Service life prediction and environmental impact evaluation of recycled aggregate concrete with supplementary cementitious materials

Abstract

The application of recycled aggregate concrete (RAC) can promote the harmonious development of resources and environment. However, the mechanical properties and chloride permeability resistance of RAC are worse than those of natural aggregate concrete (NAC), which limits RAC application in chloride-attack environment. In order to solve this problem, supplementary cementitious material (SCM) is added into RAC to improve its performance. In this research, the changes in durability-based service life of RAC due to the addition of unconventional SCMs composed of red mud (RM), ground granulated blast furnace slag (GGBFS) and/or glass power (GP) have been studied. Based on prepared reinforced concrete specimens with 4 kinds of recycled coarse aggregate (RA) substitution level and 5 kinds of binder composition, the accelerated corrosion tests were conducted for determining corrosion rate. Using the corrosion rate data detected in this paper, combined with the chloride rapid migration coefficient and chloride threshold etc. data, the service lives of reinforced concrete structures with SCMs concrete were found to be much longer than those with Ordinary Portland cement (OPC) concrete. Furthermore, life cycle assessment integrated with strength and service life was performed for concrete with specific mix design to study the effect of unconventional SCMs addition on the environmental behaviors of RAC with different RA content. The results showed that RA substitution level had little effect on material environmental benefits, but the improvement effect of SCMs was obvious. Finally, the multi-criteria analysis method was used to evaluate the overall performance of concrete with different binder composition and RA content in terms of strength, service life and environmental impact. For any substitution level of RA, the SCMs composition with optimal effect in improving overall performance of concrete was 10% RM and 15% GGBFS (percentage by weight of binder).