Early hydration of quick cements in the system C11A7 · CaF2C2SC2(A,F)

✍ Scribed by D. Knöfel; J.-F. Wang

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 566 KB
• Volume: 1
• Category: Article
• ISSN: 1065-7355
• DOI: 10.1016/1065-7355(93)90012-d

✦ Synopsis

To explain the initial hydration of quick cements of the system CllA7 • CaF2-C2S-Ct(A,F), their S03/Al203 ratio was varied, Portland cement was added to increase the alcalinity of the pore solution in the cement stone, and setting retarder was used during the tests. The process of hydration was investigated with the help of X-ray diffraction and scanning electron microscopy as well as via the determination of the chemically bound water. The quantity of rapidly growing ettringite crystals increases with a rising S03/ AI203 value. The optimal S03/A1203 value of the system CllA7 • CaF2-C2S-C2(A,F) is found between 0.26 and 0.38. The sole addition of setting retarder or Portland cement can distinctly reduce the formation of monocarbonate or even stop it completely. However, the simultaneous addition of both additives (setting retarder and a Portland cement) supports the formation of ettringite and monocarbonate crystals and through this also supports the increase of initial strength of quick cement.