Mao Qianjin, Chen Jiayi, Wu Wenwen, Li Runfeng, Shi Shuqing, Wang Ziming, Cui Suping
Faculty of Materials and Manufacturing, Key Laboratory of Advanced Functional Materials, Ministry of Education of China, Beijing University of Technology, Beijing 100124, China.
State Key Laboratory of Solid Waste Reuse for Building Materials, Beijing Building Materials Academy of Science Research, Beijing 100041, China.
Polymers (Basel). 2023 Jan 13;15(2):428. doi: 10.3390/polym15020428.
Concrete cracking has a negative impact on the durability of the structure. Pre-implanting microcapsules containing healing agents into the concrete are expected to induce the cracks to self-heal. However, the self-healing effect can potentially be influenced by several environmental conditions, thus limiting its applications. To address these challenges, we developed a new type of water-absorbing microcapsules, using calcium alginate hydrogel as the wall material and an adhesive epoxy polymer as the core material, to improve the self-healing adaptability in complex and changing environments. We explored the healing properties and mechanism of cementitious materials containing microcapsules under various environmental conditions. The experimental results showed that the water-absorbent microcapsules exhibit multiple self-healing effects under different external conditions: (1) in an anhydrous environment, fissures prompted the activation of microcapsules, and the epoxy polymer flowed out to seal the cracks. (2) When exposed to water, the microcapsules inflated to form a seal around the fissures. (3) The microcapsules facilitated the autogenous healing of cracks in the cementitious material when wet and dry conditions were alternated. The three self-healing mechanisms worked synergistically and contributed to the effective restoration of the impermeability and strength of concrete under different environments. Particularly, the recovery of compressive strength and impermeability exceeded 100% when the microcapsule content was 4% and the pre-pressure was 40% of f.
混凝土开裂对结构耐久性有负面影响。将含有修复剂的微胶囊预先植入混凝土中有望使裂缝自行愈合。然而，自愈合效果可能会受到多种环境条件的影响，从而限制了其应用。为应对这些挑战，我们开发了一种新型吸水微胶囊，以海藻酸钙水凝胶为壁材，以粘性环氧聚合物为芯材，以提高在复杂多变环境中的自愈合适应性。我们探索了含微胶囊的胶凝材料在各种环境条件下的愈合特性和机理。实验结果表明，吸水微胶囊在不同外部条件下呈现多种自愈合效果：（1）在无水环境中，裂缝促使微胶囊活化，环氧聚合物流出以密封裂缝。（2）当暴露于水时，微胶囊膨胀以在裂缝周围形成密封。（3）当干湿条件交替时，微胶囊促进了胶凝材料中裂缝的自愈合。这三种自愈合机制协同作用，有助于在不同环境下有效恢复混凝土的抗渗性和强度。特别是，当微胶囊含量为4%且预压力为f的40%时，抗压强度和抗渗性的恢复超过100%。
