适应大温差环境的硫铝酸盐基复合胶凝材料组成、性能及其机理研究

Sulfoaluminate-based composite cementitious materials can be utilized to prepare high performance cementitious materials due to its rapid hardening, high early strength and shrinkage compensation. However, one of the main hydration products, ettringite tends to transform to AFm under high temperature, and thereby cause a deterioration of the microstructure and exert an adverse effect on the constructions. In this work, the influence of variation in environmental temperature (0-60℃) on the solubility and dissolution rate of sulfate and aluminate phase will be studied in the corresponding pure minerals. The variation of contents, morphology, positions and transformation levels of ettringite with the temperature will be determined by using different types and amount of gypsum, modifying the ratio between sulfate minerals and alumina minerals. The effect of temperature on the formation and transformation of ettringite will be analyzed from a thermodynamic point of view. Meanwhile, the influence of temperature on the ions concentration of pore solution, mineralogy compositions and pore structure will be studied. The relation between the hydration process and the temperature will be determined. Based on the abovementioned experiments, a numerical model with respect to the development of microstructure, physical properties and raw materials compositions will be established. The theory and technology related to the composition design and performance modification of sulfoaluminate-based composite cementitious materials under various temperatures will be proposed. This study is of great theoretical contribution and application guide for the development of cementitious materials which can be applied in the region with significant temperature variation.

硫铝酸盐基胶凝材料因出众的快硬、早强及收缩补偿性能，可制备高性能水泥基材料，但因其主要水化产物钙矾石在高温下易发生物相转变，导致微结构破坏，对工程质量产生不利影响。本项目在系统研究不同环境温度下(0-60℃)硫铝酸盐基复合胶凝材料主要硫质及铝质单矿物溶解度及溶解速率的基础上，通过掺加不同种类及含量石膏，调整原料中硫质及铝质的匹配方式及比例，考察浆体中钙矾石生成量、位置及转变程度等随温度的变化规律，从热动力学角度揭示温度对钙矾石生成及转变的影响；同步研究温度变化对体系中孔溶液离子浓度、物相组成、孔结构的影响，弄清水化过程与温度的关系；构建不同温度及温度变化条件下复合胶凝材料物理力学性能与微结构演变及原料组成、性质间相互关系的数值模型，最终提出适应大温差环境的硫铝酸盐基复合胶凝材料微结构调控理论和技术。本课题对开发可适用于不同建筑气候区或大温差环境的胶凝材料具有重要理论指导意义和实际应用价值。

硫铝酸盐基复合胶凝材料因出众的快硬、早强及收缩补偿性能，已广泛用于制备水泥灌浆、自流平砂浆等高性能水泥基材料。综合考虑该类材料主要水化产物钙矾石（AFt）高温下易发生物相转变，项目在探明不同温度下(0~80℃)硫铝酸盐水泥自身水化特性的基础上，通过调整原料中硫质、铝质及硅质的匹配方式及比例，系统考察硫铝酸盐基胶凝材料物理力学性能、水化进程、孔结构及微结构演变等水化特性的温度敏感性。研究表明，养护温度和石膏均能显著影响硫铝酸盐水泥的水化。养护温度越高，水泥熟料及石膏等原材料的溶解越快，水化早期AFt、铝胶等水化产物生成速度越快，使得孔结构越致密、早期水化程度及强度越高；但越易生成单硫型水化硫铝酸钙（AFm），水化后期微结构发展越不均匀，水化程度越低，抗压强度甚至倒缩。与无水石膏相似，脱硫石膏的掺入加速了硫铝酸盐水泥熟料的凝结，抑制了AFt向AFm转变，显著降低28 d内的干燥收缩，还能有效提升熟料在高温下的抗压强度，完全可替代天然无水石膏配制出更优良的硫铝酸盐水泥，具有广阔的应用前景（尤其适合高温条件）和社会环境价值。而大量硅酸盐水泥的掺入，大幅提升了孔溶液中硅酸根的浓度，使水化产物以片状水化钙铝黄长石为主，硬化浆体力学强度显著降低。项目最终构建出不同温度下硫铝酸盐基复合胶凝材料物理力学性能与微结构演变及原料组成、性质间相互关系的数值模型；并以硫铝酸盐基自流平砂浆的90 d内水化为抓点，系统验证所得成果与实际工程应用的相关性。项目的开展丰富了适应大温差环境的硫铝酸盐基复合胶凝材料的微结构调控理论和技术，具有重要的理论意义和实际应用价值。