碳酸钙-铝酸盐矿物水化行为与胶凝性能研究

The limestone powder with calcium carbonate as its principal constituent composition is often used as the addition of cement or mineral admixture of concrete. Sometimes limestone powder is applied to modify the Performance of aluminate cement. Calcium carbonate can react with C3A in Portland cement or aluminate cement clink to form monocarboaluminate. The study on hydration behavior of CaCO3-aluminates composite system is not enough systemic, the cementing properties of this system is not even mentioned, and its application value is worthy to research. The problem that the concrete with the addition of limestone powder can be easily damaged due to the thaumasite form of sulfate attack (TSA) also needs to be solved urgently. This project is to use the synthetic aluminate minerals and aluminate cement, choose the different calcium carbonate, and adjust the fineness and proportion of materials. The CaCO3-aluminates composite system will be taken as research object. The hydration heat, the composition of hydrates, as well as the hydration kinetics and thermodynamics under the different influencing factor will be analyzed. The cementing properties of this system will be tested, including the setting time, mechanical property, volume deformation and etc. The structure and properties of calcium aluminate carbonates will be investigated, and the application value of the monocarboaluminate will be explored further. The correlation between the participation of calcium carbonate in the formation of Thaumasite and the reaction of calcium carbonate with aluminates will be analyzed and compared under the sulfate environment at low temperature, and the control technique of CaCO3-aluminates hydration will be discussed in order to find a way for the solution of concrete damage due to TSA.

以碳酸钙为主要成分的石灰石粉常被用作水泥混合材及混凝土掺合料，或用于铝酸盐水泥改性。碳酸钙可与硅酸盐水泥中C3A，也可与铝酸盐水泥熟料反应生成水化碳铝酸钙。国内外对碳酸钙-铝酸盐矿物复合体系水化行为研究不够系统，其胶凝性能甚少涉及，有无实用性值得探讨；石灰石粉掺入混凝土后极易发生TSA破坏的问题也亟待解决。拟采用人工合成铝酸盐矿物、铝酸盐水泥，选择不同碳酸钙物质，调整物料细度、比例等，以碳酸钙-铝酸盐矿物复合体系为对象，分析其在不同影响因素下的水化放热、水化产物组成结构、水化动力学与热力学，测试复合体系的胶凝性能，包括凝结时间、力学性能与体积稳定性等，分析水化碳铝酸钙的结构与性能特点，探究其应用价值；在低温硫酸盐侵蚀环境下，分析比较碳酸钙参与Thaumasite型腐蚀反应，和参与铝酸盐矿物水化反应的相关性，探讨碳酸钙-铝酸盐矿物水化反应调控技术，以期找到解决混凝土TSA破坏问题的技术途径。

碳酸钙可与铝酸盐矿物反应生成水化碳铝酸钙，然而国内外对碳酸钙-铝酸盐矿物复合体系的水化行为研究不够系统，其胶凝性能甚少涉及，有无实用性值得探讨。基于此原因，本项目探究了碳酸钙与铝酸盐矿物在不同掺比、不同铝酸盐矿物种类以及碳酸钙形态条件下的水化放热、水化产物组成与结构、水化动力学以及胶凝性能等，得到以下试验结果：.①碳酸钙能够促进铝酸盐矿物的水化，针对高C/A、低活性铝酸盐矿物的效果更明显。由碳酸钙反应放热量分析表明，相较于铝酸盐水泥熟料，C12A7与碳酸钙的反应程度更高，因此选用高活性铝酸盐矿物更有利于激发碳酸钙的反应活性。.②碳酸钙与铝酸盐矿物之间反应显著，当碳酸钙与铝酸盐水泥熟料、C12A7的掺比分别为1:9、3:7时水化碳铝酸钙（单碳）生成量达到最高。相较轻钙和重钙，掺加纳米碳酸钙不会进一步促进水化碳铝酸钙的生成。同时注意到，碳酸钙与铝酸盐水泥熟料复合后水化后期疑似生成三碳，单碳随着期龄增加将发生分解。由SEM分析可知，单碳为不规则类六方形薄片状，碳酸钙-C12A7复合体系中单碳晶体生长程度更高。.③采用Krstulović-Dabić水化动力学模型对碳酸钙-铝酸盐矿物体系水化反应的结晶成核与晶体生长（NG）、相边界反应（I）及扩散过程（D）等过程进行了表征。分析结果表明，碳酸钙能够提高NG过程的反应速率，当W/B为1.0时，铝酸盐水泥熟料、C12A7掺加50%轻钙粉后NG过程的反应速率常数KN由0.2413、0.1064分别增加到0.2989、0.1880。铝酸盐水泥熟料掺加碳酸钙后NG、I过程相应减弱和增强，而D过程基本保持不变。C12A7掺加碳酸钙后NG、I过程均减弱，D过程增强。.④掺入过多碳酸钙会对工作性产生不利的影响。碳酸钙对铝酸盐水泥熟料、C12A7分别起到了促凝和缓凝效果。相较于铝酸盐水泥，C12A7掺加碳酸钙后力学性能显著提高。.研究表明，碳酸钙-铝酸盐矿物复合体系水化反应显著，反应产物具有良好的胶凝性能，以碳酸钙与铝酸盐矿物为原料，有望制成一种以水化碳铝酸钙为主要产物的新型水泥体系。