This study investigated the influence of nano silica (NS) addition on the early‐ and later‐age compressive strengths and durability properties such as sorptivity, drying shrinkage, volume of permeable voids, and rapid chloride permeability, along with microstructural changes, of high‐volume slag (HVS) and high‐volume slag–fly ash (HVS‐FA) blended concrete. The results showed that the addition of NS improved the early‐age (3 days) compressive strength of HVS and HVS‐FA concretes significantly by 34 and 45%, respectively. In addition, the HVS concrete containing 78% blast furnace slag (BFS) gained considerable compressive strengths at later age due to the addition of 2% NS than the control HVS concrete with 80% BFS and showed comparable compressive strengths to ordinary Portland cement (OPC) concrete. On the other hand, the compressive strengths of HVS‐FA concrete containing 67% BFS‐FA blend and 3% NS surpassed OPC concrete at 28 days and exhibited superior strengths at later ages than the OPC concrete. Significant reduction in sorptivity of both HVS and HVS‐FA concretes is observed at 28 and 91 days, respectively, due to the addition of NS. Similar substantial reduction of drying shrinkage, chloride ion permeability, and volume of permeable voids are also witnessed in both HVS and HVS‐FA concretes due to the inclusion of NS than their respective control concretes without NS, and these exhibited better performance than control OPC concrete on most occasions. A denser and compacted interfacial transition zone (ITZ) is also found in the HVS and HVS‐FA concretes due to the addition of a small amount of NS.

中文翻译：

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纳米二氧化硅对高炉渣和高炉渣-粉煤灰掺合混凝土的抗压强度，耐久性和微观结构的影响

这项研究调查了纳米二氧化硅（NS）的添加对高抗压强度的早期和晚期抗压强度和耐久性的影响，例如吸附性，干燥收缩，可渗透空隙的体积和快速的氯离子渗透性以及微观结构变化。体积渣（HVS）和高体积渣-粉煤灰（HVS-FA）混合混凝土。结果表明，添加NS分别使HVS和HVS-FA混凝土的早期（3天）抗压强度分别提高了34％和45％。此外，含78％高炉矿渣（BFS）的HVS混凝土在晚龄时获得了相当高的抗压强度，这是因为与含80％BFS的对照HVS混凝土相比，添加了2％NS所显示的抗压强度，并显示出与普通硅酸盐水泥（OPC）相当的抗压强度） 具体的。另一方面，含有67％BFS-FA共混物和3％NS的HVS-FA混凝土的抗压强度在28天时超过了OPC混凝土，并且在较晚的龄期中表现出比OPC混凝土更高的强度。由于添加了NS，HVS和HVS-FA混凝土的吸水性显着降低，分别在28天和91天。在HVS和HVS-FA混凝土中，由于掺入了NS，它们的干燥收缩率，氯离子渗透性和可渗透空隙的体积也得到了类似的大幅降低，而与不含NS的对照混凝土相比，它们包含了更好的性能。在大多数情况下。由于添加了少量的NS，在HVS和HVS-FA混凝土中也发现了更致密的致密界面过渡区（ITZ）。