Carbonation of hydrothermally treated phosphate-bonded calcium aluminate cements

✍ Scribed by T. Sugama; N.R. Carciello

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 586 KB
• Volume: 22
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(92)90102-2

✦ Synopsis

To evaluate the potential of phosphate-bonded calcium aluminate cements (PBC) as wet C02-resistance cementitious materials in geothermal wells, specimens that had been autoclaved at 200"C or 300"C were exposed to Na2CO3-1aden water at 100"C or 200"C. The phase compositions of the hydrothermal reaction products formed in the autoclaved PBC consist mainly of hydroxyapatite (HOAp) and boehmite. The Na2CO3-induced carbonation of autoclaved PBC yielded two different carbonate species, CaCO 3 as the major species, and CO32"-incorporated HOAp as the minor one. The former species resulted from the carbonation of HOAp and free Ca dissociated from the calcium aluminate reactants; the latter was derived from the substitution of CO32" for OH" in HOAp. However, the rate of CaCO3-related carbonation was very small, suggesting that the PBC can be categorized as a CO2-resistant cement.