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In practical engineering, it is difficult to separate the mixture of waste bricks and waste concrete, and the performance of recycled concrete is poor due to the inherent defects of recycled aggregates. This study enhances the mechanical properties of mixed recycled aggregate concrete by incorporating waste fibres, and systematically evaluates the effects of fibre content, fibre length , and recycled brick aggregate replacement ratio on the mechanical properties and uniaxial compressive stress strain characteristics of recycled concrete. The results show that the incorporation of waste fibres can significantly improve the mechanical properties of recycled concrete, with the best improvement effect observed for fibres with a length of 19 mm. When the fibre content is 0.10 %, the cubic compressive strength , peak uniaxial compressive stress and elastic modulus increase the most, while when the fibre content is 0.08 %, the splitting tensile strength and flexural strength increase the most. On the basis of the axial compression stress strain curve, the stress strain constitutive model of waste fibre-reinforced mixed recycled aggregate concrete is established. The microstructure characterization reveals the improvement mechanism of the internal structure of the recycled concrete by the waste fibres. After adding waste fibres to mixed recycled aggregate concrete, the dual-effect indicators of “CO 2 emission-strength” and “material cost-strength” decrease by 17.03 % and 12.52 %, respectively, achieving the effective unity of mechanical performance improvement and sustainable development goals. This study provides experimental basis and theoretical support for the application of waste fibre-reinforced mixed recycled aggregate concrete. • The influence of waste fiber on the mechanical properties of recycled concrete. • The axial compression constitutive model of waste fiber recycled concrete. • The microscopic mechanism of synergistic enhancement of fiber is revealed. • Realize the collaborative optimization of intensity-carbon emission-cost.
Zhang et al. (Tue,) studied this question.