Estimation of water content of compacted Kunigel-V1 bentonite using near-infrared spectra

Bentonite has been selected as a candidate buffer material for the deep geological disposal of high-level radioactive waste (HLW). To more effectively control the compaction quality of bentonite blocks, an efficient and accurate method for estimating the water content of compacted bentonite should be developed. A method for estimating the water content of compacted bentonite using near-infrared spectroscopy is proposed in this study. The near-infrared spectra of 60 compacted Kunigel-V1 (KV1) bentonite specimens, with varying water contents and compaction loads, were measured using a near-infrared spectral sensor. Based on the obtained experimental data, a calibration model was constructed through partial least squares (PLS) regression, and its accuracy was evaluated by means of several indicators. The results demonstrated that the calibration model could achieve an estimation accuracy of approximately ± 1.0 %, regardless of the compaction load. These findings confirm the applicability of using near-infrared spectroscopy for estimating the water content of compacted Kunigel-V1 bentonite.