[1C05-07] Technology development

11:30 AM - 11:45 AM JST(2:30 AM - 2:45 AM UTC)

[1C07] Study on density measurement methods for bentonite-sand mixtures

*Ayumu Ito¹, Hikaru Oguri¹, Masakazu Chijimatsu¹ (1. Hazama Ando Corporation)

Keywords:

Geological disposal,Bentonite-sand mixture,Site density tests,Backfill material

The impermeable layer of backfill material in geological disposal facilities reduces hydraulic conductivity. Since bentonite-sand mixture density directly affects permeability, appropriate measurement methods are essential for quality control. Conventionally, the paraffin method (JIS A 1225) has been used for density measurement of block-sampled specimens. However, for low-density specimens with 15% bentonite content, paraffin penetration into surface irregularities prevents accurate volume measurement. This study compared the vacuum pack method and 3D scanner laser measurement as alternatives. While the vacuum pack method improves precision through multiple measurements, specimen damage was problematic. The laser measurement method enables non-contact measurement without damage, proving a promising alternative.