Soil-water characteristic curves and hydraulic conductivity of nanomaterial-soil-bentonite mixtures

This study evaluates the influence of nanomaterials (nano-copper and nano-alumina) on the suction and hydraulic conductivity of compacted soil-bentonite mixture with different plasticity indexes. The soil suction and hydraulic conductivity of the compacted soil-bentonite mixtures were measured before and after the addition of nanomaterials. Soil-water characteristic curves were then developed for compacted soil samples (with and without nanomaterial) using a pressure membrane apparatus. It was found that saturated water content was lower in the soil samples mixed with nanomaterials. The soil hydraulic conductivity also decreased with increasing nanomaterial content, except for S3 soil sample with nanocopper content. The decrease of hydraulic conductivity was possibly caused by the reduction of the effective porosity due to pore clogging. The results from testing samples after one to four drying times show that the largest rise in soil hydraulic conductivity occurred at first or second drying. Adding nanomaterials can reduce the soil hydraulic conductivity by as much as seven times for soil samples with high clay (bentonite) content.