碱矿渣胶凝材料中激发剂与聚羧酸减水剂分子拓扑结构的耦合作用机理

The imcompatibility issues of polycarboxylate (PCE) superplasticiser with Alkali-activated slag (AAS)cement concrete not only cause the problems such as low fluidity and rapid slump loss of the fresh concrete, but also induce the durability problems, which hinders further engineering application of the AAS concrete. However, studies on the synergistic mechanism of PCEs with different molecular structures and activators has not been systematically reported, and the relationship between them has not been scientifically established as well. This project will be conducted from the perspectives of "topology - liquid phase - conformation", "topology - adsorption behavior - dispersion performance", "topology - microstructure - rheological properties", and the molecular structure parameters will be also induced to explore the coupling effect of the PCE and the activators. Moreover, the dynamic distribution behaviours, including adsorption, intercalation, coprecipitation process, and adsorption conformation of PCEs in strong ion strength environment were investigated. The mathematical models based on dispersion, adsorption and hydration were then established. The aim of this project is to provide theoretical support for optimising the performance of PCE, improve the compatibility of PCE with AAS, and provide the overall performance improvement of AAS concrete.

聚羧酸系高性能减水剂与碱矿渣混凝土相容性差，不仅引发新拌混凝土出现流动性低、坍落度损失快等问题，而且诱发耐久性问题，阻碍了碱矿渣混凝土的进一步工程应用。然而，有关不同分子结构的聚羧酸减水剂与激发剂协同作用机理的研究未见报道，聚羧酸减水剂与激发剂二元体系分子结构的匹配关系至今尚未建立。本项目从“拓扑结构-液相环境-分子构型”、“拓扑结构-吸附行为-分散性能”、“拓扑结构-微结构-流变性能”进行研究，同时引入分子结构信息参数，探讨聚羧酸与激发剂的分子耦合规律，明晰聚羧酸在强竞争吸附离子环境中动态分配行为（吸附、掩埋、共沉淀过程的影响）与吸附构象，建立基于分散、吸附、水化的数学模型，阐明聚羧酸对胶凝材料体系流变性能的影响规律。项目旨在优化聚羧酸减水剂性能和改善聚羧酸减水剂与碱矿渣相容性方面做出突破、为聚羧酸减水剂在碱矿渣混凝土中的应用提供科学依据和理论支持。

高效减水剂能够有效改善混凝土新拌性能，是混凝土必不可少的组分。但现有减水剂与低碳碱矿渣材料不相容，阻碍了碱矿渣的进一步工程应用。项目首先观察不同拓扑结构的减水剂（市售及合成）与碱矿渣的作用效果，研究不同掺加方法对其分散效果的影响规律，其次研究了激发剂与不同减水剂的相互作用机理，并研究了减水剂与其他外加剂的协同作用机理；并建立减水剂结构与碱矿渣微结构和流变性间的关联，最终研究聚羧酸减水剂分子结构对含泥地材以及不同辅助胶凝材料的相互作用机理，为碱矿渣的应用提供理论指导。主要结论如下：1）减水剂与高碱性激发剂发生化学反应导致锚固基团掉落，并且二者产生竞争吸附导致吸附量降低，进而降低分散效果；2）通过采用分开加的方式可以有效减少减水剂与激发剂的竞争吸附和化学反应，从而提升减水剂分散效果，并且改变碱矿渣材料的流变性能；3）木质素磺酸盐类减水剂与具有长侧链的聚羧酸减水剂对于碱矿渣材料工作性能的提升效果相对较好，具有长侧链和高电荷密度结构的PCE在高离子浓度溶液中分散效果较好；4）苹果酸等缓凝剂或者保坍型聚羧酸能够与聚羧酸减水剂协同作用，有效延缓碱矿渣凝结时间，提高碱矿渣材料的保坍性能。研究结果为开发碱激发矿渣胶凝材料用外加剂提供一定理论依据，促进碱矿渣材料的工业化应用。