Dauerhafte Betonfahrbahndecken durch Verwendung unterschiedlicher Bindemittel in Ober- und Unterbeton.

Durable concrete pavements using different binders in top and bottom lift It is a matter of common knowledge that ground granulated blast furnace slag and siliceous fly ash can be used to mitigate alkali-silica-reaction (ASR) in concrete. Nonetheless such materials are seldom used for the construction of concrete pavements in Germany, as their application can impair the deicer-scaling resistance of the concrete. In two-lift concrete pavements a possible approach to avoid this problem is to use cements with a higher proportion of blast furnace slag only in the thick bottom lift, thus minimizing its susceptibility to ASR. The thin top lift, which is subjected to a high level of mechanical and freeze-thaw stress, is still produced with Ordinary Portland Cement, hence ensuring a sufficient deicer-scaling resistance. However, this approach is currently hindered by the German technical standards for concrete pavements, which require the use of the same cement in the top and bottom lift. Furthermore the standards do not permit the application of siliceous fly ash to partly substitute cement in concrete pavements. It was therefore the aim of a research project to obtain the necessary knowledge for assessing potential benefits and risks of a more flexible use of binders in concrete pavements. [ABSTRACT FROM AUTHOR]