Abstract

The objective of this study is to prepare Al-F complex alkali-free accelerator from waste acid of titanium dioxide and to evaluate the hydration mechanism of F-ion complex. Setting time, stability, pH value, 1d compressive strength, 28d ratio of compressive strength and SEM were performed on cement pastes produced with an alkali-free accelerator (aluminum sulfate solution containing F-ion). Results showed that the addition of F-ion could form β -AlF₃•3H₂O complex, which improved the content of Al³⁺ ion and the stability of the system. The Al-F complex alkali-free accelerator contributed to the rapid formation of ettringite with network structure, as well as to a faster rate of cement dissolution and hydration. Moreover, a conceptual hydration model for pastes containing F-ion alkali-free accelerator was proposed. F-ion was beneficial to destroy the covering effect of C-H-S gel and form a continuous hydration. According to the results, variations in cement different setting time and mechanical strength caused by different concentration of F-ion in the alkali free accelerator are explained.

摘要

本研究的目的是利用二氧化钛废酸制备Al-F配合物无碱促进剂，并评价F-离子配合物的水合机理。对使用无碱促进剂（含氟离子的硫酸铝溶液）生产的水泥浆体进行凝结时间、稳定性、pH值、1d抗压强度、28d抗压强度比和扫描电镜观察。结果表明，F离子的加入可以形成β-AlF ₃ •3H ₂ O络合物，提高了Al ^{3+的含量。}离子和系统的稳定性。Al-F复合无碱促进剂促进了具有网状结构的钙矾石的快速形成，以及更快的水泥溶解和水化速率。此外，还提出了含氟离子无碱促进剂浆料的概念水化模型。F-离子有利于破坏CHS凝胶的覆盖作用，形成持续的水合作用。根据研究结果，解释了无碱促进剂中不同F离子浓度对水泥不同凝结时间和力学强度的影响。