Carbonation resistance of sustainable self-compacting concrete with recycled concrete aggregate and fly ash, slag, and silica fume

Abstract

This study focused on the problem of recycling construction and demolition wastes as well as industrial waste by-products into sustainable concrete materials. By combining addition of three different industrial waste by-products, an environmentally friendly recycled aggregate self-compacting concrete (RA-SCC) mix was put forward. Carbonation resistance and microstructure of SCC incorporating high volumes of industry by-products and recycled aggregates were studied in this paper. A total of 9 RA-SCC with 50%, 75% supplementary cementitious materials (SCMs) and different SCM combinations were prepared, which consist of binary mix with fly ash (FA), ternary mix with FA and ground granulated blast-furnace slag (GGBS), and quaternary mix with FA, GGBS, and silica fume (SF). An exposure period of 3, 7, 14, and 28 days was adopted for accelerated carbonation tests. The test results indicate that, as RCAs content increased, RA-SCC carbonation depth increased. The carbonation depth of SCC with 100% RCAs increased by 49.35% compared to that of normal SCC. In addition, carbonation resistance of RA-SCC mixes with a given compressive strength decreased with increasing SCM content. However, the loss in carbonation resistance was greatly mitigated by the combined addition of different SCMs, on account of the substitution of cement with industrial by-products and natural aggregates with RCAs. The combined addition of different SCMs enhanced the carbonation resistance of RA-SCC mixes. The test results were validated through microstructural analysis using scanning electron microscopy (SEM), and X-ray diffraction (XRD). A comparison between predictions calculated using existing models and measured carbonation depth was implemented. By taking into account the effect of RCAs and SCMs, a modified carbonation model in conjunction with fib carbonation model was put forward.

Keywords:

• Recycled aggregate self-compacting concrete (RA-SCC)
• supplementary cementitious materials (SCMs)
• recycled coarse aggregates (RCAs)
• carbonation
• microstructural analysis

Acknowledgments

The authors wish to gratefully acknowledge the support of these organizations for this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data, models, and code generated or used during the study appear in the submitted article.

Additional information

Funding

This research was funded by Open Project of Key Laboratory of Engineering Structure Performance Evolution and Control, Tongji University (Grant No. 2019KF-2), Open Project Fund of Ministry of Education Key Laboratory of Concrete and Prestressed Concrete Structures, Southeast University (Grant No. CPCSME2017-04), National Natural Science Foundation of China (Grant No. 52178144), and Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX22_1327).