【作者】 王锦；

【导师】 李辉； 徐文；

【作者基本信息】 西安建筑科技大学 ， 资源循环科学与工程， 2015， 硕士

【摘要】 水化硅酸钙(C-S-H)是由水泥中的硅酸三钙和硅酸二钙水化生成的一种无定形物质,也是硅酸盐水泥的主要水化产物之一,其体积占水泥水化产物的三分之二,并且是水泥混凝土等水泥基材料强度的主要来源,水泥基材料的一些宏观特性(比如硬化、收缩、粘聚)都与水化硅酸钙有着密切的联系。但是由于水泥的水化产物种类多,单独从中提取水化硅酸钙进行单独的分析研究是不可能的,因此许多学者已尝试使用不同方法合成具有不同性质的水化硅酸钙,以及运用计算机的模拟方法对水化硅酸钙的微观结构进行研究与探索。本文首先分别以不同的钙硅比、温度以及时间应用水热合成法合成水化硅酸钙,并研究了不同的合成条件对水化硅酸钙物相、微观结构以及聚合度的影响。结果发现反应条件的改变会对生成的水化硅酸钙样品产生影响,以水热法合成水化硅酸钙时,钙硅比、温度及时间在一定范围内的升高可逐渐产生托贝莫来石、硬硅钙石和白钙镁沸石等不同矿物相,且所合成的水化硅酸钙样品表面从开始的密实状态逐渐变疏松,孔隙变大。由于水化硅酸钙结构主要以它的[SiO4]4-四面体阴离子的结合状态作为表征,当反应温度增加,Q1与Q2的峰均向高波数移动,其聚合度随温度的增加而提高。而随着钙硅比与反应时间的增加,均会造成水化硅酸钙聚合度的降低。其次由于水化硅酸钙结构复杂且种类多样化,本文应用计算机模拟的先进手段,根据Taylor假说,以Tobermorite结构为初始结构进行模拟,并讨论了模拟无定形态水化硅酸钙所适用的模块、晶胞大小与力学性能。在Material Studio软件中建立了11?Tobermorite结构的初始模型,并应用两个不同模块中的力场对初始结构进行优化,根据能量平衡、晶胞参数与力学性能的分析认为11?Tobermorite可以作为研究无定形水化硅酸钙结构的初始结构,两种模块中所选的力场对结构计算均具有理想的结果,且应用Forcite模块可以更快的使初始结构达到平衡状态。由于水化硅酸钙为无定形结构,本文采取了热处理工艺中的降温处理,通过计算机模拟此工艺最终得到无定形态的水化硅酸钙。更多还原

【Abstract】 Calcium silicate hydrate is an amorphous material which generated by hydration of C3 S and C2 S, and it is also one of the main hydration products of Portland cement,which accounts for two-thirds of the cement hydration products, and is a major source of reinforcement properties of cement, concrete and other cement-based materials.Besides, it is also the main source of some macro properties of cement-based materials,includinghardening, shrinkage, sticking. Due to various hydration products of cement, it is impossible to extract calcium silicate hydrate for analysis,, so many scholars have tried to use different methods to synthesis of calcium silicate hydrate and use computer simulation method to study and explore the microscopic structure of calcium silicate hydrates.This paper synthesizes calcium silicate hydrate based on different calcium silicon ratio, temperature and time, respectively by using hydrothermal synthesis method, and studied influence of different synthesis conditions on phase, microstructure and polymerization degree of the calcium silicate hydrate..Results showed that with increasing of calcium silicon ratio, temperature and time, different minerals such as tobermorite, xonotlite and Truscottite gradually occur, and the surface of synthesized calcium silicate hydrate tend to become compact.Calcium silicate hydrate mainly takes its [SiO4]4- combination state for characterization, with increasing of temperature,, the peak of Q1 and Q2 moved towards high wavenumbers, so the degree of polymerization increases with temperature. And with the increase of calcium silicon ratio and reaction time, can reduce calcium silicate hydrated polymerization degree.Because the complex structure and species diversity of calcium silicate hydrate, inthis paper, we applied advanced means of computer simulation to simulate tobermorite structure as initial structureaccording to Taylor hypothesis, and discussed the modules,cell size and mechanical properties applicable to the calcium silicate hydrate,We established 11 ?tobermorite structure as the initial model in Material Studio software,and applied the force field of two different modules to optimize the initial structure.According to the energy balance analysis, crystal cell parameters and mechanical properties, it is believed that 11 ?tobermorite can be used as the structure of the amorphous calcium silicate hydrate initial structure, and the selected force field in two modules both have ideal results, application of Forcite module can make the initial structure balance faster.Since calcium silicate hydrate is amorphous structure, annealing process of heat treatment process was applied for simulation and amorphous calcium silicate hydrate was obtained.更多还原