Research on carbonation resistance of Recycled Concrete using coarse and fine recycled aggregates

摘要

The effects of the uses of coarse and fine recycled aggregates as replacements of coarse and fine natural aggregates on carbonation resistance of recycled aggregate concrete (RAC) were determined. In this study, three series of concrete mixtures were prepared with water to binder (w/b) ratios of 0.36, 0.33, and 0.30. The coarse recycled aggregate was used as 0%, 30%, 60% and 90% replacements of coarse natural aggregate and fine recycled aggregate as 0%, 10%, 20%, and 30% replacements of fine natural aggregate. Furthermore, fly ash and slag were used by 15%, 25%, 35% and 45% as replacements of cement. Although the uses of coarse and fine recycled aggregates had a negative effect on the carbonation resistance of RAC, it was found that the addition of fly ash and slag was able to mitigate this detrimental effect. The carbonation depth would increase with an increasing loading level and reduce when increasing the sand ratio.