Quantification of changes in physical and chemical characteristics of concrete support in Horonobe Underground Research Laboratory, 1; Overview and initial condition of test specimens

Mochizuki, Akihito  ; Matsui, Hiroya ; Ozaki, Yusuke  ; Motoshima, Takayuki*; Jo, Mayumi*; Shibata, Masahito*; Negishi, Kumi*; Sakamoto, Ryo*

In geological disposal of high-level radioactive waste, retrievability of the waste should be ensured until the closure of repository. It is necessary to evaluate the soundness of open pit of the repository so that safe work is possible. This study aims to quantitatively understand changes in the characteristics of concrete support in the actual underground environment. Test specimens of low-alkaline sprayed concrete that were same as those applied in 350 m gallery of the Horonobe Underground Research Laboratory were prepared, placed in the same gallery, and physical and chemical characteristics of the specimens were investigated periodically. This presentation will report on the overview of the study and parts of results to date.