【作者】 张宁；

【导师】 贺艳；

【作者基本信息】 广西大学 ， 化学工艺， 2020， 硕士

【摘要】 近年来,碱激发矿渣胶凝材料由于其低成本,对环境友好并且应用范围广,一直是学术界的研究热点。其物理与化学性质已被许多研究者研究,目前有研究发现矿渣组成复杂,不同产地矿渣的主要成分含量不尽相同并且导致其碱激发性能,耐久性能等性能存在应用上的差异,因此研究碱激发矿渣反应机理并提出普适性的应用规律是十分重要的。矿渣结构上的变化是影响其性能的一个主要因素。目前,大量的研究都专注于矿渣中硅铝含量的变化对其结构的影响,其他元素（如Mg,Ca）的影响受到了忽视,由于高炉矿渣中各元素组成及其含量无法固定,无法在改变钙镁含量的同时固定其它元素的比例,因此对于利用高炉矿渣研究钙镁含量变化对其结构影响是十分困难的。本文采用溶胶-凝胶法合成了化学计量可控的类矿渣粉体Al₂O₃-6Si O₂-y Mg O-x Ca O解决了这一问题,并研究了类矿渣粉体Al₂O₃-6Si O₂-y Mg O-x Ca O及其碱激发产物的相组成和性能,包括抗压强度和干燥收缩率。利用SEM/EDS表征了凝胶的微观结构,并采用XRD、FTIR、MAS NMR等手段对类矿渣粉体及其碱激发产物的结构进行了表征。结果表明,钙镁含量的变化会影响类矿渣粉体的玻璃相含量以及结构,类矿渣粉体中钙含量的增加会使其易生成方解石与托贝莫来石结构,类矿渣粉体中镁含量的增加还会使其形成石英以及氧化镁结构,过量的钙与镁均会降低前驱体的聚合度。当前驱体与水玻璃发生反应时,主要形成水化硅酸钙（C-S-H）与水化硅铝酸钙（C-A-S-H）的凝胶。值得注意的是当类矿渣粉体Al₂O₃-6Si O₂-y Mg O与水玻璃反应时会生成水化硅酸镁（M-S-H）,当钙源存在时,便不易形成该凝胶类型。此外,钙镁含量发生变化也会影响凝胶的结构,其中镁含量的增加会使碱激发产物中更易形成水化硅酸镁（M-S-H）以及水化硅铝酸钙（C-A-S-H）型凝胶结构,钙含量的增加会使凝胶更易被碳化形成方解石结构。水化硅酸镁（M-S-H）凝胶的平均链长明显小于水化硅酸钙（C-S-H）,因此镁含量的增加增大了碱激发类矿渣粉体的干燥收缩,而钙含量的增加会降低碱激发类矿渣粉体的干燥收缩。更多还原

【Abstract】 In recent years,alkali-activated slag cementitious materials have drawn attention of academic research due to their low cost,environment friendliness,and wide range of applications.The physical and chemical properties of alkali-activated materilais have been studied by many researchers.Furthermore,some studies have found that the composition of blast furnace slag is complex,the content of the main components of slag in different places is not the same,leading to the differences in application of alkali-activated slag cementitious materials,such as alkali excitation performance,durability performance,etc.Therefore,it is very necessary to study the reaction mechanism of alkali-activated slag and propose a universal application rule.The change of slag structural is one of the main factor that affects its performance.At present,a large amount of studies are focused on the influences of the change of silicon and aluminum content in the slag on its structure.The influence of the content of elements（such as Mg,Ca）has been ignored.As the composition and content of elements in blast furnace slag are uncertain,the ratio of other elements can not be fixed while changing the calcium and magnesium content,it is very difficult to use blast furnace slag to study the influence of calcium and magnesium content on its structure.Therefore,it is difficult to study the effect of calcium and magnesium content on the structure of blast furnace slag.In this work.The problem is solved by using a sol-gel method to synthesize stoichiometrically controlled precursors consisting of Al₂O₃-6Si O₂-y Mg O-x Ca O powders.The phase composition and performance of the Al₂O₃-6Si O₂-y Mg O-x Ca O powders and their alkali-activated products were investigated,including compressive strength and drying shrinkage.SEM and EDS are used to characterize the microstructure of the gel.The structure of simiulated-slag powders and their alkali-activated products were characterized by XRD,FTIR and MAS NMR characterizes.The results show that the change of the content of calcium and magnesium can affect the glass phase content and structure of the simiulated-slag powder.The increase of calcium content in simiulated-slag powder makes it easy to form calcite and tobermorite structures,the increase of magnesium content in simiulated-slag also makes it form quartz and magnesium oxide structure.High content of calcium and magnesium in simiulated-slag powders will reduce the polymerization degree of the precursors.When the precursors react with water glass,they mainly form gels of calcium silicate hydrate（C-S-H）or sodium silicate aluminate hydrate（C-A-S-H）.It should be noted that gel magnesium silicate hydrate（M-S-H）is formed when the simiulated-slag powder Al₂O₃-6Si O₂-y Mg O reacted with water glass,when calcium sources are present,the gel type is not easily formed.In addition,changes in calcium and magnesium content also affect the structure of the gel,The increase of magnesium content makes the gel structure of magnesium silicate hydrate（M-S-H）and calcium silicate hydrate（C-A-S-H）more easily to be formed in the alkali-activated products,and the increase of calcium content makes the gel more likely to be carbonized to form calcite structure.The average chain length of magnesium silicate hydrate（M-S-H）gel was significantly lower than that of calcium silicate hydrate（C-S-H）,so the increase of magnesium content increased the drying shrinkage of alkali-activated stimulated-slag powders,while the increase of calcium content decreased the drying shrinkage of alkali-activated stimulated-slag powders.更多还原