Engineered geopolymer composites (EGC) are promising alternatives to highly ductile cement-based composites, whereas effectively balancing the strength and ductility of most developed EGC mixes is challenging. This study systematically evaluated the feasibility of incorporating nano-silica (NS) particles to address the problem of balancing strength and ductility in EGC, aiming to develop EGC with extraordinary mechanical properties. The relationship between microstructure and mechanical properties of NS-EGC was studied via X-ray computed tomography (XCT) and backscattered electron microscopy (BSEM) tests, to gain an in-depth understanding of the obtained properties. Results indicate that NS-EGC mixes with superior compressive and tensile behaviour were successfully fabricated based on micromechanics design theory. The optimal NS content and particle size were 1% and 15 nm, where the resulting composite outperformed all proposed EGC in terms of compressive strength (94 MPa), tensile strength (9.17 MPa) and tensile strain capacity (9.06%). The mechanical properties of NS-EGC were strongly dependent on the pore structure, fibre orientation and fibre dispersion, where these microstructural effects can be modified by NS. This study provides a new approach to optimising the strength-ductility balance of EGC through nano-silica incorporation, offering the potential for broadening the application of EGC in high-performance structural materials.

中文翻译：

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纳米二氧化硅对工程地质聚合物复合材料力学性能和微观结构的影响


工程地质聚合物复合材料 （EGC） 是高延展性水泥基复合材料的有前途的替代品，而有效平衡大多数开发的 EGC 混合物的强度和延展性具有挑战性。本研究系统评价了加入纳米二氧化硅 （NS） 颗粒解决 EGC 强度和延展性平衡问题的可行性，旨在开发具有非凡机械性能的 EGC。通过 X 射线计算机断层扫描 （XCT） 和背散射电子显微镜 （BSEM） 测试研究了 NS-EGC 的微观结构与机械性能之间的关系，以深入了解所获得的性能。结果表明，基于微观力学设计理论成功制备了具有优异压缩和拉伸性能的 NS-EGC 混合物。最佳 NS 含量和粒径为 1% 和 15 nm，所得复合材料在抗压强度 （94 MPa）、拉伸强度 （9.17 MPa） 和拉伸应变能力 （9.06%） 方面优于所有提出的 EGC。NS-EGC 的机械性能在很大程度上取决于孔结构、纤维取向和纤维分散，这些微观结构效应可以通过 NS 来改变。本研究提供了一种通过纳米二氧化硅掺入来优化 EGC 强度-延展性平衡的新方法，为拓宽 EGC 在高性能结构材料中的应用提供了潜力。