Phase Change Materials in Concrete: A New Strategy to Improve the Thermal Damage Resistance and Thermal Energy Efficiency of Concrete Structures

本研究开发了一个单点解决方案，同时解决能源效率和热损伤的问题，通过相变效应的混凝土元件的恶化。具有合适相变温度和焓的相变材料（PCM）的结合允许被动系统（诸如混凝土）提供热能的温度关联存储和释放。这种相变行为有利地用于：（i）限制温度上升和相关的变形和应力，以降低混凝土元件中的热开裂风险，以及（ii）通过PCM的热吸收和释放促进建筑物中的内部环境温度的调节。一套相互关联的研究，在材料规模包括表征的热签名相关的水泥水化和相变，交付策略所选择的PCM在混凝土和其生存能力，和热机械评价的复合材料作为PCM类型的函数，体积和分散程度。在系统范围内，研究将评估PCM限制受约束混凝土构件热开裂和提高混凝土外壳能效的能力。材料和系统级的相互作用的详细理解将有助于相关的PCM-混凝土复合材料的结构工程性能的关系。多物理场设计方法提供了对材料响应的更好理解，并促进了这些新型多功能材料在具体应用中的部署。这项研究为建筑环境的充满活力的挑战提供了动态的解决方案。减少建筑物的能源消耗和由此产生的建筑物暖通空调负荷从高峰时间转移到非高峰时间，使电网效率变得合理。 利用自适应相变解决方案来限制受约束混凝土中由环境力引起的热损伤，从而提高结构的使用寿命和耐久性。通过对基础设施的能源效率和耐用性做出全面贡献，这项研究推动了确保可持续建筑环境的新范式。从教育的角度来看，这项研究将培养研究生和本科生对重要的多学科问题有关的节能和耐破坏的材料设计。还将为初中和高中学生开发节能建筑材料模块。将通过科学出版物和介绍、工业讲习班和专业教育课程，向更广泛的研究和实践界迅速传播研究成果。

This research develops a single-point solution to simultaneously address issues of energy efficiency and thermal damage linked deterioration of concrete elements through phase change effects. The incorporation of phase change materials (PCMs) with a suitable phase transition temperature and enthalpy allows a passive system such as concrete to provide temperature-linked storage and release of thermal energy. This phase change behavior is beneficially harnessed to: (i) limit temperature rise and associated deformations and stresses to reduce the risk of thermal cracking in concrete elements and (ii) facilitate the regulation of the internal ambient temperature in buildings through heat absorption and release from PCMs. A suite of interrelated studies at the material-scale comprises the characterization of heat signatures related to cement hydration and phase transformation, delivery strategies for the chosen PCMs in concrete and its survivability, and the thermo-mechanical evaluation of the composite as a function of PCM type, volume and extent of dispersion. At the system-scale, studies will evaluate the ability of PCMs to limit thermal cracking in restrained concrete members and enhance the energy efficiency of concrete enclosures. A detailed understanding of the material- and system-level interactions will help correlate structure-engineering property relationships for the PCM-concrete composite. The multi-physics design approach provides a better understanding of the material response and facilitates the deployment of these novel multi-functional materials in concrete applications. This research provides dynamic solutions to the energetic challenges of the built environment. Reductions in building energy consumption and the resultant shift of the buildings HVAC loads from peak to off-peak hours enables and rationalizes power-grid efficiency. Auto-adaptive, phase change solutions are harnessed to limit thermal damage caused by environmental forces in restrained concretes resulting in improved structural service-life and durability. By making holistic contributions towards the energy efficiency and durability of infrastructure, this research drives a new paradigm in ensuring a sustainable built environment. From an educational perspective, this research will train graduate and undergraduate students on important multi-disciplinary problems pertaining to energy-efficient and damage-resistant material design. Modules on energy efficient construction materials will also be developed for middle and high school students. Rapid dissemination of the research to the broader research and practicing community will be accomplished through scientific publications and presentations, industrial workshops and professional education courses.