Side effects of calcium chloride

Calcium chloride (CaCl2) is mainly used as a summer dust suppressant, but its share in winter maintenance has increased in recent years and is nowadays about 13% of the total use of de-icing chemicals. In some areas its share may be even 40%. The purpose of this report was to study comprehensively possible side-effects of calcium chloride in winter maintenance. Side-effects of calcium chloride were compared to the ones of sodium chloride (NaCl).. This report covered the following side-effects: vehicle corrosion, bridge corrosion, and corrosion of equipment, effects on asphalt pavements, tyres and brakes as well as effects on natural resources such as vegetation, terrestrial and aquatic biota and animals, soil structure, surface and groundwater. In addition effects on animal paws and footwear were investigated briefly . Results of this study showed that generally calcium chloride increases the corrosion of vehicles and bridges more than sodium chloride. Additionally it weakens the performance of bentonite sealing layers, reduces the friction coefficient between road surface and tyres and between brake disc and brake pads in specific conditions and forms a thin layer in the metal panels and windscreen of vehicles. However, the effects on natural resources are more diverse. Calcium ions ameliorate the quality of soil and strengthen the cell walls of plants, but calcium chloride releases more chloride ions per mole than sodium chloride and is more harmful to vegetation and groundwater. However the final quantity of released chloride ions per mass depends on the dosage of the road salt. All the above mentioned side-effects are very much dependent on environmental factors such as temperature, relatively humidity and salt concentration. Therefore many factors must be taken into account in the evaluation of overall effects of calcium chloride. In Finland de-icing chemicals are mainly used in temperatures above -7 degrees. In temperatures like these, there is no big difference in the deicing effectiveness and performance of calcium and sodium chlorides. However based on this report, calcium chloride seems to be more harmful than sodium chloride for the built environment, but the effects on nature are equal or slightly smaller.This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf/3201014-vkalsiumkloridin_sivuvaik.pdf