Cracking in Concrete Pavements Due to Alkali-Silica-Reactions

In the last few years cracking has been observed in various concrete pavements in some regions of Germany. Besides restraint stresses due to restrained hygric and thermal deformation alkali silica reactions (ASR) can be relevant for this. Regarding ASR in concrete pavements special conditions have to be considered. In opposite to common structures the external supply of alkalis by deicing agents plays an important role on the ASR-development in concrete pavements. The ingress of those alkalis is intensified by microcracking, which is the result of millions of load cycles, affecting the microstructure. The relationship between microcraking, external alkali ingress, ASR and final cracking was studied in extensive investigations in situ and in the laboratory. These studies are of interest for researchers as well as for practitioners.