Validation of carbonation behavior of self compacting concrete made with recycled aggregates using microstructural and crystallization investigations

The sustainable binary and ternary blends of Self compacting concrete (SCC) were prepared with replacement of natural fine aggregates (NFA) and natural coarse aggregates (NCA) with recycled fine aggregates (RFA) and recycled coarse aggregates (RCA) respectively sourced from construction and demolition (C&D). Accelerated carbonation tests were conducted using conventional acid/base method. The results indicate that with the increase in RFA and RCA content as replacement of NFA and NCA, decrease in the carbonation resistance of SCC has been observed. The addition of Metakaolin (MK) has been found in recompensing the respective loss in carbonation resistance up to some extent. For validating the results, microstructural and crystallization studies have been performed with the help of Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. In addition to above, compressive strength tests were also conducted for reference.