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Sawaguchi, Takuma
"Yugai Haikibutsu, Hoshasei Haikibutsu Eno Semento, Konkurito Gijutsu No Tekiyo Kenkyu Iinkai" Hokokusho (CD-ROM), p.165 - 173, 2020/12
no abstracts in English
Fujita, Hideki*; Negishi, Kumi*; Osawa, Tsutomu*; Honda, Akira
Semento, Konkurito Rombunshu, (61), p.262 - 269, 2008/02
The influence of sodium nitrate on dissolution of cement hydrates was investigated by flow through experiment. Dissolution of portlandite was accelerated in NaNO
solution of 1 mol dm
than in ion exchanged water. The acceleration of portlandite dissolution attributed to impact of ionic strength on the activities of aqueous species, because Ca concentration in 1 mol kg
NaNO solution equilibrated with portlandite was estimated to be 1.5 times as high as that in pure water. After flow through experiment, compressive strength fell down and porosity was higher than blank test using pure water. However low permeabilities were contradictory kept during NaNO solution flowing. Dense existence of Na was possible to cause the low permeability during NaNO solution flowing.
Mihara, Morihiro; Torii, Kazuyuki*
Semento, Konkurito Rombunshu, (61), p.331 - 337, 2008/02
In order to evaluate a long-term behavior of hardened high-volume fly ash silica fume cement paste, HFSC, which is considered to be used as filling and structural materials in a repository for the radioactive waste disposal, apparent diffusion coefficients of chloride ion were obtained which might diffused from the surrounded groundwater into the cementitous material. The profiles of chloride concentration in hardened cement paste after the immersion of sodium chloride and calcium chloride solution were measured by electron probe microscopy analysis and apparent diffusion coefficients were calculated fitting these profiles. And, effects of mixture proportion of fly ash content, 40%, 30% and 20%, in HFSC and period of diffusion experiment, 28days and 91days, on the apparent diffusion coefficient were studied from the view point of the pore structure and immobilization ability of chloride ions in HFSC. It was found that the diffusion coefficient of HFSC using 40% of fly ash, HFSC424, was the smallest value in the cement pastes used and the apparent diffusion coefficient degreased as the experimental period. Although HFSC424 had a larger porosity and lower immobilization ability of chloride ion than ordinary Portland cement, it was concluded that the smallest diffusion coefficient was caused by the fine and discontinuous pore structure of HFSC424.
Fujita, Hideki*; Haga, Kazuko*; Shibata, Masahito*; Mihara, Morihiro
Semento, Konkurito Rombunshu, (61), p.65 - 71, 2008/02
The elution behavior of polycarboxylate type superplasticizer from hardened cement pastes were examined by analysis of organic matter in the pore water and curing water. A small quantity of superplasticizer was eluted and a large quantity remained in the solid. Only lower molecular weight matter was detected in the pore water, and decomposition of polymer under high alkalinity environment or selective elution of small molecule were suggested. Though there was the assumption that the effect of primary organic matter in cement like grinding aid was canceled by blank test, the assumption may need to be reconsidered.
Miura, Norihiko*; Konishi, Kazuhiro*; Iriya, Keishiro*; Nakayama, Masashi; Matsui, Hiroya
Semento, Konkurito, (728), p.63 - 67, 2007/10
High level radioactive waste(HLW) repository is to be constructed at depth of over 300m below the surface. Shotcrete and lining will be used for safety under construction and operational period. Concrete is a kind of composite material which is constituted by aggregate, cement and additives. Low alkaline cement has been developed from the viewpoint of long term stability of the barrier systems which would be influenced by high alkaline arising from cement material. Japan Atomic Energy Agency(JAEA) has been developed HFSC(Highly Fly-ash contained Silica-fume Cement) which is one of a low alkaline cement contained silica-fume and fly-ash. JAEA is now implementing the construction of the underground research laboratory(URL) at Horonobe for the purpose of research in deep geological science and repository engineering technology. This report shows the properties of HFSC using as shotcrete.
Maegawa, Toshio*; Umetsu, Tomotake*; Nonaka, Akira*; Yoshimatsu, Kenji*; Sato, Koichi*; Sato, Satoshi; Nishitani, Takeo
Semento, Konkurito, (719), p.26 - 31, 2007/01
no abstracts in English