Relevant Interactions for Alkali-Silica-Reactions in Concrete Pavements

In the last few years cracking in concrete pavements often is attributed to alkali-silica-reaction (ASR). Although this is a very important aspect other impacts such as traffic loads and restraint stresses due to thermal and hygral effects may not be neglected. In many cases interactions between various causes can become relevant and a superposition of different mechanisms will be responsible for the final cracking. In opposite to common structures the external supply of alkalis by deicing agents plays an important role in 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 microcracking, external alkali ingress, ASR and final cracking was studied in extensive investigations in situ and in the laboratory.