Ultrasonic Monitoring on Unsaturated Permeation in Sodium Bentonite

Key Points

• To investigate the feasibility of ultrasonic methods for monitoring unsaturated permeation in sodium bentonite.
• Conducted unsaturated permeation tests using compacted sodium bentonite while measuring ultrasonic waves.
• Identified two types of transmission waves corresponding to varying water content levels.
• Analyzed the relationship between the rate of slowness increase and the swelling state of clay minerals.
• Low-frequency mode decays and disappears as water content increases before saturation.
• High-frequency mode appears at around 90% saturation and reaches maximum amplitude and velocity when saturated.
• Findings enhance the understanding of the structure of hydrous clay aggregation systems.