Workability and mechanical properties analysis of hybrid fibers reinforced self-compacting concrete incorporating recycled aggregates based on acoustic emission technique

This research focused on maximizing the utilization of recycled aggregates to produce hybrid fibers reinforced self-compacting concrete (SCC) suitable for the majority of construction applications. Hybrid fibers, including milling profiled steel fiber with the volume fraction of 1.0 % and polypropylene fiber with the volume fraction of 0.1%, and mineral admixtures were used to improve the mechanical properties and workability of SCC with recycled aggregates, respectively. The influence of recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) in different replacement ratio combinations (25%-0%, 50%-0%, 75%-0%, 100%-0%, 0%-25%, 0%-50%, 25%-25%) on the workability and mechanical properties of hybrid fibers reinforced recycled aggregates SCC (HFRA-SCC) were studied. The acoustic emission (AE) and digital image correlation (DIC) technique were used to monitor the crack development of HFRA-SCC under compression and splitting tensile loading, respectively. Results showed that both RCA and RFA had negative effects on the workability of HFRA-SCC when their replacement ratio exceeded 25% respectively. The mechanical properties of HFRA-SCC decreased with the in-crease of recycled aggregates replacement ratio as well, while fibers could compensate the strength loss caused by recycled aggregates and significantly increase the toughness of HFRA-SCC. A larger number of AE activities, as well as a sudden spike in cumulative AE energy, could predict the failure of specimen in advance. According to the analysis to the experimental results of this paper, the maximum replacement ratio of recycled aggregates used in HFRA-SCC was proposed.

Automated summary

This research aimed to maximize the utilization of recycled aggregates to produce hybrid fibers reinforced self-compacting concrete suitable for construction applications. The influence of different combinations of recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) replacements on the workability and mechanical properties of hybrid fibers reinforced recycled aggregates self-compacting concrete (HFRA-SCC) were studied. Results showed that the workability and mechanical properties of HFRA-SCC were negatively affected when the replacement ratio of recycled aggregates exceeded 25%. However, the inclusion of fibers compensated for the strength loss caused by recycled aggregates and significantly increased the toughness of the concrete.