基于超轻集料的碱激发水泥基多孔材料的制备及其热传导机制

Porous cement-based material has been widely used in existing wall insulation materials. But this kind of material has a common drawback: the higher porosity will result in the sharply fell of its mechanics performance and severe shrinkage and cracking. Aiming at this problem, Alkali-activated porous cement-based wall insulation material (APCM) has been designed. Porous matrix with high strength and high durability was formed through alkali-activated reaction, silicate hydrothermal reaction and gas formation reaction. While the enhanced strength, the heat resistance and the volume stability was obtained by the addition of functional components. .The design principle of the APCM will be put forward on the basis of the study of the influence of alkali-activated agent, W/B ratio, aggregate, binder system and etc, on the hydration products and its performance. The microstructure of APCM is studied by XRD、SEM and EDXA..The composition characteristics of APCM hydration products are studied, and the quantitative analysis of its composition was put forward. The mix proportion parameters were adjusted by changing the dosage of sodium silicate, fly ash, metakaolin, lime, cement, and foam stabilizer. The influences of every component on the hydration product composition, gas generating effect and performances of APCM were also found out. On the whole, the study provides important references for the preparation of APCM..The surface functionalization treatment technology of sludge lightweight aggregate is studied, and the technology can not only improve the structure of interface region between aggregate and matrix, also can solve the floating problem of the super-lightweight aggregate, and the density matching principle between slurry and aggregate. The effects of volume dosage and cylinder compressive strength of sludge lightweight aggregate were studied as well, and it is of great important for the application of sludge lightweight aggregate in APCM..A pore representation method based on image processing technology will be developed using MATLAB. The heat conduction process will be simulated and analyzed by ANSYS. Moreover, a mathematical model between pore structure and thermal conductivity will be established.

建筑保温材料的保温、力学和耐久性能的匹配是实现建筑节能的关键。本项目针对多孔水泥基建筑保温材料在低导热系数条件下强度低，耐久性差的问题，设计一种碱激发多孔水泥基保温材料(简称APCM)，利用碱激发反应、硅酸盐水热反应与发气变化形成多孔高强高耐久基体，并在基体中内置污泥超轻陶粒，实现增强、阻热、体积增稳的强化作用。研究碱激发反应原理与作用机理，分析激发剂、发泡剂、集料、胶凝体系、外加剂等对水化产物和性能的影响，提出APCM设计原理和方法；通过现代测试方法对APCM的微结构进行多尺度研究，揭示其组成与微结构形成机理；研究APCM水化产物组成特点，探明各主要组分对其水化产物组成、发气效果和性能的影响规律；制备轻质、具有一定强度、优良的保温性能及耐久性能的多孔水泥基材料，利用ANSYS和MATLAB等软件对APCM进行能耗仿真分析，建立孔结构与导热系数模型，探明APCM在服役环境下的劣化机理。

本项目设计了一种碱激发多孔水泥基墙体保温材料（Alkali-activated porous cement-based wall insulation materials，简称APCM），它利用碱激发反应、硅酸盐水热反应与发气反应形成多孔高强高耐久基体，并在基体中内置功能组分，实现增强、阻热、保持体积稳定的强化作用。该多孔材料能够较好地兼顾保温性能与力学性能、耐久性能，它的开发对多孔水泥基墙体保温材料应用领域的拓展具有重要意义。.在深入研究水泥基复合材料特点的基础上，提出了APCM的设计原理：胶凝材料组成基于碱激发效应和硅酸盐材料水热反应，多孔结构由铝粉与碱反应形成，功能组分设计依据集料增强及界面增强技术。在此基础上，提出了APCM的设计方法：采用钠水玻璃作为碱激发剂，粉煤灰和偏高岭土作为硅质材料和碱激发胶凝材料，石灰和水泥作为钙质材料和碱性材料，铝粉作为发气剂，超轻集料作为功能组分。通过XRD、SEM、EDXA等测试方法对APCM的组成成分和微观形貌进行研究，验证了设计的可行性，并探明了APCM微观结构特点：托勃莫来石和C-S-H（I）相互交织构成凝胶网络，生成的水石榴子石填充在凝胶网络中，沸石类矿物聚集在凝胶网络表面。.研究了APCM水化产物组成特点，提出了其组成成分定量分析方法；通过调整钠水玻璃、粉煤灰、偏高岭土、石灰、水泥及稳泡剂的配合比参数，探明了各组分对APCM水化产物组成、发气效果和性能的影响规律，为制备APCM基体提供了重要的参考依据。.研究了轻集料制备技术，通过对污泥化学成分的分析，确定了原料组成设计；通过对污泥TG和DSC分析，掌握污泥焙烧过程特点，依据该特点确定了污泥轻集料预烧制度；通过研究增强组分、焙烧时间和焙烧温度对集料性能的影响，提出了超轻污泥集料制备方法。研究了污泥超轻集料的体积掺量和筒压强度对集料与浆体匹配性的影响，它对污泥超轻集料应用于APCM具有重要的指导意义。.针对APCM孔特性，采用MATLAB开发了基于图像处理技术的孔表征方法；研究了孔特性的计算机识别技术，掌握了反映孔特性图像的栅格形式转化为矢量形式的方法；通过ANSYS模拟不同孔特性的APCM在热传导中温度场的变化，探明孔结构对热传导过程的影响规律，直观的反映了孔形状对热传导的影响；采用分形理论对孔形状进行表征，建立孔结构与导热系数的数学模型，应用于APCM导热系数预测。