Alkali-silica reaction in municipal road construction

摘要

With reference to the General Circular on Road Construction No. 04/2013 on alkali reactivity, many traffic areas in the municipal sector are assigned to moisture class WS on account of being allocated to load classes Bk1.8 to Bk100. The suitability of aggregates or concrete mixes for moisture class WS can be verified by subjecting the concrete to WS aggregate testing or an ASR performance test. A lack of appropriate verification in many regions means that ready-mixed concrete can often not be supplied. The WS classification was selected for motorways (high dynamic loads and external alkali supply). On account of the lower speeds involved, the dynamic traffic load is however not as high in municipal areas. An additional aspect is that de-icing agents are often not used in urban areas, so that there is less likelihood of alkali supply and a lower risk of deleterious ASR here than in the case of motorways. Moisture class WA or a comparable classification may therefore be sufficient. Drill cores from the municipal road construction sector and laboratory concretes were therefore tested with the methods developed for moisture classes WS and WA in a research project. The test results were taken as a basis for drawing up criteria for alkali reactivity assessment and for the practical assignment of concrete moisture classes in the municipal road construction sector.