Influence of a thermal cycle at early age on the hydration of calcium sulphoaluminate cements with variable gypsum contents

详细信息    查看全文

• 作者：Sté ; phane Berger^a ; Cé ; line Cau Dit Coumes^a ; ^{celine.cau-dit-coumes@cea.fr} ; Patrick Le Bescop^b ; Denis Damidot^c ; ^d
• 关键词：Calcium sulphoaluminate cement (D) ; Hydration products (B) ; Temperature (A) ; Compressive strength (C) ; Stability (C)
• 刊名：Cement and Concrete Research
• 出版年：2011
• 出版时间：February 2011
• 年：2011
• 卷：41
• 期：2
• 页码：149-160
• 全文大小：2269 K

文摘

Hydration of a belite calcium sulphoaluminate cement was investigated over one year as a function of its initial gypsum content (variable from 0 to 35 % ). Particular attention was paid to the influence of the thermal history of the material at early age on its subsequent evolution. Pastes and mortars (w/c 0.55) were either cured at 20 °C or submitted for one week to a thermal treatment simulating the temperature rise (up to 85 °C) and fall occurring in drums of cemented radwastes. The thermal cycle accelerated the early stages of hydration and mainly decreased the proportion of AFt versus AFm hydrates, especially at low initial gypsum contents (≤ 20 % by weight of cement). It also strongly reduced the compressive strength of gypsum-free specimens (by 35 % after one year), and doubled their expansion under water. These results were explained by mineralogical evolutions towards a more stable phase assemblage which included retarded ettringite formation.