【作者】 芦令超；

【导师】 袁润章； 刘韩星；

【作者基本信息】 武汉理工大学 ， 材料学， 2005， 博士

【摘要】 传统硅酸盐水泥已经得到了广泛的应用,并且在二十一世纪仍然是最重要的建筑材料之一。但其具有的早期强度偏低,烧成温度高,硬化水泥浆体体积收缩等缺点不能适应现代建筑对高性能胶凝材料的要求,因此,如何提升水泥材料的性能,特别是早期力学性能、体积稳定和耐久性,并达到节约能源、节约资源、保护环境的目的,是水泥科技领域研究的重要方向,对国民经济与社会发展具有重要意义。通过矿物复合技术制备新型高性能水泥材料是解决这些问题的有效途径之一。 近年来,硫铝酸钡钙矿物的发现,引起了众多学者的关注。组成为2.75CaO-3Al₂0₃·1.25BASO₄（C₂.75B₁.25A₃ S）的硫铝酸钡钙具有优良的快硬早强性能,特别是其早期力学性能明显优于无水硫铝酸钙4CaO-3Al₂O₃.·CaSO₄（C₄A₃（?））,而且该矿物的烧成温度低,并在水化硬化过程中具有体积微膨胀等特性,能够有效的改善硅酸盐水泥的早期性能和耐久性,但是其后期强度增进率低。本文将硫铝酸钡钙矿物与硅酸盐熟料矿物体系进行复合,充分发挥硫铝酸钡钙和阿利特这两种高胶凝性矿物的优点,制备了早期性能优良的高胶凝性阿利特-硫铝酸钡钙水泥材料,系统研究了其制备工艺及组成、结构与性能的关系。 本文首先研究了C₂.75B₁.25A₃S的形成动力学、热分解特性和水化性能,结果表明:该矿物在1000"C左右就开始形成,1300-1350℃生成速度较快,继续升高温度到1370℃以上,开始发生缓慢分解,其热稳定性明显高于C₄A₃（?）;C2.75B₁.25A₃S矿物的水化速率较快,快硬早强性能突出;在1150～1300^C温度范围内C₂.75B₁.25A₃S的形成反应属于扩散动力学范围,满足Glinstling动力学方程F（a）=1-2 a/3一（1-a）²/3=K（T.c）t,矿物形成的扩散活化能为280.39kJ·mol（-1）。当合成温度为1350"C时,C₂.75B₁.25A₃S的形成同时受扩散和界面化学反应控制,满足界面化学反应方程F（a）=1-（1-a）^1/3=K（T.c）t;当少量CaF₂存在时, C₂.75B₁.25A₃S形成过程中一直伴随有C_llA₇’CaF₂的生成,当煅烧温度低于1300"C时,CaF₂能促进C₂.75B₁.25A₃（?）矿物的生成,高于1300^C时,由于C_llA₇·CaF₂的形成速度加快,CaF₂可能会延缓C₂.75B₁.25A₃（?）的形成。 采用正交实验的方法优选了熟料组成和煅烧制度,应用材料热力学的基本原理对熟料组成进一步优化,并综合考虑了水泥的力学性能和新型干法制造工艺对熟料组成设计的要求,确定了熟料最佳组成。在优化选择熟料组成的基础上,考虑到SO₃和BaO在熟料烧成过程中有少量挥发或固溶,使C₂.75B₁.25A₃S更多还原

【Abstract】 Traditional Portland cement has been widely used, and it is still one of the most important building materials in the 21st century. But it has some shortcomings, such as lower early strength, high sintering temperature and the bulk shrinkage of hardening paste etc., which can’t suit for the need of high-performance cementing material for modern construction. Therefore, how to improve the performance of cement, especially its early mechanics performance, bulk stabilization and endurance, saving energy sources and resource, protecting environment, are the main researching direction of science and technology of cement. It will take on important significance for country economy and social development. The technology of composite minerals is an availability approach for synthesizing a new high performance cement.In recent years, a mineral named barium calcium sulphoaluminate （3CaO3Al2O3-BaSO4） has been synthesized in laboratory successfully and many scientists are interested in the mineral performance. The barium calcium sulphoaluminate , whose composition is 2.75CaO3Al2O3-1.25BaSO4 （C₂.75B₁.25A₃S ）, has the optimal performance of rapid hardening and early strength. Its early mechanics performance is better than that of calcium sulphoaluminate（C4A3 s） which is the main mineral of sulphoaluminate cement . Furthermore, the sintering temperature of the mineral is lower and has tiny bulk expansion in the hydration process that can improve the early performance and endurance of Portland cement. In this paper, the mineral of barium calcium sulphoaluminate and the mineral system of Portland cement clinker were compound. The high cementing alite-barium calcium sulphoaluminate cement was obtained that has the main excellences both of alite and barium calcium sulphoaluminate minerals. The technology preparation, constituent, structure and performance of the cement were investigated carefully.First, the synthesis dynamics, decomposition and hydration behavior of C2.75B1.25A3 S were studied. The results show that the mineral start to be synthesized at about 1000℃, the producing rate is rapid at 1300-1350℃. When temperature is higher than 1370℃, C2.75B1.25A3S begins to be decomposed veryslowly. The hydrating rate of C2.75B1.25A3 5" is fast and it has excellent fast-hardening and early-strength performance. The kinetics of C2.75B1.25A3 S formation obey Glinstling formula F（a）=l-2a/3-（l-a）2/3=K{TC)t from 1150"C to 1300 °C, the diffusing activation energy of the mineral is 280.39kJmol’1. At 1350 *C, the kinetics of C2.75B1.25A3 S formation not only obeys Glinstling formula but also the equation of interface reaction F（a）=l-（l-a）1/3=K（TC）t. The presence of suitable amount of CaF2 can accelerate the formation of C2.75B1.25A3S when the sintering temperature is lower than 1300"C, but when the sintering temperature is higher man 1300"C, due to the formation of CnA7CaF2, the formation rate of C2.75B1.25A35 is retarded.Clinker constituent and burning technology were picked out and optimized by using orthogonal test method. The optimal mineral constituent of clinker is confirmed on the basis of mechanics performance, new dry process technology and theory count of material thermodynamics. At the base of the optimizing composition, excessive amount of SO3 and BaO was mixed into the clinker system to compensate SO3 and BaO volatilization or solid phase dissolution. The suitable addition of SO3, BaO and CaF2 in the clinker system was chosen out according to mechanics performance of cement. The results show that the alite and barium calcium sulphoaluminate minerals can compound and coexist in a clinker. It established the basic of alite - barium calcium sulphoaluminate cement. When the content of barium calcium sulphoaluminate is 6% and that of Portland clinker system with silica modulus 2.5, iron modulus 1.5 and KH 0.92 is 94%, the composite clinker has low Gibbs free energy and high reaction trend. In addition, mixed CaF2 can improve the reaction trend. Excessive SO3 and BaO in the clinker is benefit to the mechanics performance of cement, and the optimal excessive content of SO3 and BaO is 50% The suitable addtion of CaF2 is 0.6-1% and the sintering temperature is about 1380TI:. In the conditions of the optimal composition and preparing technology, the compressive strength of the alite-barium calcium sulphoaluminate cement is 27, 70 and 119MPa at Id, 3d and 28d curing age respectively, indicating excellent early strength and steady long-term strength.The influence of water/cement ratio, aluminium/sulfur ratio on the hydration rate, hydration degree, composition, microcosmic structure and porosity of hardened cement paste were researched by means of XRD, SEM-EDS, ESEM,DTA-TG and light microscopy, mercury intrusion porosimetry and hydration heat analysis. The results show that the hydration rate and early strength of the cement can be obviously improved with increasing gypsum and the optimal aluminium/sulfur ratio is 1/0.9. The hardened paste has dense structure and the most size of pores is smaller than lOnm.The hardened cement paste contains much more mineral AFt than that of Portland cement, which don’t make harmful pores decreasing with the increase of gel/space. It may be one of the reasons that the relation between the mechanics performance and the gel/space of the cement discord with f = Axn.Based on the work of laboratory, the product experiment obtained good effect. The results show that the compressive strength of alite-barium calcium sulphoaluminate cement is up to 28.1, 38.6 and 60.7MPa at Id, 3d and 28d respectively. The cement exhibits early-high strength, lower sintering temperature, about 1350°C and good grindability that can save energy sources. In addition, making the cement can use barium industrial residue that can save resource and protect environment.更多还原