掺纳米颗粒水泥复合净浆的化学收缩与自收缩研究

With the development of nanotechnology, the nano-scale components have been introduced into cementitious materials. However, very limited study has been reported in the literature at home and abroad on a key issue, the chemical and autogenous shrinkages of cement-based composite paste with the addition of nanoparticles.Based on advanced tests and micro-analytical techniques, the present research is aimed at investigating into both chemical and autogenous shrinkages of nano-composite cement paste. There are three different types of nanoparticles chosen. The study includes: (1) research of the dispersion and filling of the nanoparticles in cement matrix, on which establishes the mathematical model for the accumulation state or micro-gradation dense packing of composite powder materials; (2) accurate measurements of both chemical and aotugenous shrinkages of nano-composite cement paste, to study the impact mechanisms of the nanopartices and the effects of other main factors on early-age volume change of cement paste, to analyze the correlation of the chemical and autgenous shrinkages; (3) modeling of the hydration kinetics of nano-composite cement paste in view of the mutual hydrations of various active components and their coupling factors, which drive, delay or restrict the hydration; (4)establishing and test verifying of the related mathematical models for the chemical and autogenous shrinkages of nano-composite cement paste based on the above micro-level models. The present research is of very much significance, providing the micro-level analysis for early-age shrinkage behaviors and engineering performances of cement-based materials with the addition of nanoparticles, and also the theoretical foundations and technical supports for further study and application of nano-composite concrete.

随着纳米科技的发展，胶凝材料引入纳米组分，而对掺纳米颗粒水泥复合净浆化学收缩与自收缩这一关键问题，国内外少见文献报道。项目基于先进试验方法和微观分析技术，选择三种不同类型纳米颗粒，开展掺纳米颗粒水泥复合净浆化学收缩与自收缩研究，包括：（1）水泥基体中纳米颗粒分散和填充状态研究，建立复合粉体堆积状态/微级配密实填充模型；（2）准确测量净浆化学收缩与自收缩，研究纳米颗粒对早期收缩的影响机理及其它影响因素；分析化学收缩与自收缩相关性；（3）建立掺纳米颗粒水泥净浆水化动力学模型，研究各组分交互水化效应，分析水化激励、延迟或制约的耦合因素；（4）基于复合粉体粒子堆积理论和水化动力学过程微细观层次模型，建立掺纳米颗粒水泥复合净浆化学收缩与自收缩相关数学模型，并试验验证。本项目为解释该材料早期收缩行为及工程性能奠定微细观层次的分析基础，为纳米复合混凝土的研究和应用奠定理论基础和提供技术支撑，意义重大。

胶凝材料组分在纳米尺度的延伸，其早期体积变形属关键性基础问题，现阶段研究甚少。掺纳米颗粒（主要为NS、NC、NT）水泥复合净浆化学收缩与自收缩研究，目的是揭示其早期收缩产生的机理及发展规律。研究内容和结论包括：.（1）分析了国内外化学收缩试验优缺点，研究ASTM C1608绝对体积法的缺陷，提出超薄弹性橡胶膜改良法；针对ASTM C1698波纹管法存在的问题，介绍提高波纹管法精度的措施。实践证明，改良试验操作简便、数据精度高，为项目奠定了坚实的试验基础，有助于推动相关试验的发展。.（2）掺纳米颗粒水泥复合净浆化学收缩与自收缩试验及影响因素的研究结果表明，纳米颗粒对早期收缩的影响是各种纳米效应综合作用的结果，与所掺纳米颗粒的种类、晶型、颗粒尺度、表面状态及掺量密切相关，其化学收缩与自收缩具有显著的一致性，为纳米颗粒对水泥基材料早期收缩行为影响机理、化学收缩与自收缩一致性理论分析及相关建模奠定了试验基础。.（3）基于自创试验，引入了三个参数：干态复合粉体形貌等级系数、等效堆积密度比及比表面积系数，建立了复合粉体堆积状态评价指标和方法，探索了复合粉体粒子堆积与填充状态，为从粒子堆积的角度理论研究和验证水泥复合净浆早期收缩机理及其变化规律奠定基础。.（4）掺纳米颗粒水泥复合净浆水化动力学研究，分析了纳米颗粒发挥的纳米效应及其与矿物掺合材等各组分之间水化激励、延迟或制约的耦合因素。相关研究结论、试验数据、图谱、图像、照片等，有助于充实相关研究，提供参考和借鉴。.（5）基于复合粉体堆积状态和水化动力学研究，建立了掺纳米颗粒水泥复合净浆化学收缩与自收缩相关数学模型，有助于填补相关研究空白，为解释该材料早期收缩行为及工程性能（如体积稳定性、抗裂性及耐久性等）奠定微细观层次的分析基础，为纳米复合混凝土的研究和应用奠定理论基础和提供技术支撑。.发表论文6篇，申请发明专利2项，依托项目培养毕业硕士研究生2名，1名在读硕士生选题与本项目有一定联系。参加国际、国内、行业学术会议10余人次。.