高负电荷密度矿物与高效减水剂在碱矿渣水泥中的协同作用机理研究

Alkali-activated slag cement (AASC), which is a clinker-free, green and low carbon binder significantly differing from traditional Portland cement, meets the requirement of energy saving and omission reducing strategy. The widely application of AASC is restricted by the high viscosity, however, traditional superplasticizers lose efficacy or has very low work efficiency in AASC system, which become one of the technical obstacles. To solve this challenge, one of the most significant ways is to find superplasticizer which is suitable for AASC. This project was based on mineral flotation and DLVO theory. Starting with the research on the mechanism of synergistic effect of negatively charged mineral admixtures and superplasticizer. Study on the surface-charge chemistry of slag under the influence OH-, Na+ and superplasticizer, establish the charge distribution model of slag. From the electrostatic repulsion and internal energy points of view, the negatively charged mineral admixture is introduced into AASC, study on the synergistic effect of superplasticizer and minerals on the surface chemistry with the changes of electric density and the regulation of the functional groups, to reveal the mechanism of adsorption and dispersion behavior of superplasticizer in AASC,. The rheology properties, hydration process, mechanical properties and microstructure of AASC will be investigated. The outputs will be useful and helpful to improve the practical application of AASC in our country and master the core technology in this field.

碱矿渣水泥是一种绿色高性能胶凝材料，其开发利用符合我国节能减排发展战略。碱矿渣水泥浆体粘度大，传统减水剂在该体系失效或作用效率极低，是制约其应用发展的主要障碍之一，深入研究碱矿渣水泥系统的塑化机理是解决上述问题的核心基础。本项目以矿物浮选理论与DLVO理论为基础，系统研究高负电荷密度矿物与高效减水剂在碱矿渣水泥中的协同作用机理。研究矿渣表面荷电行为以及OH-、Na+与高效减水剂在其表面吸附规律，建立碱溶液中矿渣表面空间荷电模型；通过向碱矿渣水泥引入高负电荷密度矿物的技术途径，增加体系颗粒之间的静电斥力和内能，研究矿物电荷密度、官能团对碱矿渣水泥表面化学特性的影响规律，揭示高负电荷密度矿物与高效减水剂在碱矿渣水泥体系的协同作用机理；研究高负电荷密度矿物与高效减水剂对碱矿渣水泥浆体流变性能、水化过程、硬化体力学性能及微观结构的影响。研究成果将为碱矿渣水泥塑化剂开发和应用提供理论基础与技术支撑。

碱矿渣水泥是一种具有优良力学性能、抗冻性能和抗化学侵蚀性能的新型胶凝材料，其开发应用符合经济社会可持续发展方向，具有良好的应用前景。碱矿渣水泥浆体的粘度较大，传统的减水剂在该体系中作用效率极低甚至失效是制约其应用发展的关键技术问题之一，深入开展碱矿渣水泥浆体塑化性能研究是解决上述问题的核心基础。因此，研究碱矿渣水泥浆体塑化性能，揭示碱矿渣水泥浆体流变行为机制并提出相应的改善措施对提高碱矿渣水泥浆体工作性和拓展碱矿渣水泥高效应用具有重要意义。.针对碱矿渣水泥浆体粘度较大的主要问题，本项目研究了碱组分对碱矿渣水泥浆体流变性的影响，采用电泳法、薄层渗透法、接触角法及旋转摩擦法等分析了碱矿渣水泥浆体中矿渣表面荷电特征，研究了颗粒间静电斥力、范德华引力、路易斯酸碱作用力及摩擦作用对浆体流变性的影响，揭示了碱矿渣水泥浆体的流变机理。在此基础上，通过。采用FTIR、XRD和TEM等测试方法分析了表面活性剂在碱组分溶液中的分子结构稳定性及形貌特征，并结合表面活性剂在碱组分溶液中的扩散情况，分析了表面活性剂效率降低的原因，提出了高负电矿物协同萘系减水剂改善碱矿渣水泥浆体流变性，并研究了高负电矿物协同萘系减水剂对碱矿渣水泥水化放热、力学性能及微观结构的影响，为改善碱矿渣水泥混凝土工作性，促进碱矿渣水泥高效应用提供了新的技术途径。