外部因素对钙矾石晶体结构及形貌的影响综述

钙矾石是硫铝酸盐水泥、通用硅酸盐水泥以及其他无熟料水泥等胶凝材料的重要水化产物之一,其晶体结构由中心柱和平行中心柱的沟槽组成。沟槽结构围绕中心柱呈六边形排列,硫酸根和水分子在沟槽中通过氢键网络将整个结构连接在一起。在水泥等胶凝材料的水化反应中,钙矾石晶体容易受到所处环境等外部因素的影响。其中反应物离子的过饱和度、温度、减水剂、氯离子、晶种等外部因素往往会改变钙矾石晶体结构中水分子和氢键的数量,进而改变晶体结构的稳定性及形貌等。此外,在合成钙矾石晶体过程中,搅拌桨型式及转速等也会影响钙矾石晶体结构和形貌,从而造成认知的不统一。本文在系统综述钙矾石晶体结构基础上,详细汇总了各种外部因素对钙矾石晶体结构和形貌的影响,同时介绍了各种研究手段,并对钙矾石晶体形成与形貌的研究方向提出了建议。

Review on Influences of External Factors on Crystal Structure and Morphology of Ettringite

Ettringite is one of the key hydration products of cementitious materials such as sulphoaluminate cement, common Portland cement and other clinker-free cement. Its crystal structure consists of a central column and grooves parallel to the central column. The hexagonal groove structure is around the central column and sulfate and water molecules connect in the grooves by a network of hydrogen bonds that keep the ettringite structure. In the hydration reaction of cementitious materials, ettringite crystals are easily affected by external factors. Among them, external factors such as supersaturation of reactant ions, temperature, water reducing agents, chloride ions and seed crystal often change the number of water molecules and hydrogen bonds of ettringite crystal structure, which in turn changes the stability of crystal structure as well as morphology. In addition, in the process of synthesizing ettringite crystal, the stirring paddle type and rotational speed also affect the crystal structure and morphology of ettringite, resulting in cognitive inconsistency. Based on a systematic review of the crystal structure of ettringite, the influences of various external factors on its structure and morphology in detail were summarized, various research methods were introduced, and some research suggestions on the crystal formation and morphology of ettringite were proposed.