Matrix strength and interfacial bonding between aggregate and matrix are critical factors influencing the performance of lightweight cementitious composites (LCC). This study proposes an environmentally friendly and efficient strategy for developing high-performance fly ash cenospheres (FAC)-containing LCC by combining sodium sulfate (SS) and calcium-silicate-hydrate (C-S-H) seeds. Moreover, the roles of SS and C-S-H seeds on achieving superior strength of LCC were elaborated by characterizing the hydration, microstructure, pore structure, and interfacial zone. Results show that the combined use of C-S-H seeds and SS accelerated silicate and aluminate hydration, shortened the setting time of LCC, and refined the pore size. FAC particles provided a nucleation site for the precipitation of ettringite due to the increased aluminum concentration and formation of gypsum on interface. Furthermore, C-S-H seeds and SS significantly improved the interfacial zone between FAC and matrix due to the enhanced pozzolanic reactivity of FAC. C-S-H seeds and SS primarily functioned through a physical nucleation and chemical activation to improve the matrix strength and interfacial zone, respectively, resulting in a high-performance LCC. Consequently, remarkable increases of 131.4 ± 19.8 % and 29.0 ± 5.1 % in early and late compressive strength of LCC were achieved. These findings present a novel approach for developing high-strength lightweight concrete with enhanced early strength under ambient curing.

中文翻译：

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了解 C-S-H 种子和硫酸盐在含粉煤灰 cenosphere 的轻质胶凝复合材料中的作用

基体强度以及骨料与基体之间的界面结合是影响轻质水泥基复合材料 （LCC） 性能的关键因素。本研究提出了一种通过结合硫酸钠 （SS） 和钙硅酸盐水合物 （CSH） 种子来开发高性能含飞灰云圈 （FAC） 的 LCC 的环保高效策略。此外，通过表征水合、微观结构、孔隙结构和界面区，阐述了 SS 和 C-S-H 种子对实现 LCC 优异强度的作用。结果表明，C-S-H 种子和 SS 联合使用加速了硅酸盐和铝酸盐的水化，缩短了 LCC 的凝结时间，细化了孔径。由于铝浓度增加和界面上石膏的形成，FAC 颗粒为钙矾石的沉淀提供了成核位点。此外，由于 FAC 的火山灰反应性增强，CSH 种子和 SS 显着改善了 FAC 和基质之间的界面区。CSH 种子和 SS 主要通过物理成核和化学活化发挥作用，分别提高基质强度和界面区，从而产生高性能 LCC。因此，LCC 的早期和晚期抗压强度分别分别提高了 131.4 ± 19.8 % 和 29.0 ± 5.1 %。这些发现为开发在常温养护下具有增强早期强度的高强度轻质混凝土提供了一种新方法。