Dealing with critical aging infrastructures: challenges and research needs

民用基础设施对社会至关重要，它连接着国家的企业、社区和人民，推动经济发展，提高人类的生活质量。一方面，在加拿大和世界范围内，建于20世纪60年代至80年代的许多老化结构，由于碱集料反应（AAR）、钙矾石延迟形成（DEF）、硫酸盐侵蚀、钢腐蚀、冻融循环等多种有害破坏机制，呈现出明显的受损迹象。为了保证其在设计使用寿命内的性能，甚至延长其预期寿命，工程师需要高效可靠的工具来将受影响材料（诊断）的机械性能、物理完整性和耐久性的降低与其结构后果联系起来。这些信息对于确定进一步恶化的可能性（预后）和选择及时有效的管理行动至关重要。另一方面，考虑到对可持续和弹性基础设施的需求，以及在未来几十年保护自然资源的压力，必须使用生态高效/环保材料建造新结构，同时优化工业过程和已达到预期使用寿命的基础设施拆除所产生的材料的回收利用。因此，当前研究计划的目标在于开发A)用于老化混凝土基础设施的状态评估和未来行为预测的优化创新工具；B)技术知识，用于理解材料的破坏与受各种病害影响的混凝土构件/结构的结构性能/行为之间的相互作用；C)针对陷入困境、老化的基础设施的时间依赖性能模型，允许对此类结构采取可靠和及时的管理行动；D)生态高效/环保的高性能混凝土混合设计，以促进建筑业的可持续和弹性发展。拟议的研究结果将有助于开发测试程序、模型和行为规律，以及可靠的管理建议/实践，以延长新混凝土结构的设计寿命或老化混凝土结构的使用寿命。

Civil infrastructure is critical for society, connecting the nation's businesses, communities and people, driving the economy and improving the quality of life of human beings. On one hand, numerous aging structures built in the 1960's to 1980's in Canada and worldwide present clear signs of distress caused by numerous harmful damage mechanisms such as alkali-aggregate reaction (AAR), delayed ettringite formation (DEF), sulfate attack, steel corrosion, freezing and thawing cycles, etc. To guarantee performance over their designed service lives, or even to extend their expected life spans, engineers need efficient and reliable tools for correlating the reductions in mechanical properties, physical integrity and durability of affected materials (diagnosis) to their structural consequences. This information is critical in determining the potential for further deterioration (prognosis) and selecting timely and efficient management actions. On the other hand, considering the need for sustainable and resilient infrastructure, as well as the pressure to preserve natural resources for the decades to come, it is essential that new structures are built with eco-efficient/environmentally friendly materials, while optimizing the recycling of materials resulting from industrial processes and demolition of infrastructure having reached their expected service life. Therefore, the objectives of the current research program lie in the development of A) optimized innovative tools for condition assessment and prediction of future behaviour of aging concrete infrastructure; B) technical knowledge for understanding the interactions between the material's distress and the structural performance/behaviour of concrete members/structures affected by various pathologies; C) time-dependent performance models for distressed, aging infrastructure allowing for reliable and timely management actions for such structures; and D) eco-efficient/environmentally friendly high performance concrete mix designs for the sustainable and resilient development of the construction industry. The results of the proposed research will contribute to the development of testing procedures, models and behavioural laws as well as reliable management recommendations/practices for either extending the design life of new concrete constructions or the service lives of aging concrete structures.