Design of "Crack-free" Concrete Materials with Robust Self-healing Functionality

这项拨款为开发几乎“无裂缝”的混凝土材料提供资金，这些材料能够通过自密封多孔裂缝和损伤后自动再生机械性能来提高材料耐久性和延长结构使用寿命。这将通过检验最能促进自我修复的物理和化学材料要求和环境暴露的实验研究来完成。在典型结构使用条件下，基于裂纹萌生和扩展细观力学的材料设计，将裂缝宽度控制在60 m以下。纳米和微尺度的离子传输、晶体形成和生长成自愈产品的现象将被确定。支持这项工作的是一套现有的和新开发的实验测试，以评估自我修复的可靠性、质量和可重复性。这些测试包括动态模量测量、单轴拉伸测试、透水性测试、纳米压痕和XEDS。因此，在运输和机械性能方面的自愈程度将被确定。如果成功，这项研究将为设计几乎“无裂缝”的坚固混凝土材料提供系统的方法。这对美国产生了重大的经济、社会和环境影响，因为它提高了耐久性，减少了桥梁和道路等基础设施的维护需求和成本。除了耐久性之外，自愈混凝土通过在损坏后再生，在结构安全性和成本效益方面提供了更高的性能，成为工程师负责创建符合越来越高要求的结构的有力工具。这项研究的影响不仅在建筑工程师中，而且通过开发强大的自修复复合材料的方法，在更大的工程设计界中传播了重大的设计范式转变。

This grant provides funding for the development of virtually "crack-free" concrete materials capable of elevating material durability and extending structural service life by self-sealing porous cracks and autogenously regenerating mechanical performance after damage. This will be accomplished through experimental studies examining the physical and chemical material requirements and environmental exposures that best promote self-healing. Material design based on micromechanics of crack initiation and propagation to control crack width to below 60 m under typical structural service conditions will be emphasized. Nano and microscale phenomena of ion transport, crystal formation and growth into self-healed products will be determined. Supporting this work is a set of existing and newly developed experimental tests to evaluate the reliability, quality and repeatability of self-healing. These tests include dynamic modulus measurements, uniaxial tensile test, water permeability test, nano-indentor and XEDS. As a result, the extent of self-healing both in transport as well as in mechanical properties will be determined.If successful, this research will provide a systematic methodology for designing robust concrete material which is virtually "crack-free." This have significant economic, social and environmental impacts on the United States, through enhancement of the durability and reduction of maintenance needs and cost of infrastructures such as bridges and roadways. Apart from durability, self-healing concretes offer higher performance in structural safety and cost-effectiveness by regenerating after damage, becoming a powerful tool for engineers charged to create structures conforming to increasingly higher requirements. The impacts of this research look to promulgate a significant design paradigm shift not only among construction engineers, but the larger engineering design community through methods for development of robust self-healing composites.