collar and head joints allow grout to flow well beyond the crack and to make contact with the adjacent bricks the grout hardens and bonds loosened bricks into the wall and restores strength lost when the original bond of mortar to brick was lost due to cracking blocks 110 form a header course the void system is occasionally blocked by a full collar joint 106 mortar 104 may be squeezed out of the bed joint the present method is suitable for repairing various types of cracks referring once again to fig2 cracks 54 and 66 can be repaired by the present crack injection process in addition to repair of the crack itself framings supported on the adjacent wall around the corner should be investigated for loss of or reduction of support and appropriate repairs made preferably the shear connection of the diaphragms to the wall will also be made crack 56 can also be repaired by the present injection process a steel lintel at the top of the opening will prevent injection into the full wall thickness adjacent to the beam if injection is done from only one side of the wall cracks 58 55 and 65 will generally be closed by gravity and cannot receive injected grout grout can be used to fill the collar joints adjacent to the crack and bond adjacent loosened bricks crack 67 generally cannot be repaired by injection arches generally are built with special effort to completely fill collar and head joints voids are small and not interconnected so that the injection process is not generally effective an arch with loose bricks or with a part of the arch badly displaced downward should ordinarily be rebuilt referring still to fig2 cracks 69 do not have the.