A reply to S. Chatterji's discussion on “tricalcium aluminate hydration in the presence of lime gypsum or sodium sulfate”

✍ Scribed by Mario Collepardi; Giorgio Baldini; Marco Pauri; Mario Corradi

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 160 KB
• Volume: 9
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(79)90056-5

✦ Synopsis

The authors are very grateful to Chatterji as his remarks provide a welcome opportunity to clarify some points of our paper.

According to Chatterji's, in the C3A-gyps~m-water system, we would have attributed "the first part of the second high activity period to ettringite formation." Moreover, Chatterji says that "the onset of the second high activity period, after a delay of about 2 hours, seems to have been attributed to sorption of water by the initially formed ettringite crystals." Really, we have attributed the "second high activity period" ("double peak") neither to ettringire formation nor to water sorption. Indeed, we have written (p. 577) that "This double peak can be ascribed to the conversion of ettringite into monosulfate because of the consumption of gypsum (Fig. 2C)". We have also concluded (p. 579) that "After some hours ettringite coating C3A grains is converted to monosulfate because of the consumption of gypsum and C3A hydration is renewed."

As far as the three questions of Chatterji are concerned, we give the following answers: