De-icing salts

More detailed statistical analyses (chemical element balance, principal component analysis and factor analysis) demonstrate that soil contributes >50% to street dust, iron materials, concrete/cement and tire wear contribute 5-7% each, with smaller contributions from salt spray, de-icing salt and motor vehicle emissions (5,93-100). A list is given in Table VII of the main sources of the elements which contribute to street dust. 

Figure 1. Germination of selected cvs. of amaranth as affected by various concentrations of de-icing salt.

Rowe, L. C. Chance, R. L. in "Automotive Corrosion by De-icing Salts", Babolan, R., Ed. National Association of Corrosion Engineers Houston, 1981, p. 133. 

The resistance to attack by aggressive liquids which would commonly be chlorides from marine environments or de-icing salts and sulfates from ground water. 

Table 3.18 Air entrainment improves the freeze-thaw resistance of concrete in the presence of de-icing salts...

Air-entraining admixtures, therefore, produce concrete which is more durable to conditions of freezing and thawing, particularly in the presence of de-icing salts, more resistance to sulphate attack, provides better protection to embedded reinforcement and is more tolerant of poor curing conditions. There appears to be no... 

In spite of the decades of use of air-entraining agents (AEA) for the improvement of frost resistance of concrete, there has been a significant increase in reported cases of poor performance of concrete exposed to freezing and thawing, particularly where de-icing salts are used. Examination of specimens from a large number of concrete structures showed that only about half of the structures had an air-void system (AVS) that met the... 

Similarly, different results have been found for the impact of brake wear particles. While unequivocally a strong enrichment of brake-related chemical trace elements (Sb, Ba, Cu) is found at trafficked sites [63], the quantification of overall PM contribution from brake wear is associated with uncertainties. An even wider range of emission factors was found for re-suspension of road dust (cf. Table 4). It should be noted that re-suspension may be a strong source of PM during wintertime when de-icing salt is spread out. For a traffic site in southern Germany exceedance of the daily PM limit value could be tracked back to road salting in 12 of 43 cases [66]. 

Norrstrom and Jacks (1998) Concentration and fractionation of heavy metals in roadside soils receiving de-icing salts. Sci. Total Environ., 218, 161-174. 

Corrosion of reinforcement is probably the most widespread cause of deterioration in concrete. The expansion produced by rust formation causes the surrounding concrete to crack and spall. In a sound concrete, rusting is prevented by the high pH of the pore solution, which stabilizes an oxide film on the steel that inhibits further attack. This film is unstable at lower pH values, which can result from carbonation or leaching, or in the presence of Cl . Sources of the latter include sea water or salt spray, de-icing salts used on roads, certain aggregates, especially those available in desert climates, and CaClj used as an accelerator. Though now widely prohibited, this can... 

Another source of urban salinization is the use of road de-icing salts. Salt has been used for road de-icing for several decades, particularly in the eastern and northeastern states in the United States and Canada. The use of road salt improves fuel efficiency and reduces accidents at the same time, it causes salinization of associated groundwater. In 1990, more than 10.5 Mt of salt were used for road de-icing (Richter et al., 1993). Brine generated in storage piles of salt (Wilmoth, 1972) and from the dissolution of salts that are applied directly to the roads (Howard and Beck, 1993 Williams et al., 1999) can contaminate water resources. If salt is applied as a powder, its particles may become airborne and transported for considerable distances downwind (Jones and Hutchon, 1983 Richter et al., 1993). 

Antiskid systems (road resurfacing epoxies) Skid resistance Resistance to water, de-icing salts, fuels, dilute acids and alkalis For deslicking a smooth roadway... 

Coatings, for protection of concrete and metals protection of concrete from de-icing salts and other chemicals ability to control water absorption adhesion... 

Loop and lighting sealants excellent adhesion to concrete, asphalt and steel in dry or damp conditions without primer resistance to de-icing salts and hydrocarbons Seahng horizontal cable slots in concrete and asphalt pavement Bedding and sealing aronnd airport lighting units... 

De-icing salts Compounds that prevent the formation of ice (e.g. calciiun chloride, sodium chloride). 

In other cases, the initial problem may be more subtle. Plants growing near streets and walkways are often damaged in winter by the de-icing salts that are washed into the soil, although symptoms may not appear until spring. 

Corrosion of reinforcing steel in concrete (elevated highway. Providence, RI), where road de-icing salts combine with acid precipitation to produce a severe environment. (Photo by Robert Baboian.)... 

The section on metallic corrosion clearly indicates that the conventional method of classification of environments into marine, industrial, and rural no longer is adequate. More specific information is needed about the actual chemical components in the atmosphere as well as humidity and other factors. Specific environments also are addressed in the metallic corrosion section. For example, the automotive environment in the northeastern United States is particularly severe because of the combination of acid deposition and the use of road de-icing salts. These factors exert a synergistic effect on the corrosion behavior of auto-body steel and on exterior anodized aluminum automobile trim. 

Auto body corrosion adjacent to stainless steel trim occurs in environments where de-icing salts are used. The effects of acid deposition combined with road salts produces a synergystic effect on the degradation of automobiles. (Photo by Robert... 

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