Laboratory Researches On Mixing Proportion Of Cement-Bentonite Slurry Cutoff Wall

As a kind of vertical anti-seepage wall material, cement-bentonite slurry is frequently used for the containment of contaminated groundwater and other environmental protection projects (landfills, debris, dams, etc.) abroad. Domestic application of cement-bentonite slurry walls is not extensive. In some practical engineering applications, the hydraulic conductivity of cement-bentonite slurry walls can hardly reach the design requirements. At present, the performance of cement-bentonite slurry wall was rarely studied by domestic scholars. So it is of guiding significance to study the influences of raw materials on the mechanical properties as well as the hydraulic properties of hardened cement-bentonite slurry. In this paper, the mechanical properties and hydraulic properties of cement-bentonite slurry wall were researched from both macro and micro aspects. Some valuable conclusions and results were obtained.Unconfined compressive strength and stress-strain relationship of hardened cement-bentonite slurry with different mixing proportions were tested. The influences of cement and bentonite on the mechanical properties of hardened slurry were analyzed.The hydraulic conductivities of hardened cement-bentonite slurry with different mixing proportions were tested using a permeameter. The impacts of cement and betonite on the hydraulic conductivity of hardened slurry were studied, and some rules of the impacts were summarized.The mechanical properties and hydraulic conductivities of several cement-bentonite mixtures were tested after a curing time of either 28 or 60 days. It was discovered that the time of curing greatly influences the mechanical properties and hydraulic properties of cement-bentonite slurry.Pore structure characteristics(such as porosity, the most probable pore, pore distribution and critical diameter) of hardened cement-bentonite slurry were observed by MIP (mercury intrusion porosimetry). The influences of raw meterials on the pore structure characteristics of hardened cement-bentonite slurry were summarized. Furthermore, the relationship between pore structure characteristics and hydraulicconductivity were analyzed.Finally, the results of this study were analyzed and summarized, and a brief discussion of further research directions was done.