TotalBoat Thixo Thickened Epoxy Adhesive and TotalBoat Thixo Fast Cure 2:1 Epoxy Adhesive are excellent for filling cracks and small voids in concrete. TotalBoat Thixo Flex Thickened Flexible Epoxy Adhesive may also be suitable for some applications, but because it has a thicker consistency, it may not work into cracks and voids as easily. Be sure to check the maximum gap-filling characteristics of the specific epoxies used.