亲水/亚微级纤维诱导调控水泥浆体微结构形成机理研究

The primary defect, caused by the internal stress due to the different hydrating performance of cement components during the cementitious paste microstructure formation process, is the root problem of deterioration and poor durability of concrete. This project will study the internal stress distribution and crack driving force generating mechanism in cementitious paste microstructure forming process. On this basis, the cementitious paste microstructure formation is inducted and regulated by introducing hydrophilic/submicron fibers, the performance and size of which matched with cement hydration products, the growth model of cement hydration products and crack resistance mechanism is established, the growth behavior and its influencing factors of C-S-H on/along hydrophilic/submicron fibers surface will be researched, The submicron fiber for cementitious grouting mechanism of microstructure formation process of induction will be revealed, the mechanism of internal force in cementitious paste dispersed by submicron grade fiber will be discussed, the correlation model of submicron grade fiber reinforced cementitious paste microstructure and macroscopic properties will be established. Finally, the design theory and preparation methods of advanced cement-based composite, based on growth-induced and stress dispersion is proposed. This research for enriching and perfecting the design of high performance cement concrete preparation theory, improving overall performance, extending the life cycle of concrete, and reducing the cost of concrete, saving of resources and energy is important.

水泥基胶凝浆体在微结构形成过程中由于各组分水化性能差异而引起内力不均，进而产生的原生缺陷是引起水泥基复合材料损伤劣化及耐久性问题的根源。本项目拟依据细观力学原理分析研究水泥胶凝浆体微结构形成过程中内部应力分布特征和裂缝驱动力产生机制；在此基础上，通过引入性能、尺度与水化凝胶相匹配的亲水/亚微级纤维对胶凝浆体微结构进行诱导与调控，建立水化产物生长诱导模型及收缩阻滞机制，探明C-S-H凝胶在亲水/亚微级纤维表面的依附生长行为及影响因素，揭示亚微米级纤维对胶凝浆体微结构形成过程的诱导作用机理，探讨亚微级纤维对胶凝浆体内力的分散转移机制，建立亚微级纤维增韧水泥浆体微观结构与宏观性能的相关性模型，提出基于生长诱导和内力分散作用的水泥浆体设计方法。研究对于丰富和完善高性能水泥混凝土材料设计制备理论，提高混凝土的综合性能，延长混凝土生命周期，降低混凝土造价，节约资源能源具有重要意义。

本项目针对现代胶凝浆体由于各组分水化性能差异而产生裂缝、孔洞等原生缺陷，进而导致水泥基复合材料损伤劣化及耐久性下降等问题，研究了亲水性纤维的尺度对水泥胶凝浆体微结构形成过程的影响作用。采用H2SO4水解天然植物纤维制备不同尺度的纤维素纤维，天然纤维素纤维在酸解作用下逐步从母体上剥离成为直径从十几微米到几百纳米的纤维。探明了亚微米级亲水纤维对水泥水化产物C-S-H凝胶的生长诱导机理；纤维素纤维与水泥的良好相容性使水化产物依附于纤维素纤维表面生长；由于亚微级纤维素纤维在尺度上与水化产物C-S-H凝胶相匹配，随着表面水化产物的不断生长纤维逐渐被包埋其中，其诱导和桥接作用使独立的C-S-H凝胶簇连接融生成为体积较大的C-S-H凝胶聚集体，使胶凝浆体形成均匀致密微观结构，有助于提高水泥基复合材料的力学性能与耐久性。项目研究成果可为天然纤维素纤维的大规模资源化应用开辟新领域，也为提高水泥基复合材料基体性能提供技术途径。