compared to the amount of solids, it will probably not drastically lower the ice melting capacity. Further, since there is research showing that it might impact other important measures, such as the melting rate (Koefod, 2017), it may be beneficial to pre-wet the deicer to increase longevity in cold temperatures.…”

Effect of Temperature and Prewetting for Ice Penetration with Sodium Formate

“…The focus on those properties leaves a demand for reliable and consistent methods for measuring deicer penetration and, to some extent, undercutting (7). In addition, most of the experiments were performed with deicers commonly used for road deicing, namely sodium chloride (NaCl), magnesium chloride (MgCl 2 ) and calcium chloride (CaCl 2 ) (12, 13). No documented research data has been found for the melting performance of formates (NaCOOH and KCOOH) using improved methods.…”