New paradigm in concrete durability: combined damage mechanisms, virtual testing, and artifical intelligence modeling of service life performance

混凝土基础设施对加拿大的经济增长、国际竞争力和整体生活质量至关重要。钢筋混凝土（RC）结构在现场受到多种变质剂的联合破坏，这些变质剂往往以协同的方式起作用。然而，耐久性的标准试验方法继续使实验室混凝土样品一次遭受一种劣化机制，以便使混凝土混合物符合复杂暴露制度的要求，这与单参数实验室试验完全不同。因此，尽管混凝土技术有了新的发展，但钢筋混凝土结构仍在过早地恶化。再加上目前的延期维修和预算限制，这造成了大量积压的恶化的民用基础设施，造成了国家财富的真正流失。该研究项目将(i)研究复合损伤机制对混凝土的协同效应，（ii）为这种复合损伤机制建立知识数据库，为复杂现场暴露条件下混凝土的生命周期性能创建基于人工智能的预测模型，以及（iii）将这些知识纳入基于性能的耐久性设计工具中。这个新颖的研究项目源于一种范式的转变，即认为未来混凝土耐久性设计的标准测试是基于性能的，使用人工智能模型，可以解释RC结构在现场的真实复杂暴露，并通过计算机模拟进行。该研究的预期影响是至关重要的，因为未来的混凝土结构设计可以充分解决在现场作用于混凝土的复杂损伤机制，从而减轻RC结构的过早劣化并防止相关的经济损失。此外，未来混凝土的标准耐久性测试可以使用实际现场暴露的快速计算机模拟来进行，从而节省时间和金钱。七名博士和三名MESc学生将在未来五年内接受这项新研究的培训。所申请的NSERC资金对于维持和加速申请人的研究计划，并提高其在该领域的国际领导地位至关重要。

Concrete infrastructure is essential for Canada's economic growth, international competitiveness, and overall quality of life. Reinforced Concrete (RC) structures are subjected in-situ to the combined damage of several deterioration agents often acting in a synergistic manner. Yet, standard test methods for durability continue to subject laboratory concrete specimens to one deterioration mechanism at a time in order to qualify concrete mixtures for complex exposure regimes that are quite different from the single-parameter lab tests. Thus, despite new developments in concrete technology, RC structures continue to deteriorate prematurely. Added to ongoing deferred maintenance and budgetary constraints, this has created a colossal backlog of deteriorated civil infrastructure, imposing a veritable drain of national wealth. This research program will (i) investigate the synergistic effects of combined damage mechanisms on concrete, (ii) build knowledge databases for such combined damage mechanisms to create predictive artificial intelligence-based models for the life cycle performance of concrete subjected to complex field exposure regimes, and (iii) incorporate this knowledge into performance-based durability design tools. This novel research program stems from a paradigm shift which perceives the future standard tests for the durability design of concrete to be performance-based, using artificial intelligence models that can account for the real complex exposure of RC structures in-situ, and conducted via computer simulations. The anticipated impact of the research is paramount since the future design of concrete structures can adequately address the complex damage mechanisms acting on concrete in the field, thus mitigating the premature deterioration of RC structures and preventing the associated economic losses. Also, future standard durability tests for concrete can be carried out using rapid computer simulations of actual field exposure, thus saving time and money. Seven PhD and three MESc students will be trained over the next five years in this novel research. The requested NSERC funds are vital to sustain and accelerate the applicant's research program, and to enhance his international leadership in this field.