Self-sensing cementitious composites for infrastructure health monitoring

加拿大和世界其他地区老化的基础设施容易受到可能破坏其性能的缺陷的影响。传统的维护程序依赖于定期检查，这是耗时、劳动密集、昂贵和高度主观的。永久性监测系统使用先进的传感技术提供有关结构状态的实时信息，以便及时发现和修复缺陷。这项及时的研究重点是开发自传感胶凝材料，可以用作传感器长期监测混凝土结构，如桥面。水泥传感器是通过在水泥浆中掺入导电碳纤维和纳米管制备的，由于施加应变的变化与材料电阻率的比例变化相对应，因此具有自传感功能。水泥传感器特别具有吸引力，因为它们具有相似的物理和机械性能，可以实现无缝安装和兼容性。传感器可以嵌入到结构中进行局部传感，或者作为薄覆盖层或“传感皮肤”应用于空间映射应变和缺陷。以往的研究已经成功地证明了胶凝传感器的应变传感能力。这一多学科研究项目将通过四个短期目标为现场实施采取关键的下一步措施：(1)开发和建立胶凝传感器的标准制造方法并检查其耐久性；(2)量化复杂载荷和外部环境因素对传感器响应的影响；(3)开发胶凝传感表皮，利用电阻率的空间分布来检测应变和损伤；(4)通过大规模试验验证胶凝传感器/皮肤的使用。从长远来看，该研究将评估胶凝传感器的现场性能，并制定决策框架，将传感器输出转化为及时和适当的维护决策。这项研究通过提供一种更便宜、更兼容的替代现有传感设备，有可能彻底改变混凝土结构的监测方式。更重要的是，与传统传感器提供的离散测量相比，胶凝传感皮肤可以实现全场损伤检测。通过这些应用，加拿大人可以从安全、有弹性和智能的基础设施中受益。拟议的计划将创造一个充满活力的研究环境，研究生和本科生合作进行尖端的实验室实验和执行先进的数值分析。训练有素的高素质人员将专门掌握必要的技能，以实施和管理监测加拿大基础设施健康状况的传感系统。

The aging infrastructure in Canada and other parts of the world is susceptible to defects that may disrupt its performance. Traditional maintenance procedures rely on periodic inspections, which are time-consuming, labor-intensive, costly and highly subjective. Permanent monitoring systems use advanced sensing technologies to provide real-time information about the state of structures so that deficiencies can be detected and repaired promptly. This timely research focuses on developing self-sensing cementitious materials that can be used as sensors in long-term monitoring of concrete structures such as bridge decks. Cementitious sensors, prepared by incorporating conductive carbon fibres and nanotubes in cement paste, are self-sensing because changes in applied strain correspond to proportional changes in the electrical resistivity of the material. Cementitious sensors are particularly attractive because their similar physical and mechanical properties allow for seamless installations and compatibility. The sensors can be embedded in the structure for local sensing, or applied as a thin overlay or “sensing skin” to spatially map strains and defects. Previous research has successfully demonstrated the strain-sensing capability of cementitious sensors. This multidisciplinary research program will take the critical next steps towards field implementation through four short term objectives: (1) Developing and establishing standard fabrication methods for cementitious sensors and examining their durability; (2) Quantifying the effects of complex loading and external environmental factors on sensor response; (3) Developing cementitious sensing skins and using the spatial distribution of resistivity to detect strain and damage; (4) Validating the use of cementitious sensors/skins through large-scale tests. In the long-term, the research will evaluate the field performance of cementitious sensors and develop a decision-making framework that translates sensor outputs to timely and appropriate maintenance decisions. This research has the potential to revolutionize the way concrete structures are monitored by providing a less expensive and more compatible alternative to current sensing devices. More importantly, cementitious sensing skins will enable full-field damage detection versus discrete measurements offered by conventional sensors. With these applications, Canadians can benefit from safe, resilient and smart infrastructure. The proposed program will create a vibrant research environment where graduate and undergraduate students collaboratively conduct cutting-edge laboratory experiments and perform advanced numerical analyses. The trained highly qualified personnel will specialize in the necessary skills to implement and manage sensing systems that monitor the health of Canadian infrastructure.