Effect of fly ash and limestone powder on inhibiting alkali aggregate reaction of concrete

Abstract

Abstract The alkali aggregate reaction (AAR) about the aggregate marked with W1# was studied by using of four kinds of methods, including accelerated mortar bar test (AMBT), mortar bar length test (MBLT), concrete prism method (CPM) and rock column method (RCM). AMBT showed that the expansion ratio of the specimens at 14 days was 0.200%, and the expansion ratio at 28 days was 0.404%; MBLT showed that the expansion ratio at 3 months was higher than 0.050%, and the expansion ratio at 6 months was higher than 0.100%; CPM showed that the expansion ratio at 39 weeks was higher than 0.040%. These studies above indicated that W1# aggregate was the aggregate with potential alkali-silica activity. RCM tests showed that the aggregate doesn’t have potential alkali-carbonate activity. The inhibiting experiments showed that the expansion ratio at 14 days and 28 days were less than 0.10% by adding more than 45% (Wt/%) limestone powder or adding 15% (Wt/%) fly ash, meanwhile, the expansion ratio at 14 days and 28 days were all less than 0.10% after adding 15% (Wt/%) limestone powder and 30% (Wt/%) fly ash or adding 25% (Wt/%) limestone powder and 25% (Wt/%) fly ash, respectively. Mesh structures were formed by the hydration products in the micro structure, and no micro cracks and the white flocculent products could be observed inside and outside of the samples. All the results above confirm that AAR of the aggregate was inhibited effectively, and it will play the useful role in AAR research.