Control of slaking behavior when flyash cement is injected into slake-prone rock

A large amount of flyash is produced by coal combustion. About 80% of flyash in Japan is now utilized and the remains are dumped at disposal sites; however, the life of these sites is limited. Therefore, in this study, an effort was made to analyze lining materials using flyash cement, in order to more effectively recycle and utilize it. When flyash is added to Portland cement, the same kinds of oxides as those of the cement are added. As an injection component, flyash acts, in part, as a fine aggregate which has a function similar to that of fine debris materials of slake-prone rock and, in part, as a binding component. In order to clarify to what degree the flyash content affects the properties of the lining materials, some different combinations of flyash, Portland cement and water were considered by means of several laboratory experiments, such as a fluidity test, unconfined compressive test, slaking index test and so on. Also, a leaching test was carried out to examine the chemical behavior after the slake-prone rock as an aggregation was mixed with flyash, Portland cement and water.