核磁共振技术用于塑性阶段水泥基材料中水分迁移相关行为的研究

水泥基材料的诸多性能与其内部结构息息相关，而初始结构（即塑性阶段结构），既直接影响塑性阶段工作性能，又作为起点影响水泥基材料性能发展。塑性阶段水分迁移直接影响着水泥基材料初始结构，进而导致塑性阶段性能及硬化后性能劣化。课题组前期研究发现核磁共振技术可对过渡区（模糊区域）水分的含量与状态进行准确表征，且横向弛豫分布与泌水的水泥浆体分层存在较好的对应关系，其为深入研究新拌水泥基材料内部的水分迁移提供了一种较好的方法。本课题拟通过核磁共振技术研究水泥基材料中水分迁移的特征，结合全自动真密度仪与孔隙水压力测试方法对水泥浆体沉降特征与水压力的关系，辅以结合脉冲场梯度核磁共振技术，对水泥基材料的水分渗透性等基础问题进行探究，以进行水分迁移的特征及内部结构的演化发展机制的理论和试验研究，重点研究水泥基材料的内泌水与外泌水的机制及调控措施，提高水泥基材料的质量稳定性，真正实现水泥基材料的高性能化。

The performance of the cement based materials directly correlates with the microstructure, and the initial structure(structure at plastic stage) influence the workability as well as the performance after hardening. Water migration occurs at plastic stage and its degree has an significant impacts on the initial structure which may lead to a low workability and weaken the performance of hardened material. We have found that the NMR technology can be utlized to obtain the information in the transition layer (fuzzy region), and distribution of transverse relaxation(T2) corresponds to the separated layers which evidenced that the NMR technology is suitable for the water migration study at plastic stage. This work will intensively investigate the water migration in the initial structure of cement based materials by using the NMR technology. Combining with the true volume and density measurement instrument and pore water pressure testing method, we will probe the relationship between the settling characteristics of cement particles and pore water pressure. Assisted with the pulsed-field gradient NMR, this study will investigate the penetrating properties of water molecules in the cement paste at plastic stage, and obtain the feature of water migration and the development of the inner structure of the cement paste. Especially, this work will focus on the mechanism study of external bleeding and inner bleeding in the cement based materials and relative adjustment measures to these phenomena. This study will contribute to improving the stability of the cement based materials, and it is beneficial for achieving the high performance of cement based materials.