Fresh and Hardened Properties of Sustainable RSF-Reinforced Recycled Aggregate SCC

Abstract

Developing low-carbon and green self-compacting concrete (SCC) is essential for advancing sustainable building materials. In this study, recycled steel fibers (RSFs) and industrial by-products were combined for the production of SCC made with recycled aggregates (RSCC), with the aim of introducing multiple waste materials to improve the sustainability of SCC. 14 RSF-reinforced RSCC mixtures (RSF-RSCC) were prepared by replacing natural coarse aggregates (NCAs) with recycled coarse aggregates (RCAs) and cement with supplementary cementitious materials (SCMs) and reinforced with RSFs. The parameters studied in this paper include replacement levels of RCAs (75%), SCMs (50% and 75%), and RSFs (0.5%, 1.0%, and 1.5%). The influence of different content of RSFs and SCMs combinations on workability and mechanical properties was studied, and the synergistic influence of RSFs and SCMs was investigated in detail. The microstructure characteristic was investigated using a scanning electron microscope. The test results show that the addition of SCMs can compensate for the adverse effects of RSFs on the fresh properties, and all RSF-RSCC exhibited superior workability. Furthermore, the incorporation of RSFs enhanced the mechanical properties of RSCC, resulting in remarkable improvement in the compressive and flexural strengths. The combined incorporation of RSFs and SCMs led to an excellent synergistic effect, which resulted in significant enhancements in the mechanical properties.