イオン交換樹脂を含む懸濁水への難溶性無機化合物の溶解(第6報) : ポルトランドセメント

概要

論文の詳細を見る
Sparingly soluble inorganic salts such as BaSO_4 and CaC_2O_4・2H_2O are dissolved by soaking with an aqueous suspension containing a strongly acidic ion exchange resin, hydrogen form (H-R). The dissolution proceeds by the cation exchange reaction and can be traced by monitoring pH, specific conductivity(k, mS/cm) and ion(s) concentration(s) in the eluent. For the sake of simple operation; and for avoiding contamination by foreign ions, the dissolution method, different from the conventional method in which mineral acid is used, may offer a promising technique to elucidate the reaction mechanism including cement hydration The present work was undertaken to find a clue on the cement hydration chemistry and dealt with the dissolution process of portland cement powders. The dissolution was studied by batchwise addition of H-R to aqueous suspensions of cement with different degrees of hydration. Changes in pH and k during dissolution were compared for three kinds of cement, and analyzed quantitatively to discuss the dissolution based on the variations of dissolved amounts of constituent species for a rapid hardening cement (RHC) . The results obtained are summarized as follows ; (1) Dissolved Ca(OH)_2 is exchanged preferentially with H-R accompanying steep decrease in both k and Ca^<2+>. Sulfuric acid liberated from gypsum results in a predominant increase in k at the complete dissolution. (2) Changes in pH, k, Ca^<2+> (%) and SO_4^<2-> (%) are terminated by the addition of H-R of about ten times weight as much as cement powder used, then, a considerable solubility of molybdate reactive silicic(MRS) acid is observed. (3) Complete dissolution of unhydrated cement is confirmed by 100% dissolution of MRS acid, whereas the dissolution decreases with increasing degree of hydration. White silica gel precipitates for hydrated RHC (80℃, 72-280 h) after the complete dissolution, indicating that all of Ca in C-S-H gel is also adsorbed by H-R as cement minerals. (4) Equivalent ionic conductivity of the MRS acid is estimated as low as 3.6 S・cm^2/mol. The result indicates that the MRS acid does not contribute to the increase in k during the dissolution as mentioned in (1). (5) This method is a useful technique for monitoring hydration characteristics and chemical changes taking place during early hydration of cement.
社団法人日本セラミックス協会の論文
1990-11-01

イオン交換樹脂を含む懸濁水への難溶性無機化合物の溶解(第6報) : ポルトランドセメント

スポンサーリンク

概要

著者

関連論文

スポンサーリンク