Effect of different fibers on impermeability of steam cured recycled concrete

Recycled concrete solves the problems of building resource waste and environmental pollution. The addition of fiber can improve recycled concrete's bearing capacity and durability. In order to study the influence of different fibers on the impermeability of recycled concrete, macro and micro experiments were carried out on 60 compressive samples and 30 impermeability samples with a different fiber content of 0%, 0.5%, 1.0%, and 1.5% in this paper. The effects of steel fiber, polypropylene fiber, and glass fiber on the impermeability of recycled concrete were explored. The compressive strength, impermeability height, and economic cost of the sample were evaluated through multi-criteria optimization, and the optical fiber type and content were obtained. The results show that the addition of fiber can improve the overall compactness of the internal structure of recycled concrete, inhibit the expansion and extension of micro-cracks in the sample, and improve the compressive strength and impermeability of recycled concrete. Among them, the compressive strength and impermeability can be increased by 15.36% and 34.41%. However, when the content of the three fibers exceeds 1.5%, the increased range shows a downward trend, indicating that 1.0% steel fiber and 1.0% glass fiber have the best improvement effect on the compressive strength and impermeability of recycled concrete. Finally, the multi-criteria optimization results show that the selection of 1.0% polypropylene fiber and glass fiber is the best fiber type and content to improve the compressive strength and impermeability of the sample.