Chidiac Samir E, Reda Mouna A
Department of Civil Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L7, Canada.
Materials (Basel). 2023 Mar 16;16(6):2379. doi: 10.3390/ma16062379.
Autonomous healing is a very promising technique in self-healing concrete systems. For capsules to achieve their anticipated performance, they should be able to survive the harsh mixing conditions of concrete, yet rupture upon concrete cracking. At present, there are no standard test methods, either experimental or analytical, for determining the capsule survival rate during concrete mixing. This study investigates the correlation between the capsules' shell properties, concrete rheological properties, the capsules' external forces, and capsule survival rate during concrete mixing. Finite element and statistical modeling techniques were employed to evaluate the capsule performance and predict the survival rate of capsules during concrete mixing, with 68% confidence. The results revealed that the capsules' survivability during concrete mixing is highly influenced by the capsule's radius-to-thickness ratio, the rheological properties of the fresh concrete, the average-paste-thickness (APT) of the concrete mix, the aggregate content and angularity, and the speed of the mixer. In brief, capsules with a radius-to-thickness ratio between 30 and 45 are likely to survive concrete mixing and yet still rupture upon concrete cracking.
自主愈合是自愈合混凝土系统中一项非常有前景的技术。为使胶囊实现预期性能，它们应能在混凝土严苛的搅拌条件下存活，但在混凝土开裂时破裂。目前，尚无用于确定混凝土搅拌过程中胶囊存活率的标准试验方法，无论是试验性的还是分析性的。本研究调查了胶囊的外壳性能、混凝土流变性能、胶囊所受外力与混凝土搅拌过程中胶囊存活率之间的相关性。采用有限元和统计建模技术来评估胶囊性能，并以68%的置信度预测混凝土搅拌过程中胶囊的存活率。结果表明，混凝土搅拌过程中胶囊的存活能力受胶囊的半径与厚度之比、新拌混凝土的流变性能、混凝土混合料的平均浆体厚度（APT）、骨料含量和棱角性以及搅拌机速度的影响很大。简而言之，半径与厚度之比在30至45之间的胶囊有可能在混凝土搅拌过程中存活，但仍会在混凝土开裂时破裂。
