PERFORMANCE ASSESSMENT OF CEMENT GROUT BOREHOLE PLUGS IN BASALT

Flow tests have been conducted on expansive cement grout plugs with di ameters 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 test s have been performed: pseudo-constant head tests and transient pulse tests. Hydration temperatures of cement grout plugs have been monitore d in steel pipes with inside diameters ranging from 110 mm to 200 mm. During flow tests, basalt blocks have fractured, presumably due to wat er injection pressure, cement grout expansion, packer pressure and tem perature differences. Falling head tests performed on some block fract ures indicate a complex interaction between a cement grout borehole pl ug and the rock, as determined from the hydraulic conductivities of fr actures intersecting plugged boreholes.