型钢-地聚物再生骨料混凝土黏结性能试验研究

Experimental study on bonding performance of steel-geopolymer recycled aggregate concrete

  • 摘要: 为研究型钢-地聚物再生混凝土(Steel Reinforced Geopolymer Recycled Concrete,SRGRC)界面黏结性能,以型钢保护层厚度、锚固长度、箍筋间距、矿渣取代率及龄期为变化参数,共完成了16个试件的静力推出试验。分析了试件的破坏模式、荷载-滑移曲线、黏结强度及失效机制。其中各试件破坏过程与裂缝发展规律基本一致,裂缝主要沿型钢翼缘分布;荷载-滑移曲线整体呈三阶段特征:初始无滑移段、上升段及最终下降段。适当提高矿渣取代率及型钢保护层厚度可显著增强界面黏结强度。试件龄期的延长使材料内部聚合反应加深,当龄期由90D增至180D时对黏结韧性提升幅度最明显,增幅达46.9%。龄期延长和配箍率提升均能够延缓试件损伤的发展。基于试验数据,建立了SRGRC界面黏结强度的计算公式与相应的黏结-滑移本构模型,计算结果与试验结果吻合良好。结果表明矿渣取代率、保护层厚度、龄期及配箍率是影响其黏结性能的关键参数;所提出的黏结强度计算公式和黏结-滑移本构模型能够准确预测SRGRC的界面行为,为该类组合结构的工程应用提供了理论依据。

     

    Abstract: To investigate the interfacial bonding properties of Steel Reinforcement Geopolymer Recycled Concrete (SRGRC), sixteen static push-out specimens were designed, varying in steel protective layer thickness, steel anchorage length, stirrup spacing, slag replacement rate, and curing age. Analysis of the test data encompassed failure modes, load-slip curves, bond strength, and failure mechanisms. Consistent failure processes and crack development were observed, primarily concentrated around the steel flange. Load-slip curves exhibited a consistent pattern: a no-slip region, an ascending region, and a descending region. Significant influences of slag content and steel protective layer thickness on bond strength were identified. Increased curing age enhanced the material's polymerization, leading to a notable 46.9% increase in bond toughness between 90 and 180 days. Extended curing age and increased stirrup ratio effectively delayed damage initiation and propagation. Finally, based on the experimental results, a calculation formula for SRGRC interfacial bond strength and a corresponding bond-slip constitutive model were developed, demonstrating good agreement with the experimental data. The results indicate that the slag replacement ratio, concrete cover thickness, age, and stirrup ratio are key parameters affecting the bond performance of SRGRC. Furthermore, the proposed calculation formula for bond strength and the bond–slip constitutive model can accurately predict the interfacial behavior of SRGRC, thereby providing a theoretical basis for the engineering application of this type of composite structure.

     

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