碳纳米管水泥基复合材料的多尺度力学行为及其形成机理研究

Carbon nanotubes，especially multi-wall carbon nanotubes reinforeced composites, have become hotspots in the fields of cement based materials recently. Most of research work has shown that CNTs can improve the mechanical and microstructure performance of cement based materials when CNTs was highly dispersed in the matrix. Meanwhile, CNTs is a promising candidate for the multi-functional composite materials,such as thermoelectric conducting, electromagnetic shielding, piezoelectric,etc.However there is less research on carbon nanotubes reinforced cement based composites，More researches are badly needed to establish quantitative dispersion of carbon nanotubes within cement pastes and to carry out the influence mechanism of carbon nanotubes on microstructur. In this research,methods for dispersing cabon nanotubes and quantitatively dispersion determination within cement pastes will be investigated. Hydration products,anhydrated cement particles,ITZS and pore structure will be quantitatively characterized and analyzed by art-of-state testing technology on nano/micro scales,and the influence of carbon nanotubes on microstructure will be studied. The relation between microstructure and mechanical properties,such as.strength,toughness,wear resistance, elastic modulus,etc., of carbon nanotubes enhanced cement based composites will then be established.

目前，碳纳米管(CNTs), 特别是多壁碳纳米管(MWCNTs)增强复合材料是国际复合材料领域研究的热点。研究表明，碳纳米管能改善水泥基复合材料的力学和微结构性能，还可赋予水泥基复合材料导电导热、电磁屏蔽、压电等诸多新型功能性性能。然而，碳纳米管增强水泥基复合材料的研究相对较少，碳纳米管在水泥基材料中分散性的定量表征、碳纳米管对水泥基复合材料微结构的影响机理等方面的研究还不够深入。本项目将研究碳纳米管在水泥基材料中的有效分散技术并确定其分散性的定量表征方法，运用现代化的测试技术，在微纳米尺度上对水泥基复合材料中水化产物、未水化水泥颗粒、各层次界面、孔等微结构信息进行测试和定量表征， 提炼碳纳米管增强水泥基复合材料微结构形成机理。探讨碳纳米管增强水泥基复合材料强度、 韧性、耐磨性、弹性模量等宏观性能与微结构的有机联系，建立微结构与宏观性能的关系。

碳纳米管在对水泥基材料力学性能和微观结构的影响机理，是本领域的研究重点和难点。本项目通过透射电镜和扫描电镜实验分析了CNTs的分散性，确定了表面活性剂+硅灰+超声波分散的复合分散技术，提出了具有空间位阻效应的表面活性剂掺加浓度大于临界胶束浓度是实现CNTs在水泥基材料中实现良好分散的临界条件。提出了一种碳纳米管分散液中碳纳米管分散度R的定量计算方法。采用纳米压痕力学测试系统研究了碳纳米管对水泥基复合材料压痕硬度和压痕模量的影响，对压痕模量和压痕硬度的频率分布进行了Gaussian函数的解卷积分峰处理，从本质上揭示碳纳米管对水泥基复合材料的增强机制。通过实验研究、理论分析等多种研究手段，分析了碳纳米管对水泥基材料的力学性能和微观结构的作用机理，为碳纳米管增强水泥基材料的研究和应用提供了重要的学术意义和实用价值。