An inflatable grout packer includes a housing having an inner bore. An annular inflatable bladder is received in the inner bore of the housing. The bladder has an inflation cavity defined therein for containing an inflatation fluid. The bladder has first and second axial ends and has radially inner and outer walls. The bladder provides a seal between the housing and an elongated cylindrical member, typically a piling, received through the bladder. First and second end rings are sealingly bonded to the first and second ends of the bladder and also sealingly attach to the housing so that a backup seal is thereby provided against leakage of inflation fluid through the radially outer wall of the bladder. An inflation coupling is attached to the radially outer wall.