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

本研究开发了一种单点解决方案，同时解决了通过相变效应引起的混凝土元件劣化的能源效率和热损伤问题。相变材料（PCMs）具有合适的相变温度和焓，可以使混凝土等被动系统提供与温度相关的热能储存和释放。这种相变行为有利于：(i)限制温度上升和相关的变形和应力，以减少混凝土元件热开裂的风险；（ii）通过pcm的热量吸收和释放，促进建筑物内部环境温度的调节。材料尺度上的一系列相关研究包括与水泥水化和相变相关的热特征表征，混凝土中所选PCM的输送策略及其生存能力，以及复合材料作为PCM类型、体积和分散程度的函数的热力学评估。在系统规模上，研究将评估pcm在限制混凝土构件的热开裂和提高混凝土外壳的能源效率方面的能力。对材料和系统级相互作用的详细了解将有助于将pcm -混凝土复合材料的结构-工程特性关系联系起来。多物理场设计方法提供了对材料响应的更好理解，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能量挑战提供了动态的解决方案。建筑能耗的减少以及由此导致的建筑HVAC负荷从高峰时间转移到非高峰时间，使电网效率得以实现并合理化。利用自适应相变解决方案来限制受约束混凝土中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久性做出整体贡献，本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关于节能和抗损伤材料设计的重要多学科问题。还将为初高中学生开发节能建筑材料模块。将通过科学出版物和报告、工业讲习班和专业教育课程，迅速向更广泛的研究和实践界传播这项研究。

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.