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セメント系材料に対する硝酸塩等の影響評価II; 概要

The Effect of Nitrates on the Alteration of the Cementitious Material II

武井 明彦*; 大和田 仁*; 藤田 英樹*; 根岸 久美*

Takei, Akihiko*; Owada, Hitoshi*; Fujita, Hideki*; Negishi, Kumi*

セメント系材料に対する硝酸塩およびその変遷物質の影響を評価するため、1M NaNO3または1M NaNO3-0.5M NH3混合水溶液による液透過試験を実施した。pHが約12.5でポルトランダイトと平衡していると考えられる期間中、1M NaNO3の場合は、イオン交換水の場合に比べてCaの溶出が促進され、浸出液中のCa濃度は約1.5倍であった。NH3の影響は認められなかった。固相側のCa溶脱領域には、Naの濃集が認められた。

TRU waste includes various chemical compounds such as nitrates. The influence of the chemical compounds on the performance of the barrier system should be estimated. In this study, we estimated the influence of sodium nitrate and also that of the chemical compounds derived from the sodium nitrate to the degradation of the cementitious material. 1) Evaluation of the influence of nitrate ion on the alteration of the cementitious material Alteration of characteristics of cementitious material was evaluated by the water permeation test using sodium nitrate solution. The calcium concentration of sodium nitrate solution permeated sample was higher than that of blank. The result indicates that sodium nitrate solution will accelerate the alteration of cementitious material. the permeation test was continued by using the ion-exchanged water as the permeation-water. As the results, the chemical and physical characteristics of the samples approached to those of blanks.2) Evaluation of the influence of ammonia on the alteration of the cementitious material Alteration of characteristics of cementitious material in nitrate and ammonia solution was evaluated by the water permeation test using 1mol/liter-sodium-nitrate and 0.5mol/liter-ammonia solution (denoted as NH-solution in the following). The calcium concentration of NH-solution permeated sample was higher than that of blank and the value of the calcium concentration was almost the same as that of the sodium nitrate solution case. The alteration range by the calcium leaching of the solid phase of the NH-solution case shows similar trend to that of the sodium nitrate solution case. The acceleration of the calcium dissolution was considered from this result. And the change of the water-permeability indicated the same trend with sodium-nitrate-solution case. From these results we confirmed that ammonia solution would not influence the alteration of cementitious solution.

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