氧化石墨烯对水泥基复合材料微观结构的调控机制及与性能的相关性

At present, the main issues of high performance cement based composites（HPC） is poor toughness and producing cracking and penetration easily. Now the major approach to resolve them at home and abroad is to enhance the intensity and toughness by adding high performance fibers in concrete. But the problems of high cracking and permeation problem still exists today. Based on the result of the previous studies, a new idea is proposed by applicant to reinforce the strength, especially reinforcing flexibility, by using the graphite oxide (GO) with high strength and high flexibility and modified microstructure of HPC by adjusting function of GO on concrete microstructure. The regulation and influence of GO on the microscopic structure and properties of HPC were investigated through studied of the composition proportion, size or shape of cement hydration products, the microstructure of its interface transition layers of aggregates and gel and the characteristic of pore structure. Meanwhile, the capacity to regulate the microstructure and properties of HPC was improved through the study of the relationship of controlled oxidation and controlled scattered and functional groups of GO. The mechanism and regulation of controlling of microstructure of HPC with GO was revealed and the relationship between the microstructure and macroscopic performance of HPC was established. The innovation in the project is remarkably improving the mechanical properties, especially toughness and crack resistance, by changing the HPC microstructure using GO regulation on composition and shape of cement hydration products. The achievement of this study could provide the theoretic support and methodical guidance for to design an ideal performance concrete by regulation on the concrete microstructure with GO.

目前高性能水泥基复合材料（HPC）存在的主要问题是韧性差、容易裂缝和渗透，国内外解决的主要方法是用高性能纤维进行增强增韧，但是裂缝渗透的问题依然存在。申请者在前期研究的基础上，提出了利用氧化石墨烯（GO）的高强度和高柔韧性以及对混凝土微观结构的调控作用，显著提高混凝土的性能特别是韧性和抗裂缝的性能。通过研究GO对水泥水化产物的组成与形状、集料与凝胶体间过渡层结构、孔结构及对性能的影响，揭示GO对HPC的微观结构及性能特别是韧性影响的规律。通过GO的可控氧化调控分散和功能化程度，提高GO调控HPC微观结构和性能的能力，揭示GO调控HPC结构的机理和规律，建立HPC微观结构与性能的关系。本项目创新之处是利用纳米GO对水泥水化产物组成和形状的调控作用改变水泥基复合材料的微观结构，显著提高HPC的力学性能特别是韧性及抗裂缝的能力，为通过调控混凝土的微观结构构筑理想性能的水泥基复合材料提供理论指导。

项目背景：水泥基复合材料依然是目前世界上用量最大、用途最广的建筑材料，存在主要问题是高脆性、易裂缝和渗漏，影响到了其力学性能和使用寿命。目前的解决方法是依靠增强增韧材料，但是依然不能解决存在的问题。这些问题的根源在于水泥产物及聚集态的微观结构不规整。.主要研究内容：进行了氧化石墨烯（GO）对水泥基复合材料微观结构的调控机制及与性能的相关性的研究，（1）研究了GO可控分散及可控氧化；（2）研究了GO调控水泥微观结构的效果及机理；（3）研究了GO化学结构、水泥基体微观结构及力学性能和耐久性的关系；（4）研究了水泥基复合材料中各组份之间的界面。.重要的研究结果：（1）获得了GO可控制备关键技术，制备出了适用于调控水泥水化产物及微观结构的GO纳米片层分散液；（2）发现了GO纳米片层可使水泥水化产物成为针状晶体、棒状晶体、花状晶体、多面体状晶体及构成规整微观结构的关键技术，提出了GO调控水泥基材料微观结构的机理；（3）获得GO的结构与水泥基体微观结构形貌、力学性能、耐久性能之间的关系；（4）证明了水化晶体之间其实是一种共生的关系，水化产物聚集体实际上是一种共生体，各个组份之间通过共生成为一个整体。.关键数据：（1）制备了厚度在5-10nm、长度在50-700纳米的GO片层分散液，可以进行插层、接枝共聚等改性；（2）通过调控GO纳米片层的尺寸和掺量，可以获得由针状晶体、棒状晶体、花状晶体或多面体状构成的规整微观结构，其抗压强度、抗折强度和拉伸强度提高100%以上，GO的掺量在0.01％~0.06%之间，GO用于水泥基复合材料的价格在每立方米水泥基材料10元－25元。.创新之处: 发现了GO纳米片层对于水泥基体微观和性能进行调控的方法和规律，提出了GO调控水化产物及结构的模板机理，发现了水化晶体通过共生、杂化、复合等方式得到规整微观形貌的机理。.科学意义：找到了实现水泥材料的微观结构及性能可控制备的方法，提出了可控制备的机理，对于实现水泥基材料的高性能、长寿命具有理论和技术的意义。