Optimization of four different mineral additive combinations to reduce alkali silica reaction.

Presence of alkali silica in aggregates that are used in concrete production causes formation of cracks and decrease of performance over time in concrete.The first damage caused by ASR in Turkey had been observed in certain highway bridges in Izmir locality in 1995. It was found that some aggregates in other regions of Turkey also have a character to cause ASR.The purpose of the study was to minimize potential alkali silica reaction expansion in concrete and mortars produced with the aggregates that are used in constructions in our region.Accelerated mortar bar test method was employed in the study. It was observed in experimental study that that the use of 20-25% fly ash, 25-35% blast furnace slag and 10% silica fume and metakaolin as mineral additive reduced ASR.According to optimization studies, it is appropriate to use 5-10% silica fume, 5% metakaolin, 10-15% blast furnace slag and 10-20% fly ash as mineral additive in optimum mixtures giving ideal expansion value.It was found that the use of 65% of cement together with 35% silica fume, metakaolin, blast furnace slag and fly ash in mineral additive combinations prevents ASR. [ABSTRACT FROM AUTHOR]