Evaluation of the water retention curves of cement- bentonite cut-off wall materials

Filter Paper, Dynamic Vapour Sorption and Vapour Equilibrium Methods were used to investigate cement-bentonite (CB) materials unsaturated properties. These measurement methods provide an insight into the potential for self-desiccation of CB materials and their ability to uptake and release of moisture. The current paper shows that the type and mineralogy of bentonite play a role in CB mixture performance criteria (i.e., workability/mechanical properties) and water retention behaviour. It was observed that the presence of a polymer in CB materials impaired the slurry performance criteria and water retention properties. The air entry value (AEV) was high in the CB mixture with a higher percentage of silica, and it slightly increased with time due to a pozzolanic reaction. It is believed that the chemical interaction between cement and bentonite is directly responsible for the formation of the CB internal structure matrix that affects its unsaturated behaviour.