It is shown that expansible ettringite forms in the topochemical reaction,and crystallizes in-situ on the surface of unhydrated aluminate minerals and orients radially.

发够产生膨胀的钙矾石是由局部化反应所生成；它们在未水化的铝酸盐物表面地结晶，呈放射状生长。

The expansion mechanism of hydroxide expanding phase for oil well cement slurry are discussed on the basis of principle of chemical thermodynamics and topochemical reaction model.

要基于膨胀剂地反应模型和化热力，讨论了晶体生长压的源动力及水泥浆体体积膨胀与结晶压的关系。