Carbonation resistance and microstructural analysis of Low and High Volume Fly Ash Self Compacting Concrete containing Recycled Concrete Aggregates

The present study investigates the carbonation resistance of Low Volume Fly Ash (LVFA) and High Volume Fly Ash (HVFA) based Self Compacting Concrete (SCC) made with Coarse Recycled Concrete Aggregates (RCA). In order to study the carbonation resistance of LVFA and HVFA based SCC mixes made with RCA, accelerated carbonation tests were conducted for an exposure period of 4, 12 and 16 weeks. The results indicate that with the increase in RCA content as replacement of Coarse Natural Aggregates (NA), decrease in the carbonation resistance of SCC mixes has been observed. The inclusion of metakaolin (MK) as a mineral admixture has been found to compensate the loss in the carbonation resistance on account of substitution of NA with RCA to some extent. The current investigation also emphasises on the microstructural study performed by Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA) for validation of observed results.