Abstract: A sealant system for repairing leaking pipes comprised of an elastomeric modified acrylic adhesive, exothermically curable upon activation by a catalyst, and a blowing agent. After mixing the components, the sealant is pumped into a mold cavity located over the leak. The mold is sealed and the reaction of the acrylic proceeds to completion concomitant with a rise in temperature, decomposition of the blowing agent and an increased pressure within the mold. The internal pressure thus generated forces the sealant into the interstices of the pipe. The sealant upon complete curing and solidification is bonded to the surface of the pipe.