PERFORMANCE ASSESSMENT OF CEMENT GROUT BOREHOLE PLUGS IN BASALT

Flow tests have been conducted on expansive cement grout plugs with diameters of 160 mm and 200 mm, and length-to-diameter ratios of one, in boreholes in basalt blocks and in steel pipes. Two types of flow tests have been performed: pseudo-constant head tests and transient pulse tests. Hydration temperatures of cement grout plugs have been monitored in steel pipes with inside diameters ranging from 110 mm to 200 mm. During flow tests, basalt blocks have fractured, presumably due to water injection pressure, cement grout expansion, packer pressure and temperature differences. Falling head tests performed on some block fractures indicate a complex interaction between a cement grout borehole plug and the rock, as determined from the hydraulic conductivities of fractures intersecting plugged boreholes.