Workability study of sand-bentonite-cement mixtures for construction of two-phase cut-off wall

• Main Authors: Cheng, Hongzhan, Li, Wentao, Chen, Renpeng, Yi, Yaolin
• Other Authors: School of Civil and Environmental Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Civil engineering; Bentonite; Cement
• Online Access: https://hdl.handle.net/10356/163334
• Institution: Nanyang Technological University

The workability of fresh materials is critical for sand-bentonite-cement cut-off wall; however, previous studies are limited to the one-phase construction method, not the two-phase. Hence, this study attempts to fill the gap. First, series of flowability and bleeding tests on sand-bentonite mixtures were conducted (1st phase); subsequently, cement slurry was added to mixtures (2nd phase) to investigate its effect on the workability. The results indicated that, for sand-bentonite mixtures with required workability for 1st phase of construction, the addition of cement caused significant increase in flowability and bleeding, i.e. reducing the workability for 2nd phase, especially for sodium bentonite. The reason was revealed as the short-term interactions (mainly cation exchange) between bentonite and cement hydration products, reducing water retention capacity and swelling potential of bentonite.