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出现可能破坏其性能的缺陷。传统的维护程序依赖于定期检查，这是耗时，劳动密集型，成本高，主观性强。永久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感知水泥材料，可用作长期监测混凝土结构（如桥面）的传感器。水泥基传感器通过将导电碳纤维和纳米管掺入水泥浆中制备，是自感测的，因为施加的应变的变化对应于材料电阻率的成比例变化。水泥传感器特别有吸引力，因为它们相似的物理和机械特性允许无缝安装和兼容性。传感器可以嵌入结构中进行局部感测，或者作为薄覆盖层或“感测皮肤”应用，以空间映射应变和缺陷。先前的研究已经成功地证明了水泥传感器的应变传感能力。该多学科研究计划将通过四个短期目标采取关键的后续步骤，以实现现场实施：（1）开发和建立水泥传感器的标准制造方法并检查其耐久性：（2）量化复杂负载和外部环境因素对传感器响应的影响;（3）开发水泥敏感皮肤，并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水泥传感器/皮肤的使用。从长远来看，该研究将评估水泥传感器的现场性能，并开发一个决策框架，将传感器输出转化为及时和适当的维护决策。这项研究有可能彻底改变混凝土结构的监测方式，提供一个更便宜，更兼容的替代电流传感设备。更重要的是，水泥传感皮肤将使全场损伤检测与传统传感器提供的离散测量。通过这些应用程序，加拿大人可以从安全，弹性和智能的基础设施中受益。该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，并进行先进的数值分析。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.