ABSTRACT
Structural precautions: before removal or cutting of any masonry section it must be assessed by a suitably qualified person to check that the damage will not be critical to stability. The removal of single units or small groups from large areas of sound masonry will normally be possible without special precautions but checks should be made if several specimens are to be taken from a limited area. Where single units are required from narrow walls, slender columns, piers etc. the stability must be checked in advance. Checking should precede all removals of sections of bonded masonry unless they are removed from non-critical areas such as from the tops of walls with no vertical load on them or from the bottom of existing window reveals. Particular care should be exercised to ensure that the cutting does not affect composite action in wall beams or interrupt arch lines generated by such action. In cases where the stability of the wall could be impaired some form of temporary load path must be provided before cutting commences. Instrumentation: if the state of strain/stress of the specimen is of interest then strain measuring points should be attached to the specimen and reference measurements should be taken before cutting commences and immediately after cutting. This may enable the stress state in the wall to be assessed and modelled in the laboratory if required. If measurement is delayed after cutting some relaxation will occur giving a greater apparent strain. To obtain full information the gauging must be both vertical and horizontal, on both sides of the wall and replicated to allow averaging.
