Method of 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. For the design of a bentonite/sand mixture, one has to decide which sand to use, and what bentonite content to use. In this report, the authors made many kinds of bentonite/sand mixtures using different 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 the estimation of the permeability. Last of all, the authors propose the method of designing bentonite/sand mixture using the effective void ratio