This work studies the autogenous self-healing of ultra-high performance concrete (UHPC) incorporating two ultra-fine pozzolanic materials, silica fume (USF) and ultra-fine fly ash (UFFA), under carbonation conditioning. Both ultra-fine pozzolanic materials stimulate the healing of cracks by promoting the secondary hydration of the cement matrix. USF and UFFA form healing products primarily consisting of C-S-H and ettringite, respectively, and the latter product closes the cracks more effectively. Under carbonation conditioning, UFFA accelerates CaCO3 formation with residual uncarbonated ettringites as the structural skeleton, improving the impermeability recovery. USF generates silica gel as a bonding layer between the CaCO3 crystals and the cement matrix after decalcification, which induces more multi-dimensional cracking upon regenerated structures under flexural reloading, thereby enhancing the mechanical property restoration of UHPC. UFFA-modified UHPC is ideal for applications requiring high impermeability, whereas USF-incorporated UHPC is better suited for scenarios with high load-bearing demands.

中文翻译：

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超细火山灰材料对超高性能混凝土在碳化条件下自修复能力的影响


这项工作研究了超高性能混凝土 （UHPC） 在碳酸化条件下结合两种超细火山灰材料 （USF） 和超细粉煤灰 （UFFA） 的自愈。两种超细火山灰材料都通过促进水泥基体的二次水化来刺激裂缝的愈合。USF 和 UFFA 形成主要由 C-S-H 和钙石组成的治疗产品，后者产品更有效地闭合裂缝。在碳化处理下，UFFA 以残留的非碳酸钙矣矿为结构骨架加速 CaCO3 的形成，从而提高了抗渗性恢复。USF 脱钙后生成硅胶作为 CaCO3 晶体与水泥基体之间的粘合层，在弯曲再载荷下对再生结构产生更多的多维开裂，从而增强 UHPC 的力学性能恢复。UFFA 改性 UHPC 非常适合需要高抗渗性的应用，而 USF 结合的 UHPC 更适合具有高承载要求的场景。