Composite slab consisting of in‐situ casted reinforced concrete on profiled sheeting, which is connected to steel beams by shear connectors, is a common structural flooring system in office buildings and car parks. The headed welded studs are inexpensive and rather easy to use in‐situ because they can be welded to the steel beam through the metal sheeting. A permanent link is created between the composite slab and steel beams leading to rather time‐consuming and expensive deconstruction process. Various types of bolted shear connections, recently investigated by various researchers in Europe, Australia, USA, provide a demountable alternative for the flooring system. This paper describes the experimental study using a bolted shear connector consisting of an embedded bolt/coupler and external bolt, originally developed for a prefabricated concrete deck. A full‐scale composite beam was tested under working loads up to 6.25kN/m2 in a 4‐point bending. In addition to bolted shear connectors a timber joist is embedded in the composite slab over the web of the steel beam. After the first life cycle, the timber joist provides the cut edge of the slab. The experiment is used to model behaviour in the first life cycle. The composite slab was then cut, demounted, re‐assembled and tested again in the second life cycle. The load was applied up to 6.25kN/m2 and finally to the failure. Multiple arrangements of shear connectors were investigated to analyse performance of “a modified composite slab”. Experience gained on the experiments of testing the composite beam in the first and the second life cycle is accompanied by FE analysis.@en