Abstract: In a simple method of filling a wide crack in an exposed surface of an artificial or natural structures, a rigid plate is positioned on the surface, which plate has on the surface of the plate nearer the surface of the structure three enclosures each bounded by an upstanding wall of compressible material. Two of the enclosures (vacuum enclosures) each has an outlet port passing through the plate and one of the enclosures (the injection enclosure) positioned between the vacuum enclosures has two injection nipples passing through the plate. The plate is so positioned on the surface of the structure that the injection enclosure overlies the crack. Air is evacuated through the outlet ports from the vacuum enclosures to cause the rigid plate to be sucked tightly against the surface of the structure and hardenable material in a semi-liquid state is pressure injected through the injection nipples into the injection enclosure until the crack is filled.