环保型石膏-水泥-火山灰胶凝体系的早期水化过程研究

应用X射线衍射(X-ray diffraction,XRD)及热流仪研究了组分、水化环境对环保型石膏-水泥-火山灰胶凝体系(Gypsum-cement-pozzolan binder system,GCP)早期水化过程的影响。结果表明,胶凝体系水化后产物主要由钙矾石、生石膏、羟钙石、方解石以及非晶态CSH凝胶组成。随着水化龄期的延长,钙矾石的含量增加,而生石膏的含量减少。高效减水剂的掺入延缓了GCP胶凝体系的初期水化(0~70h)。在原料中加入偏高岭土可以促进钙矾石的生成;而加入硅微粉则会抑制钙矾石的生成。羟钙石仅可在水化开始后的第一周内测得,之后会由于火山灰反应而被消耗。水中养护促进钙矾石的生成,阻碍试样与二氧化碳的接触,使得方解石的含量大幅下降。

Study on Early Hydration Process of an Environmentally-friendly Gypsum-Cement-Pozzolan Binder System

The effect of composition and hydration condition of an environmentally-friendly gypsum-cement-pozzolan binder system (GCP binder system) on its early hydration process was studied by means of X-ray diffraction (XRD) and heat flow calorimeter. It was found that the main hydration products of the GCP-slurry after the early hydration were ettringite, gypsum, portlandite, calcite and amorphous CSH phase. The content of ettringtie increased over time whereas the content of gypsum decreased. Results from heat flow calorimeter indicated the retarding effect of superplasticizer on the hydration process within the first 70 h of GCP bin-dersystem. Metakaolin could improve the formation of ettringite whereas microsilica could hinder it. Portlandite could only be mea-sured within the first week after hydration due to the pozzolanic reaction. The underwater hydration condition could promote the formation of ettringite and prevent the contact between the sample and carbon dioxide as well, which could lead to the reduction of calcite content.