Tsardaka Eirini-Chrysanthi, Tsampali Evangelia, Stefanidou Maria
Laboratory of Building Materials, School of Civil Engineering, Aristotle University of Thessaloniki, 54006 Thessaloniki, Greece.
Materials (Basel). 2024 Aug 20;17(16):4120. doi: 10.3390/ma17164120.
In the last decades, nano-silica (NS), nano-alumina (NA), and nano-calcium oxide (NC) particles have been incorporated into cementitious materials, and it seems that each one of them contributes uniquely to the materials' properties. This research explores the influence of each nanomaterial on the fresh properties of cement pastes and their compressive strength evolution over one year. Low proportions (1.5% by weight) of nanomaterials were added to cement pastes, and their fresh properties, such as heat of hydration and X-ray diffraction patterns in the first hours, were analyzed. The compressive strength and open porosity were also measured long-term. The acceleration of hydration heat in NA-cement pastes is linked to enhanced hydration product formation at early ages. Among the tested nanomaterials, NA increased compressive strength by 10% at later ages. Although the fresh properties of NC-cement pastes remained unaffected, their open porosity decreased by 54% at 28 days. In contrast, the increase in heat of hydration in NS-cement pastes did not result in significant strength improvement. Based on these findings, NA was selected for ultra-high-performance cement (UHPC)-based material use. Its incorporation not only preserved the ultra-high-performance (UHP) properties but also provided additional benefits such as an increase in compressive strength under a CO atmosphere. Through detailed analysis, this research establishes that nano-alumina incorporation optimizes the microstructural development and compressive strength of ultra-high-performance cement-based systems, presenting a novel advancement in enhancing the mechanical properties and durability of these materials under various environmental conditions.
在过去几十年中，纳米二氧化硅（NS）、纳米氧化铝（NA）和纳米氧化钙（NC）颗粒已被掺入胶凝材料中，而且它们似乎各自对材料性能有独特贡献。本研究探讨了每种纳米材料对水泥浆体新拌性能的影响以及它们在一年时间内的抗压强度发展情况。将低比例（重量比1.5%）的纳米材料添加到水泥浆体中，并分析其新拌性能，如最初几小时的水化热和X射线衍射图谱。还长期测量了抗压强度和开口孔隙率。NA水泥浆体中水化热的加速与早期水化产物形成的增强有关。在测试的纳米材料中，NA在后期使抗压强度提高了10%。尽管NC水泥浆体的新拌性能未受影响，但其开口孔隙率在28天时降低了54%。相比之下，NS水泥浆体中水化热的增加并未导致强度显著提高。基于这些发现，NA被选用于超高性能水泥（UHPC）基材料。其掺入不仅保留了超高性能（UHP）特性，还带来了额外的好处，如在CO气氛下抗压强度增加。通过详细分析，本研究确定掺入纳米氧化铝可优化超高性能水泥基体系的微观结构发展和抗压强度，为在各种环境条件下提高这些材料的力学性能和耐久性带来了新进展。
