Van den Heede Philip, Van Belleghem Bjorn, Alderete Natalia, Van Tittelboom Kim, De Belie Nele
Magnel Laboratory for Concrete Research, Department of Structural Engineering, Faculty of Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 904, Ghent B-9052, Belgium.
Strategic Initiative Materials (SIM vzw), project ISHECO within the program 'SHE', Technologiepark Zwijnaarde 935, Ghent B-9052, Belgium.
Materials (Basel). 2016 Apr 26;9(5):311. doi: 10.3390/ma9050311.
Given their low tensile strength, cement-based materials are very susceptible to cracking. These cracks serve as preferential pathways for corrosion inducing substances. For large concrete infrastructure works, currently available time-consuming manual repair techniques are not always an option. Often, one simply cannot reach the damaged areas and when making those areas accessible anyway (e.g., by redirecting traffic), the economic impacts involved would be enormous. Under those circumstances, it might be useful to have concrete with an embedded autonomous healing mechanism. In this paper, the effectiveness of incorporating encapsulated high and low viscosity polyurethane-based healing agents to ensure (multiple) crack healing has been investigated by means of capillary absorption tests on mortar while monitoring the time-dependent water ingress with neutron radiography. Overall visual interpretation and water front/sample cross-section area ratios as well as water profiles representing the area around the crack and their integrals do not show a preference for the high or low viscosity healing agent. Another observation is that in presence of two cracks, only one is properly healed, especially when using the latter healing agent. Exposure to water immediately after release of the healing agent stimulates the foaming reaction of the polyurethane and ensures a better crack closure.
由于其抗拉强度较低，水泥基材料非常容易开裂。这些裂缝成为腐蚀诱导物质的优先通道。对于大型混凝土基础设施工程，目前可用的耗时人工修复技术并非总是可行的选择。通常，人们根本无法到达受损区域，而当无论如何要使这些区域可进入时（例如，通过重新规划交通），所涉及的经济影响将是巨大的。在这种情况下，具有嵌入式自主修复机制的混凝土可能会很有用。在本文中，通过对砂浆进行毛细吸收试验，并利用中子射线照相术监测随时间变化的水分进入情况，研究了掺入封装的高粘度和低粘度聚氨酯基修复剂以确保（多次）裂缝修复的有效性。整体视觉解释、水前沿/样品横截面积比以及代表裂缝周围区域的水分布及其积分，并未显示出对高粘度或低粘度修复剂的偏好。另一个观察结果是，在存在两条裂缝的情况下，只有一条能得到妥善修复，尤其是使用后一种修复剂时。修复剂释放后立即接触水会刺激聚氨酯的发泡反应，并确保更好的裂缝闭合。
