Mao Qianjin, Chen Jiayi, Qi Wenjing, Liu Hui, Wang Ziming, Cui Suping
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Advanced Functional Materials, Ministry of Education of China, Beijing University of Technology, Beijing 100124, China.
Materials (Basel). 2022 Jan 23;15(3):847. doi: 10.3390/ma15030847.
Self-healing cementitious materials are a promising means for ensuring sustainable concrete infrastructure and promoting long-term service lives. To obtain microcapsules that are versatile in varying environments, in this study, absorbing microcapsules with calcium alginate as the shell and epoxy resin as the core were prepared. The absorbing microcapsules exhibit self-healing and can reduce the shrinkage of cementitious materials. Volume changes of the microcapsules in the hardened paste with increasing hydration age were observed using three-dimensional X-ray computed tomography. In the hardened cement paste with a water-cement ratio of 0.29, the absorption of the microcapsules lasted for several days, and the release of water lasted for 28 days. The absorption of microcapsules affected the fluidity of cement paste, and it was significantly weakened and delayed due to the lower absorption rate. The addition of absorbing microcapsules significantly reduced the autogenous and drying shrinkage of mortars. For microcapsules with a core content of 55% added at 3.5% of cement weight, autogenous shrinkage was almost eliminated. Most importantly, the addition of absorbing microcapsules could achieve a certain degree of recovery of compressive strength as well as satisfactory recovery of impermeability in dry and wet environments.
自愈合水泥基材料是确保混凝土基础设施可持续性和延长其长期使用寿命的一种有前景的方法。为了获得在不同环境中都具有通用性的微胶囊，在本研究中，制备了以海藻酸钙为壳、环氧树脂为芯的吸收性微胶囊。这种吸收性微胶囊具有自愈合能力，并且可以减少水泥基材料的收缩。使用三维X射线计算机断层扫描观察了硬化浆体中微胶囊随水化龄期增加的体积变化。在水灰比为0.29的硬化水泥浆体中，微胶囊的吸收持续了几天，而水分释放持续了28天。微胶囊的吸收影响了水泥浆体的流动性，并且由于吸收率较低，其流动性显著减弱且延迟。添加吸收性微胶囊显著降低了砂浆的自收缩和干燥收缩。对于以水泥重量的3.5%添加的芯含量为55%的微胶囊，自收缩几乎消除。最重要的是，添加吸收性微胶囊可以在一定程度上实现抗压强度的恢复，以及在干湿环境下达到令人满意的抗渗性恢复。
