Certain aspects related to the microstructural mechanisms involved in the expansion performance of cement pastes with ettringite based expansive agent have been analyzed. The possible microstructural mechanisms associated with the shrinkage observed after the maximum expansion is reached along with the influence of the porosity in the expansion obtained were evaluated in order to define the main microstructural mechanism involved in generating the expansion. Different microstructural techniques were considered, while the pore fluid composition evolution was similarly determined. The results obtained indicate that the shrinkage detected after the maximum expansion value should be related to the transformation of low crystalline ettringite in low crystalline monosulfate but the early formation of monocarboaluminate limits this conversion process. Moreover, the main mechanism involved in this expansion obtained is not the diffusion of constituent components from the expansive agent anhydrous grains and further ettringite precipitation, but rather the in-situ precipitation of these components with the subsequent ettringite formation.

已经分析了与钙矾石基膨胀剂水泥浆体膨胀性能所涉及的微观结构机制有关的某些方面。评估了在达到最大膨胀后观察到的与收缩相关的可能的微观结构机制，以及孔隙率对获得的膨胀的影响，以确定产生膨胀所涉及的主要微观结构机制。考虑了不同的微观结构技术，同时类似地确定了孔隙流体成分的演变。所得结果表明，在最大膨胀值之后检测到的收缩应该与低结晶单硫酸盐中低结晶钙矾石的转变有关，但单碳铝酸盐的早期形成限制了这一转变过程。