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.

发现能够产生胀的钙矾石是由局部应所生成；它们在未水的铝酸盐物表面原地结晶，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.

要胀剂原地应模型和热力原理，讨论了晶体生长压的源动力及水泥浆体体积胀与结晶压的关系。