快速响应型防水砂浆自修复微胶囊设计与性能

Design and Performance of Rapid Response Self-healing Microcapsule for Waterproof Mortar

摘要:

针对防水砂浆开裂导致的寿命问题，研发了一种自修复微胶囊，其直径为3.0~3.5 mm，芯材为磷酸镁水泥、海藻酸钠和聚乙二醇，壁材为环氧树脂复合硫铝酸盐水泥；将自修复微胶囊掺进水泥砂浆，并研究了其自修复效果及机制.结果表明：自修复微胶囊防水耐碱性能较好，能与硅酸盐基体产生紧密的界面过渡区，促使裂缝沿微胶囊发展；微胶囊破损后海藻酸钠遇水迅速膨胀形成水凝胶网络结构，15 min内膨胀面积超200%，可以初步封堵裂缝，随后磷酸镁水泥水化，于水凝胶中持续作用，加强裂缝封闭；该微胶囊3 d内可修复200 μm以下的裂缝，7 d内可修复450 μm的宽裂缝，7 d内抗渗性能可恢复至76%，自修复快速且高效.

Abstract:

A novel self-healing microcapsule with a diameter of 3.0 to 3.5 mm was developed to tackle the lifespan issues due to waterproof mortar cracking. The core of the microcapsule was composed of magnesium phosphate cement， sodium alginate， and polyethylene glycol， encapsulated within a shell of epoxy resin composite sulfoaluminate cement. The self-healing microcapsules were incorporated into the cement mortar， and their self-healing effects and mechanisms were studied. The results indicate that the self-healing microcapsules exhibit good waterproof and alkali-resistant properties， facilitating the formation of a cohesive interfacial transition zone with the silicate-based substrate and directing crack propagation along their surface. Upon damage， the sodium alginate component within the microcapsules undergoes rapid hydration-induced swelling upon contact with water， forming a robust hydrogel network structure with an expansion area exceeding 200% within 15 minutes， thereby forming the initial sealing of cracks. Subsequently， the magnesium phosphate cement undergoes hydration within the hydrogel matrix， continuously reinforcing the crack sealing process. These innovative microcapsules demonstrate the capability to repair cracks with widths of up to 200 μm within a period of 3 days and cracks as wide as 450 μm within 7 days. Furthermore， the impermeability of self-healing microcapsules can be restored to 76% within 7 days， highlighting their rapid and highly efficient self-healing.