Concrete-to-concrete connections for modularly reused RC components – an experimental study on separation methods

Abstract

For the reuse of RC structures, structural components like columns or beams are extracted from monolithic buildings to serve as reused modules for newly assembled structures in a sense of construction kits. The scope of this study is an experimental investigation of the newly formed concrete-to-concrete connections between the modules that might transfer compression and shear. The load-bearing capacity of the connections are predominated by the characteristics of the module's edge. For RC, inaccuracies of the surface, damages from separation as well as the stress inhomogeneities due to the cut off reinforcement that ends up bluntly have to be taken into account. The paper presents an experimental campaign on the three named aspects. 16 RC beams with a rectangular cross section are cut by sawing, waterjet cutting or hammering and then tested under centric or eccentric compression. Concrete-to-concrete and concrete-to-steel connections are tested. Process parameters like the cutting speed, cutting depth and post-treatment by grinding are considered and varied. CT and laser scans quantify the micro damage as well as the surfaces’ flatness that arise from the separation. The results show that precise sawing ensures a load-bearing capacity similar to a fully plastic activation of all rebars and concrete areas. On the contrary, rough cuttings significantly diminish ultimate loads. The results are discussed with respect to surface qualities and inevitable micro damages and referenced to newly built RC sections.