硅灰与纳米TiO₂复掺对高掺量再生骨料混凝土性能的协同优化研究

Research on the Synergistic Optimization of the Performance of High-Content Recycled Aggregate Concrete by the Compounding of Silica Fume and Nano-Tio₂

摘要: 本文针对再生骨料100%掺量混凝土性能劣化难题，系统开展硅灰与纳米TiO₂复掺改性研究。通过设计6组对比实验，综合运用力学性能测试、压汞分析、微观结构表征等手段，揭示复掺体系对混凝土性能的影响规律与作用机制。结果表明，10%硅灰与1.0%纳米TiO₂复掺时，混凝土28天抗压强度达52.3 MPa，相较基准组提升41%；劈裂抗拉强度提升56%至3.82 MPa，峰值后位移延性增加50%；孔隙率降低30.6%至12.7%，有害孔占比减少23%；氯离子扩散系数下降50.4%，300次冻融循环后动弹性模量保留率达89%。研究证实，硅灰与纳米TiO₂通过“物理填充–化学激活”协同作用，构建“致密填充–界面强化”循环，为高掺量再生骨料混凝土工程应用提供关键技术支撑。

Abstract: This paper systematically conducts research on the compounding modification of silica fume and Nano-Tio₂ to address the problem of performance deterioration in concrete with 100% recycled aggregate content. By designing six sets of comparative experiments and comprehensively applying mechanical property testing, mercury intrusion analysis, microstructure characterization and other means, the influence law and mechanism of the admixture system on the performance of concrete were revealed. The results show that when 10% silica fume is compounded with 1.0% Nano-Tio₂, the 28-day compressive strength of the concrete reaches 52.3 MPa, which is 41% higher than that of the benchmark group. The splitting tensile strength was increased by 56% to 3.82 MPa, and the post-peak displacement ductility was enhanced by 50%. The porosity decreased by 30.6% to 12.7%, and the proportion of harmful pores decreased by 23%. The diffusion coefficient of chloride ions decreased by 50.4%, and the retention rate of dynamic elastic modulus after 300 freeze-thaw cycles reached 89%. Research has confirmed that silica fume and Nano-Tio₂ work in synergy through “physical filling-chemical activation” to form a “dense filling-interface strengthening” cycle, providing key technical support for the engineering application of high-content recycled aggregate concrete.