水泥及地聚物疏水复合材料的研究现状及分析

Research status and analysis of cement and geopolymer hydrophobic composites

  • 摘要: 混凝土的长期耐久性问题是其面临的主要问题之一,造成耐久性破坏的主要原因是水在混凝土的多孔结构中的迁移,使有害离子更容易进入基材内部。采用超疏水材料对水泥及地聚物进行改性复合处理,赋予其超疏水特性,避免水分在其孔隙中的传输,从而防止有害离子的迁移及侵蚀,增强混凝土的耐久性。本文总结了目前研究当中对于水泥及地聚物胶凝材料超疏水改性方法,包括整体改性和表面改性两种;归纳了整体改性方式中超疏水改性剂加入到水泥及地聚物混凝土中的改性机制,以及与无机物基体中的连接键合方式;概括了目前研究当中表面改性常用的改性方法,包括喷涂法、浸渍法、模板法等,并分析了表面改性机制。与表面改性所得到的超疏水复合涂层相比,整体改性的水泥及地聚物基复合材料在实际应用场景当中具有更大的优势。此外,分析了疏水改性后对复合材料润湿性、防水性、抗压性能以及防腐性能的影响规律,发现其抗压强度降低了约20%~60%。最后,阐述了水泥及地聚物复合材料的疏水改性研究中存在的一些问题并对未来的研究方向进行了展望,建议从体积型超疏水、提高抗压强度、成本控制及疏水外加剂在材料内部实现均匀化分散等方面进行研究。

     

    Abstract: The long-term durability of concrete is one of the main problems it faces, and the main cause of durability damage is the migration of water in the porous structure of concrete, which makes it easier for harmful ions to enter the interior of the substrate. Modifying the cement and geopolymer with superhydrophobic materials is a valid method to avoid the transmission of water, thereby preventing the migration of harmful ions and increased its durability of concrete. This review summarized the superhydrophobic modification methods of cement and geopolymer cementitious materials and categorized into superhydrophobic surface and bulk modification; the modification mechanism of superhydrophobic modifier added to cement and geopolymer and their bonding mode with inorganic matrix in the internal modification method. Besides, the modification methods commonly used for surface modification in the present research are summarized, divided into external coating, maceration, template method, etc., and the surface modification mechanism is analyzed. Compared with the superhydrophobic composite coatings, the monolithically modified cement and geopolymer matrix composites have greater advantages in practical application scenarios. In addition, the effects of hydrophobic modification on the wettability, waterproofing, compressive properties and anti-corrosion properties of composites are concluded, and their compressive strength was reduced by about 20%~60%. Finally, some problems in the research of hydrophobic modification of cement and geopolymer composites are described and the future research direction is prospected, and it is suggested to carry out research on volumetric super-hydrophobicity, improvement of compressive strength, cost control, and homogeneous dispersion of hydrophobic admixture inside the material.

     

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