The Influence of Sodium Hexametaphosphate (Na₆P₆O₁₈) on Hydration of Calcium Aluminate Cement Under Hydrothermal Condition

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• 作者：Martin Palou^a ; ^b ; ^{martin.palou@savba.sk" class="auth_mail" title="E-mail the corresponding author} ; Eva Kuzielová ; ^a ; ^b ; Matú ; &scaron ; Žemlička^a ; ^b ; Vladimí ; r Živica^a
• 关键词：Hydrothermal curing ; hydroxyapatite ; Alumina cement ; acid-base reaction
• 刊名：Procedia Engineering
• 出版年：2016
• 出版时间：2016
• 年：2016
• 卷：151
• 期：Complete
• 页码：119-126
• 全文大小：1583 K

文摘

The hydration of High alumina Cement (HAC) in the presence of sodium polyphosphate (sodium hexametaphosphate -Na₆P₆O₁₈) was investigated under normal and hydrothermal condition. Reference sample and modified one were submitted to long-term hydration (365 days). It was found out that sodium hexametaphosphate has increased the compressive strength. The main hydration products of HAC (C₃AH₆ and gibbsite) were found stable over time. However, when submitted to hydrothermal curing conditions of 20 bars (corresponding to 220 °C) during 7 days, binder has lower compressive strength values, but increasing with time. Thermal analysis method, X-ray diffraction and Scanning electronic microscopy were used to characterize the reaction products. Under hydrothermal curing (220 °C/ 20 bars), the main hydration products were hydroxyapatite (Ca₅(PO₄)₃OH) and nordstrandite (A(OH)₃), known as chemically bond ceramics formed by acid-base reaction between HAC and sodium hexametaphosphate.