Method for designing bentonite/sand mixture to achieve the target permeability

Bentonite/sand mixture is expected to be an effective component of barriers for radioactive waste disposal facility. Impermeable mixture can be obtained through enrichment of the bentonite content, but it is difficult to estimate a permeability of bentonite/sand mixture before permeability test. At designing of bentonite/sand mixture, we have to decide which sand to be used, and what bentonite content is. But, this means that designing will be a time-consuming task. In this report, we made many kinds of bentonite/sand mixtures using some kinds of sand with different bentonite content, and permeability tests were conducted for these mixtures. After examination of the permeability tests results, the effective void ratio of bentonite/sand mixture which was obtained by compaction test, is an efficient parameter for estimation of the permeability. Last of all, we propose the method of designing bentonite/sand mixture using the effective void ratio.