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Journal Articles

Development of phosphate modified CAC cementitious systems with reduced water content for the immobilization of radioactive wastes

Garcia-Lodeiro, I.*; Irisawa, Keita; Meguro, Yoshihiro; Kinoshita, Hajime*

Proceedings of 15th International Congress on the Chemistry of Cement (ICCC 2019) (Internet), 10 Pages, 2019/09

The immobilization of low or intermediate-level radioactive wastes in cements is a common practise. Grout, a mixture of Portland cement and supplemental cementitious materials, is commonly used to encapsulate the wastes. However, the conventional cementing process based on portland cement has the risk of hydrogen gas generation, due to the radiolysis of the water intrinsically present in the cement matrix both in the pore solution and the hydrated products. The addition of phosphates to calcium aluminate cement (CAC) is interesting because this system sets and hardens via the acid-based reaction, between the acid phosphate solution and the basic CAC cement. Due to this different mechanism of reaction, it would be possible to generate a solid cementitious product with a reduced water content, which can be beneficial to minimize the risk of hydrogen gas generation associated with the radiolysis of water by radioactive wastes. The present study investigates the effect of water reduction on a phosphate modified CAC systems at different temperatures (35$$^{circ}$$C, 60$$^{circ}$$C, 95$$^{circ}$$C, 110$$^{circ}$$C,180$$^{circ}$$C) in the initial 7 days of curing. Experimental results indicate that these phosphate-based cements do not form the conventional CAC crystalline hydration products in the condition tested, but provide a structural integrity despite a significant amount of water loss. The results also suggest the formation of hydroxyapatite in samples cured at 95$$^{circ}$$C.

Journal Articles

P and S K-edge XANES of transition-metal phosphates and sulfates

*; Nagoshi, Masayasu*; Noro, Hisato*; Baba, Yuji; Yamamoto, Hiroyuki; Sasaki, Teikichi

Journal of Electron Spectroscopy and Related Phenomena, 101-103, p.607 - 610, 1999/00

 Times Cited Count:59 Percentile:91.72(Spectroscopy)

no abstracts in English

Journal Articles

Infrared-absorption studies on some organic phosphates

Applied Spectroscopy, 21(5), p.332 - 335, 1967/00

no abstracts in English

Oral presentation

Effect of phosphate modification on incorporation of caesium nitrate by calcium aluminate cement

Irisawa, Keita; Mcgahan, M.*; Meguro, Yoshihiro; Kinoshita, Hajime*

no journal, , 

Oral presentation

Development of solidification techniques with minimised water content for secondary radioactive aqueous wastes in Fukushima, 6; Incorporation of simulated secondary aqueous wastes in CAC and CAP cements

Garc$'i$a-Lodeiro, I.*; Lebon, R.*; Mahoney, D.*; Zhang, B.*; Irisawa, Keita; Osugi, Takeshi; Nakazawa, Osamu; Kinoshita, Hajime*

no journal, , 

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