Norwegian Experience with Use of Magnesium Chloride.

The main goal with the magnesium chloride project has been to verify how the amount of salt is affected by alternative salting methods and also study which possibilities magnesium chloride gives to operate under temperatures where sodium chloride does not work. In addition it has been an aim for the project to investigate the duration of an action and the time to dryup the road surface after salting with different chemicals. One of the purposes has therefore been to study how different methods affect friction and friction development under varying winter road conditions. One of the hypotheses has been that magnesium chloride due to the fact that this is a hygroscopic salt, under certain conditions can result in slippery road conditions. The development in friction can be an indicator on the effects that can be expected on the road conditions by use of different salting methods. Besides studying the deicing effect and consequences on the friction,it has also been given focus to the environmental issue. From an environmental point of view it is important to reduce the amount of salt. A longertime before the road surface dry up can result in less dust and lastly magnesium chloride can reduce the negative impact on organisms and vegetation along environmentally exposed surroundings like parks in cities. The test area comprises 42 km road network in the inner city of Oslo. The main method used on this road network is prewetted sodium chloride with a 20 % solution of magnesium chloride added. The proportion is 70 % dry salt and 30% brine in percentage of weight. On a reference road in the same area brine based on sodium chloride is used instead of the magnesium chloride solution. The project has been going on for 4 winter seasons now, and will be finally reported in 2005 after the 2004/2005 season. The results after three winter seasons shows some interesting tendencies towards less salt consumption with the method based on prewetting with magnesium chloride and positive effects on the friction improvement. For the covering abstract see ITRD E143097.