A reply to a discussion by S. Chatterji of the paper “interaction of chloride and C-S-H”

✍ Scribed by J.J. Beaudoin; V.S. Ramachandran; R.F. Feldman

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 64 KB
• Volume: 21
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(91)90121-w

✦ Synopsis

The authors thank Dr. Chatterji for his interest and comments. We are pleased to be able to confirm his personal speculation pertaining to 'tightly-held' chloride.

Chloride extraction with a calcium hydroxide saturated calcium nitrate solution, 0.1 N NaOH solution or calcium hydroxide suspension has not been attempted by the authors. Removal of 'tightly-held' chloride by these methods would have to be confirmed by experiment. Calcium chloride may interact with Ca(OH) 2. It is known that in the system CaO-CaC12-H20, calcium oxychlorides may form if the concentration of CaC12 is about 18%.(1)

The authors agree that the structural implications of a variable C/S ratio product are different from that of a fixed C/S ratio. Results from the wide range of C/S ratio products in the study support this view. The recent growth of by-product concrete, e.g. silica fume is relevant in this context. In hydrating cement systems, dimer is formed initially and is later supplemented and replaced by larger species. The nature of the reactants affects the process, e.g. by-product slica.