CAREER: Linking Pore Structure, Performance, and Material Design of a Sustainable Macroporous Concrete for Multifunctional Applications

增强孔隙率混凝土（EPC）是一种相对较新的混凝土类型，具有比普通孔隙率和孔隙连通性更高的特性，因此有助于诸如雨水径流控制和公路噪声缓解等应用。CAREER方案的基本目标是通过多学科方法，包括立体学方法、断裂特性、多孔介质流动和数学优化，将EPC的孔隙结构特征和性能与其材料设计参数联系起来。二维EPC图像的几何数据将使用随机几何技术进行立体解释，并基于颗粒堆积理论开发了一种新的孔隙度预测方法，以建立材料设计参数与孔隙结构特征之间的相关性。孔隙结构特征将涉及：(i)力学行为，使用包括韧性和强度的断裂准则，从而提供对裂纹钝化和更高空隙率之间竞争的理解；（ii）渗透率使用x射线断层扫描，平面图像的三维重建和分形模型；（iii）污染物保留效率使用多相流理论和重建模型。由于EPC系统需要针对多个性能要求进行设计，因此将使用多目标优化程序来获得一组可行的材料设计参数。这将通过孔隙结构特征促进材料设计与性能之间关系的发展。该CAREER提案将为EPC系统带来一种急需的基于性能的设计方法，并使其能够预测性能。这将有助于开发确定EPC特性的测试方法，并将促进EPC设计从目前采用的试验和错误方法过渡到科学过程。该提案中的教育计划通过基于问题的设计和学习、教学实验课程的开发和K-12扩展计划与研究部分紧密联系在一起。采用“构思-实施-设计-操作”（CDIO）的方法，将基于问题的学习和设计付诸实践，学生将负责设计，构建和评估几个小型EPC测试平台系统。本课程将开设一门实验教学课程，让本科生可以研究与水泥基材料相关的结构性课题。克拉克森现有的GK-12项目将作为一种工具，以EPC作为模型多孔工程材料，强调中学生的动手活动和工程问题解决，从而整合研究和推广。

Enhanced Porosity Concrete (EPC) is a relatively new class of concrete having higher than normal porosity and pore connectivity, thus facilitating applications such as storm water runoff control, and highway noise mitigation. The fundamental objective of this CAREER proposal is to link the pore structure features and performance of EPC to its material design parameters through a multi-disciplinary approach that involves stereological methods, fracture properties, porous media flow, and mathematical optimization. Geometrical data from two dimensional EPC images will be stereologically interpreted using stochastic geometry, and a novel porosity prediction method based on particle packing theory developed to establish correlations between material design parameters and pore structure features. Pore structure features will be related to: (i) mechanical behavior using a fracture criterion that involves both toughness and strength, thus providing an understanding of the competition between crack-blunting and higher void fraction, (ii) permeability using X-ray tomography, three-dimensional reconstruction of planar images, and fractal models, and (iii) pollutant retention efficiency using multi-phase flow theories and reconstructed models. Since EPC systems need to be designed for more than one performance requirement, a multi-objective optimization procedure will be used to arrive at a feasible set of material design parameters. This will facilitate the development of relationships between material design and performance through the pore structure features. This CAREER proposal will result in a much needed performance-based design methodology for EPC systems, and enable predictions of performance. This will aid in the development of test methods to determine EPC properties, and will facilitate the transition of EPC design to a scientific process from the currently employed trial and error methods. The educational plan in this proposal is strongly tied with the research component through problem-based design and learning, development of a teaching lab course, and K-12 outreach program. A conceive-implement-design-operate (CDIO) approach will be used to put the problem-based learning and design into practice where the students will be responsible for designing, constructing, and evaluating a few small EPC test bed systems. A teaching lab course, where the undergraduate students can do research on structured topics related to cement-based materials will be developed. The existing GK-12 program at Clarkson will be used as a vehicle to emphasize hands-on activities and engineering problem solving to middle and high school students using EPC as a model porous engineering material, thus integrating research and outreach.