Superhydrophobic cementitious composites are potential candidates to effectively mitigate long-term performance deterioration of concrete buildings due to external water infiltration. However, traditional superhydrophobic modification leads to a significant reduction in compressive strength. To address this, a carbon sequestered superhydrophobic mortar with a water contact angle of 153°–162° and an approximate 10 MPa increase in 28-day compressive strength was developed via synergistic effects of micro- and nano-composite structures and low surface energy materials. Preparation involved dissolving alkaline solids (carbide slag and decarbonized fly ash), producing carbonated fly ash (CFA) through mineralization reactions, and modifying with fluoroalkylsilane (FAS). Performance indicators studied included wettability, compressive strength, water absorption, anti-chloride ions penetration, frost resistance, and microstructure. Results indicated that higher CFA and FAS contents led to increased water contact angles and improved durability. Compared to control mortar, the superhydrophobic mortar showed about a 70% reduction in water absorption, an 80.84% decrease in chloride ions diffusion coefficient, and after 56 freeze-thaw cycles, mass loss rates and relative dynamic modulus loss rates within 3% and 3%–8.42%, respectively. Enhancements are attributed to the synergistic effect of nano-CaCO₃ on CFA surfaces and surface energy reduction from FAS modification. This work provides valuable information for the development of superhydrophobic mortars with integrated micro- and nano-structures, broadening the application prospects of superhydrophobic cementitious materials.

中文翻译：

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一种碳隔离超疏水砂浆，具有增强的抗氯离子渗透性和抗冻性

超疏水水泥基复合材料是有效缓解混凝土建筑物因外部渗水而导致长期性能恶化的潜在候选材料。然而，传统的超疏水改性会导致抗压强度显著降低。为了解决这个问题，通过微纳米复合结构和低表面能材料的协同作用，开发了一种碳隔离超疏水砂浆，其水接触角为 153°–162°，28 天抗压强度提高了约 10 MPa。制备过程包括溶解碱性固体（碳化物渣和脱碳粉煤灰），通过矿化反应生产碳酸粉煤灰 （CFA），以及用氟烷基硅烷 （FAS） 进行改性。研究的性能指标包括润湿性、抗压强度、吸水率、抗氯离子渗透性、抗冻性和微观结构。结果表明，较高的 CFA 和 FAS 含量导致水接触角增加并提高耐久性。与对照砂浆相比，超疏水砂浆的吸水率降低了约 70%，氯离子扩散系数降低了 80.84%，经过 56 次冻融循环后，质量损失率和相对动模量损失率分别在 3% 和 3%–8.42% 之间。纳米 CaCO₃ 对 CFA 表面的协同作用和 FAS 改性引起的表面能降低归因于增强。本工作为开发具有集成微纳结构的超疏水砂浆提供了有价值的信息，拓宽了超疏水胶凝材料的应用前景。