The load capacity, failure mode and durability of reinforced concrete members are strongly affected by the bond strength between the concrete and the reinforcement. This work presents a physics-based approach to improve the bond strength based on self-stressing effect. Combination of limestone calcined clay cement (LC3) and calcium sulphoaluminate cement (CSA) with different ratios was employed to develop self-stressing function. The addition of CSA induces a remarkable volume expansion of matrix due to the formation of ettringite, it however leads to a decreased compressive strength because of the reduced Portlandite content and increased porosity. A push-out test was conducted to evaluate the interface properties between glass fiber reinforced polymer (GFRP) and LC3-based matrix. The results show that the interface bond strength is highly dependent on the matrix strength under unconfined condition. On the contrary, under confined condition, the interface bond strength increases linearly with the expansion value regardless of matrix strength, attributed to that the self-stressing effect can effectively refine the matrix pores and densify the interface transition zone. The findings from this work demonstrate that the self-stressing effect holds promise to be a plausible method to strengthen the overall properties of reinforced concrete without creating additional carbon emission.

中文翻译：

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自应力和约束对 GFRP-LC3 界面键合的联合影响


钢筋混凝土构件的承载能力、破坏模式和耐久性受混凝土与钢筋之间的粘结强度有很大影响。这项工作提出了一种基于物理的方法来提高基于自应力效应的粘结强度。采用不同配比的石灰石煅烧粘土水泥 （LC3） 和硫铝酸钙水泥 （CSA） 的组合来开发自应力功能。由于钙石的形成，CSA 的添加导致基质的体积显着膨胀，然而，由于硅酸盐含量降低和孔隙率增加，它导致抗压强度降低。进行了推出试验，以评估玻璃纤维增强聚合物 （GFRP） 与 LC3 基体之间的界面性能。结果表明，在无侧限条件下，界面粘结强度与基体强度高度相关。相反，在约束条件下，界面粘结强度随膨胀值线性增加，而与基体强度无关，这归因于自应力效应可以有效地细化基体孔隙并致密化界面过渡区。这项工作的结果表明，自应力效应有望成为一种在不产生额外碳排放的情况下加强钢筋混凝土整体性能的合理方法。