EXPERIMENTAL ASSESSMENT ON BOREHOLE SEALING PERFORMANCE OF SLUDGE-MIXED CEMENT GROUT IN ROCK SALT

Abstract

The objective of this study is to experimentally assess the performance of sludge-mixed cement grouts for sealing boreholes in rock salt. The cement grout is prepared from the commercial grade Portland cement mixed with Bang Khen water treatment sludge, brine and chloride resistant agent. The results are used in the design of borehole seal in rock salt to minimize the brine circulation and potential leakage for the industrial waste repository.  The salt specimens are prepared from the 54 mm diameter cores drilled from the Middle member of the Maha Sarakham formation. The results indicate that the viscosity of grout slurry tends to increase as the sludge-mixed cement (S:C) ratio increases. The compressive strength after 28 day curing times is 9.58±0.52 MPa. The highest compressive strength is from S:C = 5:10. The average tensile strength is 1.99±0.14 MPa. The highest bond strength is 7.49 MPa. When the curing time increases, the intrinsic permeability of cement grouts decreases. Similarities and discrepancies of the grouting performance in terms of mechanical and hydraulic properties are compared.