Development of low alkakinity cement shotcrete for the support of the high-level radioactive waste repositories

Noguchi, Akira; Nakayama, Masashi ; Sato, Haruo

We are developing to apply the Highly fly-ash contained silica-fume cement (HFSC) for the support of the high-level radioactive waste repositories with shot-crete construction technology. We showed that HFSC424, a fifth of binder is changed to silica-fume and two fifth is changed to fry-ash, has as much workability as ordinary portrand cement shotcrete. And reducing water binder ratio to 30%, we can get a mix proportion whose compressive strengh is more than 36 MPa. From June, 2009, we performed spraying test in the 140 m gallery off the west shaft of the Horonobe URL. The support made from this proportion has enough strength and this proportion of the HFSC concrete has good workability. Moreover, the dust on spraing and rebound ratio on spraying is less than ordinary shotcrete. On spraying HFSC shotcrete, the rebound ratio is very low, and less dust than ordinary one. We will construct with HFSC more, and research on the influence to the environment around the support made by the HFSC.