减缩材料、纤维类型和修复厚度对纤维增强自密实混凝土修复梁抗弯行为的影响

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2024-11-26 DOI:10.1016/j.cemconcomp.2024.105868

Jingjie Wei, Kamal H. Khayat

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引用次数: 0

摘要

自密实混凝土（SCC）已成为修复混凝土结构的一种高效方法，但有关不同纤维和减缩材料（减缩外加剂，SRA；超吸收聚合物，SAP；膨胀剂，EA）的组合对修复结构抗弯行为影响的研究却很少。本研究旨在探讨三种不同的减缩材料（1.25%-2.5% SRA、4%-8% EA 和 0.2%-0.4% SAP）、四种纤维类型（两种大合成纤维 MSFA 和 MSFB；5D 钩状钢纤维 5D；80% 3D 钩状钢纤维 + 20% 短钢纤维 STST 组合）对纤维增强自密实混凝土（FR-SCC）的新拌和硬化性能、水泥水化和干燥收缩的影响。具体而言，研究了不同的减缩材料、纤维类型和两种修复厚度（分别相当于棱柱构件总高度的 1/3 和 2/3）对使用 FR-SCC 修复的复合试件抗弯性能的影响。此外，还研究了现有混凝土与 FR-SCC 之间的粘结强度，以揭示复合梁的抗弯行为。结果表明，与使用含 4%-8% EA 和 0.2%-0.4%SAP 的 FR-SCC 修补的棱柱试样相比，使用含 1.25% SRA 的 FR-SCC 修补的棱柱试样表现出优异的抗弯性能。掺入 4%-8% EA 和 0.2%-0.4% SAP 会对修复试样的抗弯性能产生不利影响，这是因为现有混凝土-FR-SCC 的界面强度和纤维-基质粘结强度较低。与不使用任何减缩材料的 FR-SCC 相比，在 FR-SCC 中使用 SRA、EA 或 SAP 可将与基材的粘结强度提高 10%-60%。使用 1.25% SRA 的粘结强度最高，与使用 SAP 和 EA 的粘结强度相比，分别提高了 10%-37%和 33%-44%。随着试样修复厚度的增加，加入 SRA、EA 或 SAP 对提高修复试样的弯曲韧性和残余强度有不同的效果。此外，在 SCC 中掺入 5D 纤维和 1.25% SRA 表现出优异的抗弯性能，其次是 MSFA、STST 和 MSFB 纤维。将修复厚度从复合梁总高度的 1/3 增加到 2/3，可使弯曲韧度和残余强度分别提高 133% 和 160%，这与纤维类型和试样横截面上纤维体积的增加有关。

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Effect of shrinkage-mitigating materials, fiber type, and repair thickness on flexural behavior of beams repaired with fiber-reinforced self-consolidating concrete

While self-consolidating concrete (SCC) has emerged as a highly effective approach for the repair of concrete structures, there have been few investigations regarding the effect of the combination of different fiber and shrinkage-mitigating material types (shrinkage-reducing admixture, SRA; superabsorbent polymer, SAP; and expansive agent, EA) on the flexural behavior of repaired structures. This study aims to explore the influence of three different shrinkage-mitigating materials (1.25%–2.5 % SRA, 4%–8% EA, and 0.2%–0.4 % SAP), four fiber types (two macro synthetic fibers, MSF_A and MSF_B; 5D hooked steel fibers, 5D; a combination of 80 % 3D hooked steel +20 % short steel fibers STST) on fresh and hardened properties, cement hydration, and drying shrinkage of fiber-reinforced self-consolidating concrete (FR-SCC). Specifically, the effect of different shrinkage-mitigating materials, fiber types, and two repair thicknesses corresponding to 1/3 and 2/3 of the total height of prismatic element on the flexural performance of composite specimens repaired using FR-SCC was studied. The bond strength between existing concrete and FR-SCC was also investigated to reveal the flexural behavior of the composite beams. The results indicate that prismatic specimens repaired with FR-SCC made with 1.25 % SRA showed excellent flexural performance compared to those repaired using FR-SCC made with 4%–8% EA and 0.2%-0.4%SAP. The adverse effect of the incorporation of 4%–8% EA and 0.2%–0.4 % SAP on flexural behavior of repair specimens can be attributed to a lower existing concrete-FR-SCC interfacial and fiber-matrix bond strengths. Using SRA, EA, or SAP in FR-SCC improved bond strength with substrate by 10%–60 % compared to FR-SCC without any shrinkage-mitigating materials. The use of 1.25 % SRA showed the highest bond strength, which increased by 10%–37 % and 33%–44 %, respectively, compared to that made with SAP and EA. As the increase in the repair thickness of specimens, the incorporation of SRA, EA, or SAP had different efficiencies to enhance the flexural toughness and residual strength of the repair specimens. Furthermore, the incorporation of 5D fiber and 1.25 % SRA in SCC showed excellent flexural performance, followed by MSF_A, STST, and MSF_B fibers. The increase in the repair thickness from 1/3 to 2/3 of the total height of the composite beam enhanced the flexural toughness and residual strength by a maximum of 133 % and 160 %, respectively, attributing to fiber type and the increase in fiber volume at the cross-section of specimens.

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.