In this study, the impact of alkaline solutions composed of various Na2SiO3/NaOH ratio and NaOH molarity on the strength, chloride ingress and chloride binding capacity of fly ash (FA) and ground granulated blast furnace slag (GGBS) based alkali activated concrete (AAC) was investigated. The microstructural properties of alkali activated binders (AAB) composites was also studied to understand its influence on the chloride permeability of AAC. Chloride permeability of concrete was tested by using the rapid chloride penetration test (RCPT) and by immersing concrete in NaCl solution (ASTM C1556). The compressive strength, chloride ingress and chloride binding capacity of AAC was compared with Portland cement-based concrete (OPC). Results showed that higher Na2O/SiO2 ratio in alkaline solutions resulted in a weak microstructure with, low strength and high chloride ingress. Concrete activated by alkaline solutions with Na2O/SiO2 molar ratio = 1 (±3), exhibited greater compressive strength and resistance to chloride ion penetration. The increase of SiO2 concentration in alkaline solution greatly reduces the binding capacity of AAC while the bound chlorides increased with the NaOH molarity. No chemical chloride binding was observed in AAC but for OPC concrete, calcium salts formed in the microstructure after immersion in NaCl solution. Compared to OPC concrete, AAC showed superior performance in terms of strength and chloride diffusion making it a potential candidate for application in marine structures.

中文翻译：

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碱活化剂中Na2SiO3/NaOH配比对粉煤灰和GGBS基碱活化混凝土显微组织、强度及氯化物进入的影响


本研究研究了由不同 Na2SiO3/NaOH 配比和 NaOH 摩尔浓度组成的碱性溶液对粉煤灰 （FA） 和磨粒化高炉矿渣 （GGBS） 基碱活化混凝土 （AAC） 的强度、氯化物进入量和氯化物结合能力的影响。还研究了碱活化粘合剂 （AAB） 复合材料的微观结构性能，以了解其对 AAC 氯化物渗透性的影响。通过使用快速氯化物渗透测试 （RCPT） 和将混凝土浸入 NaCl 溶液 （ASTM C1556） 来测试混凝土的氯化物渗透性。将 AAC 的抗压强度、氯化物侵入量和氯化物结合能力与波特兰水泥基混凝土 （OPC） 进行了比较。结果表明，碱性溶液中较高的 Na2O/SiO2 比率导致微观结构较弱，强度低，氯化物进入量大。被 Na2O/SiO2 摩尔比 = 1 （±3） 的碱性溶液活化的混凝土表现出更大的抗压强度和抗氯离子渗透能力。碱性溶液中 SiO2 浓度的增加大大降低了 AAC 的结合能力，而结合的氯化物随着 NaOH 摩尔浓度的增加而增加。在 AAC 中未观察到化学氯化物结合，但对于 OPC 混凝土，浸泡在 NaCl 溶液中后，钙盐在微观结构中形成。与 OPC 混凝土相比，AAC 在强度和氯化物扩散方面表现出优异的性能，使其成为海洋结构的潜在候选者。