Zhang Kun, Wang Kaiqiang, Liu Zhimao, Ye Zhiwu, Zhang Baifa, Lu Deng, Liu Yi, Li Lijuan, Xiong Zhe
China Construction Third Engineering Bureau Group Co., Ltd., Wuhan 430074, China.
School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, China.
Materials (Basel). 2022 Jul 14;15(14):4911. doi: 10.3390/ma15144911.
The use of seawater to prepare geopolymers has attracted significant research attention; however, the ions in seawater considerably influence the properties of the resulting geopolymers. This study investigated the effects of magnesium salts and alkaline solutions on the microstructure and properties of ground-granulated-blast-furnace-slag-based geopolymers. The magnesium salt-free NaSiO-activatied geopolymer exhibited a much higher 28 d compressive strength (63.5 MPa) than the salt-free NaOH-activatied geopolymer (31.4 MPa), with the former mainly containing an amorphous phase (C-(A)-S-H gel) and the latter containing numerous crystals. MgCl·6HO addition prolonged the setting times and induced halite and Cl-hydrotalcite formation. Moreover, mercury intrusion porosimetry and scanning electron microscopy revealed that the NaSiO-activated geopolymer containing 8.5 wt% MgCl·6HO exhibited a higher critical pore size (1624 nm) and consequently, a lower 28 d compressive strength (30.1 MPa) and a more loosely bound geopolymer matrix than the salt-free geopolymer. In contrast, MgSO addition had less pronounced effects on the setting time, mineral phase, and morphology. The NaSiO-activated geopolymer with 9.0 wt% MgSO exhibited a compressive strength of 42.8 MPa, also lower than that of the salt-free geopolymer. The results indicate that Cl is more harmful to the GGBFS-based geopolymer properties and microstructure than SO is.
利用海水制备地质聚合物已引起了广泛的研究关注；然而，海水中的离子会对所得地质聚合物的性能产生显著影响。本研究考察了镁盐和碱性溶液对磨细粒化高炉矿渣基地质聚合物微观结构和性能的影响。无镁盐的硅酸钠活化地质聚合物的28天抗压强度（63.5MPa）远高于无盐的氢氧化钠活化地质聚合物（31.4MPa），前者主要含有非晶相（C-(A)-S-H凝胶），后者含有大量晶体。添加MgCl₂·6H₂O会延长凝结时间，并诱导石盐和氯水滑石的形成。此外，压汞法和扫描电子显微镜显示，含有8.5wt%MgCl₂·6H₂O的硅酸钠活化地质聚合物具有更高的临界孔径（1624nm），因此，其28天抗压强度更低（30.1MPa），且地质聚合物基体的结合更松散。相比之下，添加MgSO₄对凝结时间、矿物相和形态的影响较小。含有9.0wt%MgSO₄的硅酸钠活化地质聚合物的抗压强度为42.8MPa，也低于无盐地质聚合物。结果表明，Cl对基于磨细粒化高炉矿渣的地质聚合物性能和微观结构的危害比SO₄更大。
