Improving the Performance of Road Salt on Anti-Icing
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Winter maintenance is a challenging field, especially in parts of the world with a temperate climate. The friction of the road surface has to be kept at an acceptable level so that the demands for traffic safety and mobility are fulfilled. Road salts are used in large quantities for both anti-icing and de-icing objectives, because they depress the freezing point of water.An alternative mechanism of the anti-icing wet pavement freezing has recently been introduced. It says that the salt does not only depress the freezing point, but the presence of them also weakens the ice. If the ice is weakened sufficiently, the traffic load on the road will destroy the ice, giving an acceptable level of friction again. The salts are not so environmentally friendly, and can cause damage to cars and the area surrounding the road. Therefore, alternative chemicals are developed to reduce the amount of salt used on the road. Agricultural By-Products are among these other materials, and are used as an additive to the road salt. This is said to reduce the need for salt, but there is little research that shows how these products work, and whether they work as well as the salts. The objective of this thesis was to test one of these and whether the addition of them would reduce the strength of the ice as much as a salt solution would.The laboratory experiment performed in this thesis has been developed and used earlier by Klein-Paste and Wåhlin (2013). A new parameter was proposed, called equilibrium brine fraction, which could be used to predict whether the ice where sufficiently weakened. Asphalt substrates covered with solutions with different salt and additive concentrations where frozen in an ice laboratory. Afterwards the strength of the ice was tested with a British Pendulum Tester and the percentage of destroyed ice was noted. Many tests were performed at different temperatures, which gave a dataset showing what brine frictions were likely to destroy the ice.The probability that an ice sample failed for a given brine fraction where calculated using binomial logistic regression. Then the results from the experiment performed in this thesis and the ones from the experiment done by Klein-Paste and Wåhlin (2013) were compared.The results showed that the additive of an Agricultural By-Product did neither improve nor have a negative effect on the weakening of the ice.